LPP用のCO2レーザーシステムの開発、更に電子ビームをプレパルスとして用いた際に発生するLPP光の量の計測を実施することで、将来の高効率LPP生成に向けた、基礎的なデータ取得を目的として研究を遂行した。 フォトカソード励起用レーザーの安定化とマルチパルス化を行い、その安定発生を実現した。またCO2レーザーについては、レーザーエンハンスキャビティの設計製作を行い、高Finesseシステムの構築に成功した。最終的には、高出力のCO2レーザー(パルス幅、400ns)を利用しての、LPP生成実験を実施し、電子線のマルチパルス(10バンチ)プレ照射法により、出力を約1.5倍に高めることに成功した

フェムト秒パルスレーザー3倍高調波出力の高強度化(1.0mJから2.7mJへ)及び高安定化(pointing and energy stability <1.0%)を進め、光カソードからの90フェムト秒電子単バンチ及び4ミクロバンチビーム生成・加速(8MeV)後、遷移放射、スミスパーセル放射によるブロードバンド及び準単色化THz(0.3～10THz)特性測定を行った。2から4ミクロバンチ生成によるTHz超放射確認実験は、30cm-5周期小型ウィグラー磁石を使って行った。ウィグラー磁石Gap調整によりFEL共鳴放射条件を満足させた結果、Sub-THz超放射測定に成功した。THz応用実験も行った

本研究においては、我々が持つ、高品質電子ビーム発生装置、レーザーフォトカソードRFガンを用いて、総合的な研究を進めてきた。具体的には、電子ビームの空間―時間変換を可能とする、RFディフレクターキャビティーの実現と、そこへフィードを行う、マイクロ構造を持つ電子ビームの生成研究を行った。具体的には、ナノメートル加工技術を駆使し、簡易的に作成したマイクロスリットを用い、電子ビームの切り出し実験にも成功した。更にRFディフレクターを用いて空間―時間の変換についても成功し、マイクロビーム制御技術を確立、コヒーレントコンプトンに必要な基礎技術を確立することができた

4枚のミラーを立体的に配置する全く新しい着想の「3D・4枚ミラー・リング型レーザー光蓄積空洞」を設計、製作し、その性能を確認した。このレーザー光蓄積空洞はレーザー・コンプトン散乱にもとづいた高強度・高エネルギー光子源に用いるためのものである。開発されたレーザー光蓄積空洞ではフィネス約4000、蓄積パワー2.6 kW, レーザー光・電子衝突点での垂直スポットサイズ13±1 ミクロン(RMS)が実現された。このレーザー光蓄積空洞を使ってビーム衝突一回あたり124±1 個の光子の生成が確認された。これは毎秒2.7x108 個の光子生成に相当する。生成された光子の平均エネルギーは24 MeV である

放射線治療の新しい方法として、微小平板ビーム放射線療法(MRT)が提案されている。本研究では、SPring-8放射光を用いたMRT動物実験の照射条件、動物実験による作用機構、高エネルギーX線の利用可能性、治療法としての最適化、の検討を行い、照射の際にアライメントの精密化が必須であること、作用機構としては照射後に腫瘍内に低酸素細胞の増加を確認したこと、また適正なビーム幅があること、およびX線のエネルギーとして100-250 keVが適正と考えられることなどを明らかにした

架橋体を含むパーフルオロ系高分子に対して、各種イオンビームにより、マイクロ～ナノサイズで制御された精密微細加工を行った。その後、グラフト重合により機能化し銀イオンを担持した試料を調製した。量子ビームにより固相中直接還元を行い、SEM-EDXやXPSで構造解析を行った結果、純銀ナノ粒子を確認できた。また、加工体を観察した結果、60. m角のアレイ状の電極を作製ができた。また、直接パターニングにより幅800nmの金属還元微細加工体の作製に成功した

レーザーフォトカソードRFガンから得られる電子ビームの大出力化のための、レーザーのマルチパルス増幅を実施した。具体的にはNd:YLFレーザーの基本波である1047nmの119MHzのIR光を特別に設計したモジュレータにより自在に切り出す事に成功した。これにより、今回、100パルスの大強度IRレーザーを後置の増幅器により生成し、その後非線形結晶により2倍高調波及び4倍高調波であるUV光へ変換することに成功した。また、衝突用のレーザー光を増幅するためにパルスレーザー蓄積装置を実現し、マルチパルスX線の発生に成功した。本研究において予備的ではあるが、生体のX線像を取得した

高反射率ミラー光共振器にパルスレーザー蓄積(1000倍の蓄積増幅)と同時に数ミクロンレーザーワイヤーウェスト(30um,5um)またはサブミクロンレーザー干渉縞(干渉縞ピッチ500nm)の安定生成、およびレーザーと高エネルギー電子ビームの衝突によって、数ミクロンからサブミクロンサイズの高エネルギー電子ビームサイズ測定が可能であることを示した。実用化の為に小型光共振器およびパルスレーザー発振装置製作を継続している

1)フッ素系高分子、例えばFEPとETFEのブレンド膜を合成し、融点付近で窒素雰囲気中電子線照射して、架橋我々は放射線グラフト法を用い、架橋PTFE(RX-PTFE)を基材とした固体高分子形燃料電池(PEFC)用の電解質膜の開発を行ってきた。
今年度の研究は、イオン交換容量が1.7から2.3meq/gまでのスチレン及びスチレン/DVBをグラフトした電解質膜を利用してMEAを作成した。Nafion112膜を参考膜として利用し、同条件下でMEAを作成し、発電実験を行った。その結果、合成した電解質膜の開路電圧(OCV)はNafion112膜より0.1V程度低くなった。その原因は合成した電解質膜の厚さがNafion112膜の1/3程度と薄かったことにあると考えている。室温及び60℃で合成した電解質膜の発電効率はNafion112膜よりやや低いものの、80℃の低加湿条件では、合成した電解質膜の発電効率はNafion112膜より優れていた。スチレン/DVBをグラフトした電解質膜とスチレンをグラフトした電解質膜と比較してみたところ、高いOCVが得られ、電極との界面抵抗も低く明らかな優位性を示した。
2)一方、高温での放射線架橋法を応用して、芳香族高分子架橋膜の開発に適用する研究を行った。
PES膜をガラス転移温度付近(230℃)で窒素雰囲気中で電子線照射して、架橋PES膜を作成することに成功した。ゲル分率は作成した膜を溶剤に浸漬し測定した。室温照射では電子線を照射したすべて膜においてゲルが生成しなかったが、高温照射したPESではゲル分率が吸収線量の増加に伴い増加した。このゲルの生成は、このように特殊な温度条件でPES膜を放射線照射すると架橋構造を導入できることを初めて明らかにした。得られた結果から、切断と架橋のG値も求めた。また、熱分析の結果からも、230℃での照射により架橋できることを示した。
この結果を利用し、PESとフッレンド膜を作成することにも成功した。ゲル分量と熱分析の結果から、得られたPESブレンド膜の架橋構造についても明らかにした。

平成18年度は特に、全固体Nd : YLFレーザーの一層の高輝度化研究と軟X線発生システムの高度化による輝度増強とノイズ除去について集中的に研究を進めてきた。具体的には以下のような研究の発展を見た。我々はNd : YLFレーザーからのIR光を取り出した後更にマルチパスアンプを組み、レーザーパワーの増強を目指した。昨年度のIRレーザーのパワーは最大でも20mJ程度であったがなお一層の高輝度化を目指して、後置のNd : YLFレーザーロッドとフラッシュランプを用いた増幅器を複数回通すことで輝度増強を行った。結果、3パスアンプシステムを構築し、30mJを超えるIRパルスを安定的に得ることに成功した。一方軟X線発生システムの高度化のために、今年度は新たに次のコンセプトを実現するための新しい衝突チェンバーを導入した。すなわち、昨年度までは電子線を衝突点で収束することに伴い、衝突後にビームが発散し、ビームダクト等との相互作用により大きな制動X線によるノイズの影響を大きく受けていた、また衝突用レーザー光もチェンバー内での散乱によりX線計測システムに大きなバックグランドを与えていた、そこで今年度は、電子ビームおよびレーザー光の通過する空間を自由空間とし、電子ビームのハロー等に伴うX線発生を極限まで低減化し、またレーザーについても散乱による計測システムに対するノイズを非常に小さくすることに成功した。また更に、衝突角の自由度、衝突点のスキャンなど、軟X線顕微鏡開発の基礎データを極めて精度よく取得することに成功した

フォトニック結晶は,これと相互作用させる電磁波の波長程度の格子定数を持つ人工結晶である.電磁波としてレーザーを用いる場合,格子定数は1μm以下になる.この,フォトニック結晶と電子ビームとが関連するふたつの実験を行った.第一の実験はフォトニック結晶からの放射光発生である.回折格子表面に平行に電子ビームを走らせたときに,格子面と垂直方向に発生する放射光はスミスパーセル光として知られている.回折格子の代わりに2次元フォトニック結晶をもちいると,電子ビームの分散とブリリアン図との交点に対応する(ω,k)を持つ光の観測が期待される.阪大産研のエネルギー35MeVバンチ電荷1nCバンチ長5psのレーザーフォトカソードrf電子銃ライナックと,広大製Siフォトニック結晶による実験では,予期されない(ω,k)成分を持つ放射光が豊富に観測された.スミスパーセル光を観測するためには電子ビームを格子定数以内の距離(すなわち1μm以下)で結晶表面に平行に走行させる必要がある.しかしビーム自体のサイズが数mmであったため,この条件を満たすことは不可能であった.このため,スミスパーセル効果以外の機構で発生した光が雑音として観測されたものと思われる.第二はフォトニック結晶ファイバによる電子加速である.レーザー加速の問題点のひとつは,レーザーの焦点付近でしか大きな加速勾配が得られないことである.小径で長距離レーザーを伝播させる技術が必要である.通常の光ファイバは周囲より誘電率の大きいコアに光を閉じ込める.この構造ではビームを走行させる空間がない.しかしフォトニック結晶のバンドギャップに対応する光(ω,k)は結晶内部に入り込めないという性質を利用すれば,コアを空間としてそこにレーザーを閉じ込めることが出来る.このときレーザーは誘電体との相互作用により縦電場を作るので,この電場で電子ビームを加速することを試みた.ファイバはCrystal Fibre社800nm仕様の,直径6μmのコアを三角格子をなす1μmの孔がとりまいた形状のものを使用した.12mm長のファイバのレーザー透過率は8%強で,ここにパワー700GW,パルス幅50fs,直径30μmのレーザーを入射したところ,450keVまでの電子を観測した.またこれとは別に再現性は悪いが2MeV程度の電子群も観測された.実験で得られたレーザー透過率はカタログ値の1/10程度なので,レーザーとファイバーのカプリングに改善の余地がある

成果の概要電子・レーザー間での逆コンプトン散乱を現実のものとするために、電子ビームの徹底した高品質化を目ざし、超低エミッタンス電子ビームを発生できる、レーザーフォトカソードRFガンシステムによる電子ビーム発生を行い、ピコ秒単パルス電子ビーム発生に成功した。また衝突用のレーザーシステムの安定化を実施し、基準信号に対する時間ジッターを0.26ピコ秒以下と、逆コンプトン過程を高度化するために必要な基礎開発に成功した。さらに、得られた電子ビームのエネルギー、エミッタンス等の重要な物理データを取得し、従来の電子ビーム装置より格段に高品質なビーム(具体的には、規格化エミッタンスで数mm・mradという、従来の熱電子銃で得られる値より一桁以上良好な値。)が得られることを確認した。また電子ビームのパルス長計測についても、ビームスペクトラム法という非破壊方式で、しかもオンタイムに計測が可能なシステムの開発も行った。その結果、5ピコ秒以上の電子ビームに対しては、高精度にパルス長を計測できるシステム開発に成功した。さらに、逆コンプトン散乱過程のシミュレーションを実施し、逆コンプトン過程による、X線発生の最適化を行った。これらデータを用いて、時間及び空間の同期を高精度に行うことのできる新しい発想の衝突用チェンバー(真空容器)を設計・製作し、実際のビームラインに設置した。また、この後、衝突用のレーザーのパワー増幅を含めた、全体システムの高度化を実施した。その結果、平成15年1月に真空中での軟X線(エネルギー300eV(エネルギー可変)、パルスあたりの高指数6000個、エネルギー幅1%)発生に生成に成功した。ここで得られた軟X線は将来、生体観測用の軟X線顕微鏡への応用が可能であり、波及効果は極めて大きい

BNLにおける研究高いルミノシティーのレーザー-電子ビーム衝突を達成するため、強収束・正面衝突型コンプトンチェンバー(CC)を設計・製作した。11年10月には、BNLにおいて、60MeV電子ビームとギガワット(GW)CO_2レーザーを用いて実験が行なわれ、X線のピーク値において世界最高ピーク強度7×10^<18>(光子/秒)を達成した。また、衝突距離を拡大するため、プラズマチャネル中にレーザーをとじこめ、電子線とのコンプトン散乱を実現する。2cm長、半径300μmのプラズマセルを製作し,セル中で低密度プラズマ(10^<17>/cm^3)生成にはじめて成功した。近い将来、これをBNLで製作したプラズマチェンバーに組み込み、「プラズマ中でのコンプトン散乱」についての実験を実施する予定である。KEKにおける研究KEKにおいては、コンプトン散乱、電子-陽電子対生成を通じて、偏極陽電子生成のための系統的な研究を進めた。実験では、532nmレーザーとKEK-ATFからの1.28GeV電子ビームのコンプトン後方散乱により、パルスあたり、2×10^5個のガンマ線を生成した。JLCでは、パルスあたり10^<10>という強い電子・陽電子ビームと、複雑なバンチ構造(2.8ns間隔で95個というパルス群を150Hzで生成)が要求される。我々は、エネルギー5.8GeV、バンチあたりの強度5×10^<10>の電子ビームとCO_2レーザー50台を用いて概念設計を行い、バンチあたり3.6×10^<10>の陽電子が発生することを確認した

本研究を進めるにあたり、基礎的開発段階とその実用化による最終目的の達成段階の2段階に分けて系統的な研究を進めることにした。低速偏極陽電子ビーム生成には、多種多様な実験技術が関係しており、それらの技術要素を一つづつ理解しその性能を最大限に発揮させることは、着実に目標に接近できる最良の方法と考えたからである。基礎的開発段階の技術要素としては、次のような課題がある。1)電磁場中における偏極陽電子のスピン運動の理解。2)高強度偏極陽電子ビームの生成。3)ビームバンチングシステムの実用化。4)ウイーンフィルターの開発。5)偏極度測定法の確立。6)陽電子プロファイル測定法の確立。7)多重ガンマ線測定装置の建設。8)陽電子発生メカニズムの解明。これらの課題が解決すれば、その総合としての偏極マイクロビームを実現することは射程距離内にあると思われる。本研究では、全力挙げてこれら個々のの課題に取り組み最良の結果を得るべく努力した結果り、上記のすべての課題について、期待どうりの成果を得ることができた。とくに、2),3),8)については、初期の予想を上回る成果を得ることができ、研究は最終目標にむけて大きく加速ことになった

東大原子力工学研究施設35MeVライナックで、自由電子レーザー特性に大きな影響を与える電子ビームパラメータの測定を行った。パルス平均のエネルギ分散は約2%であったが、パルス内で時間とともにピーク強度が減少し低エネルギ側にサブピークが成長するなどのスペクトルゆらぎが見られた。ビームダイナミクスを評価するコードを開発して検討した結果、この原因はクライストロン出力の約1%の出力変動にあることが知られた。周期数10,周期4cmのウィグラ磁石をライナックに設置し、電子ビームから生ずる自由電子レーザー自発放射光のスペクトル測定及び写真撮影を行った。中心が黄で外側にゆくにつれ波長が長くなり赤へ変化するリング状の放射スペクトルが観測された。さらに外側では2倍高調波である青・緑のリングが見られた。スペクトル測定結果は中心波長490nm,半値幅112nmであった。これらの結果を自発放射光発生メカニズムに基づく一様拡がりに加えてエネルギ分散・エミッタンス・磁場精度等に起因する非一様拡がりを考慮して評価し、理論値と良く一致すること及び自由電子レーザー性能の評価において考慮する必要があることを確認した。粒子シミュレーションに基づく自由電子レーザー解析コードを開発した。これを用いて実際のビームパラメータをとり込んだ発振計算を行い、ビームパラメータの増幅率に与える効果及び立ち上がりから飽和に至る過渡過程の特性を検討した。エネルギ分散の効果は飽和までの時間の増加となってあらわれ、パルス内でレーザー発振させるためには増幅率等の設定にこの過渡過程を考慮する必要のあることが知られた。以上のとおり、各種の実験・測定及び開発した解析コードによる検討を行い、自由電子レーザーの原子力分野への応用に係る基礎特性とその可能性を明らかにした

本研究課題では,液晶の分子構造,相状態,分子配向や高分子の架橋密度など種々の項目を検討し最適化するとともに,電子線架橋,光架橋,精密重合などの手法を駆使し様々な基材フィルムとの強固な異種界面接合を形成することにより,高性能光運動材料の構築を目的としている。本年度は,高性能高分子光運動材料の構築において必要不可欠である駆動原理探求を目的として,種々の架橋液晶高分子を合成するとともに,分光法および力学物性評価法を用いて,分子レベルから巨視的レベルまでメカニズムを検討した。架橋液晶高分子におけるアゾベンゼンの影響を結合位置および濃度について詳細に調べたところ,架橋部位にアゾベンゼンを20%程度含む場合に最も高い発生応力を得られることが明らかとなった。光運動挙動は,分子構造,分子の初期配向,異性化挙動,温度,光強度,光照射時間などに大きく依存し,アゾベンゼンの光異性化を分子配向変化へ増幅するプロセスが極めて重要であることがわかった。材料形状の変化についても検討を行った。より自由度の高い光運動材料を目指して繊維状の架橋液晶高分子を作製し光照射を行ったところ,照射方向に応じて三次元的な光運動を誘起できた。一方,アゾベンゼン液晶高分子とPVAを交互にスピン塗布した膜を作製したところ,従来と異なる光屈伸挙動を観察できた。新たな基材の開発および異種界面接合の形成についても検討を進めた。塩化コバルトを有機アルミニウムで活性化した触媒系を用いて少量のホスフィン共存下ブタジエンの重合を行うことにより,結晶性のシンジオタクチック1,2-連鎖と非晶性のシス1,4-連鎖からなるマルチブロック共重合体の合成に成功した

本稿では、早稲田大学を中心としたグループでこれまで行ってきた高エネルギー重粒子線による高分子材料への照射効果とその応用に関して記述する。重粒子線照射による放射線化学反応の微小空間における局所性に関して研究を行ってきた。得られた知見を元に、微小空間での重粒子線のエネルギー付与量を制御し、空間的に制御された分布を持ったラジカルを誘起し、グラフト反応させることを通じ、空間制御型の機能性材料(PEFC:Polymer Electrolyte Fuel Cell)の創製を行ってきた。(著者抄録)

© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. The interactions of short pulse lasers with matter are interesting subjects not only in applications such as surface fabrication but also in physical phenomena for study. Optical short pulse lasers have abilities to occur the ablation phenomena accompanying the creation of high temperature, high pressure, and excited states of electrons. The picosecond soft x-ray laser (SXRL) pulse also has ability to occur the ablation. The SXRL having the wavelength of 13.9 nm and duration of 7 ps is one of attractive x-ray source for ablation study, because the ablation threshold obtained with the focused SXRL pulse is much smaller than those obtained with other lasers having longer durations and/or longer wavelengths. The low ablation threshold of a material for the SXRL beam has a possibility of efficient nanometer scale surface machining by an ablation. The ablation study will lead to the physical research and the direct surface machining. In addition, the wavelength of the SXRL is very close to the wavelength of the extreme ultraviolet (EUV) lithography system (λ = 13.5 nm). In the presentation, we report on development of the soft x-ray laser irradiation system. The irradiation system has an intensity monitor based on the Mo/Si multilayer beam splitter. This intensity monitor provides the irradiation energy onto sample surface. The SXRL has an ability to confirm the ablation threshold and to examine the damage property of EUV optical elements, which have the same specifications of those in the EUV lithography. And more, it is possible to evaluate the doses for sensitivity of resists.

We demonstrate the creation of a vector beam by tailoring geometric phase of left- and right- circularly polarized beams. Such a vector beam with a uniform phase has not been demonstrated before because a vortex phase remains in the beam. We focus on vortex phase cancellation to generate vector beams in terahertz regions, and measure the geometric phase of the beam and its spatial distribution of polarization. We conduct proof-of-principle experiments for producing a vector beam with radial polarization and uniform phase at 0.36 THz. We determine the vortex phase of the vector beam to be below 4%, thus highlighting the extendibility and availability of the proposed concept to the super broadband spectral region from ultraviolet to terahertz. The extended range of our proposed techniques could lead to breakthroughs in the fields of microscopy, chiral nano-materials, and quantum information science.

© 2018 Author(s). A free-electron laser (FEL) is a robust tool for studying the interaction of intense X-rays with matter. In this study, we investigate the damage threshold and morphology of fused silica irradiated by extreme ultraviolet femtosecond pulses of a FEL. The experimental results indicate the superiority of the FEL processing. The FEL-damage threshold of fused silica at a wavelength of 13.5 nm is 0.17 J/cm 2 , which is 20 times lower than that of a near infrared (NIR) femtosecond laser. The relationship between the crater depth and laser fluence reveals that the effective absorption length is α eff-1 = 58 nm. The damage threshold and the absorption length are the key values for smooth crater formation. In addition, the formation of rim structures and microcracks, which are usually the critical issues in NIR laser processing, cannot be found in the interaction region. The hole diameter is maintained below the beam size at the exit.

Crab crossing of electron beam and laser pulse enables head-on collision in laser- Compton scattering. We will report prospects of crab crossing laser-Compton scattering and a suitable laser system based on a thin-disk regenerative amplifier.

A power enhancement optical cavity is a compelling means of realizing a<br />
pulsed laser with a high peak power and a high repetition frequency, which is<br />
not feasible by using a simple amplifier scheme. However, a precise feedback<br />
system is necessary for maintaining the narrow resonance condition of the<br />
optical cavity, and has become a major technical issue in developing such<br />
cavities. We developed a new approach that does not require any active feedback<br />
system, by placing the cavity in the outer loop of a laser amplifier. We report<br />
on the first demonstration of a mode-locked pulse oscillation using the new<br />
system.

© 2016 Author(s). We demonstrated the operation of a high finesse optical cavity without utilizing an active feedback system to stabilize the resonance. The effective finesse, which is a finesse including the overall system performance, of the cavity was measured to be 394 000 ± 10 000, and the laser power stored in the cavity was 2.52 ± 0.13 kW, which is approximately 187 000 times greater than the incident power to the cavity. The stored power was stabilized with a fluctuation of 1.7%, and we confirmed continuous cavity operation for more than two hours. This result has the potential to trigger an innovative evolution for applications that use optical resonant cavities such as compact photon sources with laser-Compton scattering or cavity enhanced absorption spectroscopy.

© OSA 2016. Picosecond, high average power laser is critical in the HVM EUV source technology. 100kHz, mJ, laser is realized by thin disc laser architecture for LPP, and &gt; MHz laser is discussed for 10kW level EUV FEL.

Copyright © 2016 CC-BY-3.0 and by the respective authors. We have been studying an S-band Cs-Te photo-cathode rf gun at Waseda University. The high quality electron beam produced by the rf gun is used to generate a high-power coherent terahertz pulse via Cherenkov radiation. This terahertz pulse can be applied to imaging and material analysis. As a preliminary step towards material analysis, we conducted experiments on terahertz time domain spectroscopy by EO sampling method to reveal major parameters of the terahertz pulse such as the pulse form and the spectrum. EO sampling method has high frequency response and suitable for high peak power terahertz pulses. In terahertz time domain spectroscopy, the duration of the probe light needs to be much faster than that of the terahertz pulse. Therefore, we developed a mode locked Yb fiber laser based on nonlinear polarization rotation as a reliable and cost-effective ultra-fast probe light source. The laser generates 3.59 ps chirped pulses which are compressed to 209 fs with a grating pair. In this conference, we will report the performance of the Yb fiber laser and results of EO sampling experiments.

Copyright © 2016 CC-BY-3.0 and by the respective authors. We have been developing a compact accelerator based on a laser photocathode rf electron gun at Waseda University. Low emittance and short bunched electron beam can be generated from the gun. Also, the rf transverse deflecting cavity was developed for the bunch length measurement. We performed an experiment for generating a coherent Cherenkov radiation using bunch tilting. The rf transverse deflector can give a tilt for the electron bunch, and the tilt angle was set to the Cherenkov radiating angle which determined by the target refractive index. We successfully demonstrated a coherent Cherenkov radiation and the characterization of the radiation. The principle of coherent Cherenkov radiation generation, the experimental results and future prospective will be presented at the conference.

Copyright © 2016 CC-BY-3.0 and by the respective authors. We have been developing a compact X-ray source based on Laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. Our aim is to take a phase contrast image with Talbot interferometer within a few minutes at present. Owing to this, we need the flux of X-ray is 1.7×107 photons/pulse with 10% bandwidth. In the accelerator, an electron beam with the energy of 18-24MeV is generated by an S-band normal conducting accelerator. An electron beam collided with a laser pulse stacked in a 4-mirror planar optical cavity and then 6-10 keV X-rays are generated by LCS. Recently, X-ray imaging experiments such as refraction contrast imaging and phase contrast imaging with Talbot interferometer has been conducted. The flux of 9keV X-rays was 3×106 photons/sec with total band. Further improvements to realize the design X-ray flux are continued.

Copyright © 2016 CC-BY-3.0 and by the respective authors. In laser produced plasma (LPP) EUV source, high intensity pulse CO2 laser is essential for plasma generation. To achieve high conversion efficiency and stable EUV power, we would like to measure a laser profile in the interaction point. However, there is no way to measure directly the laser profile of such a high intensity laser at the focus point. Therefore, we have been developing the direct high power laser diagnostic technique based on laser Compton scattering (LCS). LCS signal by using focused electron beam shows 1D laser profile. 2D laser profile can be reconstructed by one-dimensional laser profiles from various angles using computer tomography (CT). This method is suitable for high intensity laser, but very small spot size of electron beam is required. To obtain small spot size, we used S-band Cs-Te photocathode RF-Gun and specially designed solenoid lens at Waseda University. We already succeeded in observing minimum beam size of about 20μm rms and this is adequate to scan the CO2 laser. In this conference, we will report the result of the laser Compton scattering with pulse CO2 laser, the preparatory experiment in measuring a metal wire cross section and the present progresses.

Based on our previously developed scheme to stabilize nonplanar optical resonant cavities utilizing polarization caused by a geometric phase in electromagnetic waves traveling along a twisted path, we report an application of the technique for a cavity installed in the Accelerator Test Facility, a 1.3-GeV electron beam accelerator at KEK, in which photons are generated by laser-Compton scattering. We successfully achieved a power enhancement of 1200 with 1.4% fluctuation, which means that the optical path length of the cavity has been controlled with a precision of 14 pm under an accelerator environment. In addition, polarization switching utilizing a geometric phase of the nonplanar cavity was demonstrated. (C) 2015 AIP Publishing LLC.

We have been developing a pulsed-laser optical enhancement cavity for laser-Compton scattering (LCS). LCS can produce high brightness X-ray through the collision between relativistic electrons generated from the accelerator and high power laser photons with a compact facility. In order to increase the number of collisions/sec, high repetition rate accelerator and laser are required. For the laser system, an optical enhancement cavity is the most powerful tool for LCS, thus we have been developing the cavity for storing 1 micron laser pulse. On the other hand, the resulting X-ray energy can be changed by the collision laser wavelength. If we have another optical cavity with different wavelength, the multicolor, quasi-monochromatic, high brightness and compact X-ray source can be realized. Therefore, we started to develop an optical cavity at 10 micron wavelength with CO2 laser. At this wavelength region, the absorption loss is dominant compared with scattering loss. Thus we carefully chose the optical mirrors for enhancement cavity. We demonstrated a more than 200 enhancement factor with 795 finesse optical cavity at 10 micron CO2 laser. Moreover, 2.3 kW storage in the optical cavity was successfully demonstrated. The design of optical cavity, first experimental results and future prospects will be presented at the conference.

We have been studying a high finesse enhancement cavity for photon target of Laser Compton Scattering X-ray generation. It is very important to develop an extremely stable external optical cavity for laser Compton scattering. At the same time, a stable seed laser oscillator for an incident laser of an optical cavity is also very important tissue. Thus, we have been developing a stabil mode-locked Yb-doped fiber laser based on Non-Linear Polarization Rotation. We have generated laser pulses which have 102.9mW average power at repetition rate of 119MHz. Furthermore, we started accumulating lasers in the optical cavity, and we have already confirmed that our oscillator is able to accumulate in the cavity.

Copyright © 2015 CC-BY-3.0 and by the respective authors. We have been developing a compact X-ray source via laser-Compton scattering (LCS) at KEK-LUCX (Laser Undulator Compact X-ray source) facility. The LUCX system is based on S-band normal conducting linac with an energy of 30 MeV and optical enhancement cavity for photon target. As a photon target, we invented a burst mode laser pulse storage technique for a normal conducting linac, which enables to store the high power laser pulses at the timing of electron bunches. The peak storage power exceeds to more than 250 kW with 357 MHz repetition. Electron linac is under operation with multi-bunch mode, 1000 bunches/train with 600 pC charge in each bunches. We have succeeded to produce 1000 pulse/train LCS X-ray train. Combining high repetition rate electron linac and burst mode optical enhancement cavity, more than 109 ph./sec/10% b.w. flux would be possible. In this conference, the introduction of our test facility LUCX, recent experimental results, and future prospective including normal conducting LCS X-ray source will be presented.

Copyright © 2015 CC-BY-3.0 and by the respective authors. We have been studying a compact electron accelerator based on an S-band Cs-Te photo-cathode rf gun at Waseda University. The system is using S-band rf of 2856MHz. When a repetition of the electron bunch is integral multiple of rf, it enables a lot of electron bunch acceleration for the rf gun. The repetition of the electron bunch generated by a photo-cathode rf gun depends on the oscillating frequency of the pulsed mode-locked laser. We have been developing a mode-locked Yb-doped fiber laser based on Non-Linear Polarization Rotation (NLPR). However, its repetition is limited by the fiber length to produce NLPR. So we have started to develop the external optical cavity which is multiplier of a pulsed laser repetition. It would enable the rf gun to generate high-dose electron beam in a very short time. In this conference, we will report design of the external optical cavity to multiply the pulsed laser repetition, the experimental results of the frequency multiplying of a mode-locked Yb-doped fiber laser, and the future prospects.

Copyright © 2015 CC-BY-3.0 and by the respective authors. We have been developing a compact X-ray source based on inverse Compton scattering (ICS) between an electron beam and a laser pulse stacked in an optical cavity at Laser Undulator Compact X-ray (LUCX) accelerator in KEK. The accelerator consists of a 3.6-cell photo-cathode rf-gun, a 12-cell standing wave accelerating structure and a 4-mirror planar optical cavity. Our aim is to obtain a clear X-ray image in a shorter period of times and the target flux of X-ray is 1.7×107photons/pulse with 10% bandwidth at present. To achieve this target, it is necessary to increase the intensity of an electron beam to 500 nC/pulse with 1000 bunches at 30 MeV. Presently, we have achieved the generation of 24 MeV beam with total charge of 600 nC in 1000 bunches with the bunch-by-bunch energy difference is within 1.3% peak to peak. The beam-loading has been compensated by injecting the beam before rf power has been filled (ΔT method) and by modulating the amplitude of the rf pulse. We report the results of the multi-bunch beam generation and acceleration in the LUCX accelerator.

Copyright © 2015 CC-BY-3.0 and by the respective authors. We have been studying the pulse radiolysis using photo-cathode rf gun at Waseda Univ. Pulse radiolysis is one of the powerful methods to trace early chemical reactions by ionizing radiation. In pulse radiolysis, the probe light absorption, which produced by active species formed by electron beam of rf gun, is measured at each wavelength and made possible to trace reactions. Therefore, we have used the super continuum (SC) light for the probe light. The SC light has a broad spectrum and is generated by nonlinear optical effect caused by injecting picosecond laser to photonic crystal fiber (PCF). However, the resulting SC light was unstable because its peak intensity was not enough. We need to use a femtosecond pulsed laser which is expected to be stronger peak intensity than a picosecond laser. We have developed a mode-locked Yb-doped fiber laser based on Non-Linear Polarization Rotation as a femtosecond pulsed laser and the chirped pulse amplification system which will be able to amplify the femtosecond pulse. In this conference, we will report the performance of the SC light using this fiber laser system, recent results of pulse radiolysis experiments and the future plans.

Copyright © 2015 CC-BY-3.0 and by the respective authors. At Waseda University, we have been studying high quality electron beam with an rf electron gun. In recent accelerator study and application researches, high quality electron beam are strongly required. Photocathode is a key component to generate higher quality electron beam, thus we started to develop a Cs-Te photocathode as an electron source since 2007. Cs-Te photocathode shows high quantum efficiency (Q.E.) (∼10 %) and has long life time (∼several months). From 2013, we built a photocathode evaporation chamber and started photocathode study. In this study, our purpose is to clarify their property and to establish an ideal evaporation recipe. We succeeded in producing high quality Cs-Te photocathode, and electron beam generated by our Cs-Te photocathode shows high charge (4.6 nC/bunch) and high Q.E. (1.74 %) in our rf electron gun. Furthermore, we found a Q.E recovery after Cs deposition process and it causes higher Q.E. than usual due to, we believe, Cs deposition quantity or Cs deposition speed. Thus we are now surveying the optimum Cs evaporation parameters. In this conference, we will report a detail of our photocathode development system, the latest progress of optimization study of Cs-Te photocathode and future plans.

The coherent radiation spectrum extends into the far-infrared/THz region when the electron bunch is shorter than 1 Ps (0.3 mm). Such ultra-short electron bunches can be produced using a variety of bunching schemes in electron accelerators. We have designed a photocathode RF electron gun, named ECC RF gun, specifically for ultra-short bunch generation. ECC stands for energy chirping cell. This paper describes the brief principle of the ECC RF gun, CTR (coherent transition radiation) observation using Schottky barrier diodes (SBD) and spectrum measurement using interferometry with SBDs. We have successfully confirmed the generation of 0.05-0.3 THz high peak power pulsed CTR. (C) 2014 Elsevier B.V. All rights reserved.

For a longitudinal characterization of an ultra-short electron bunch, an rf-deflector cavity is the best resolution technique that can directly convert longitudinal distribution to transverse. This paper describes the principle of longitudinal diagnostics using an rf-deflector cavity, the design details of an rf-deflector cavity and the results of rf-characteristics for a manufactured cavity. The cavity is based on a rectangular two-cell structure operating on standing wave pi-mode, dipole (TM120) mode at 2856 MHz. We have confirmed using HFSS simulation that this cavity can produce a deflecting voltage of 1.63 MV with an input rf-power of 750 kW. The results of low power rf-measurement of the manufactured cavity show an effective deflecting voltage of 1.00 MV which corresponds to a temporal resolution of 58 fs (rms) (250 fs/mm on the profile monitor) with 750 kW input rf-power, drift length L of 1 m and initial size sigma(off) of 230 mu m. These results indicate that we have successfully achieved our target: temporal resolution of less than 100 fs with an electron bunch with energy of 4.5 MeV and charge of 100 pC. (C) 2014 Elsevier B.V. All rights reserved.

Function-graded proton exchange membranes (G-PEMs) based on poly(tetrafluoroethylene-co-hexafluoropropylene) were fabricated for direct methanol fuel cells (DMFCs) via electron beam-grafting using the heterogeneous energy deposition technique. The G-PEMs had a water uptake gradient in the proton transfer direction, originating from the sulfonic acid group gradient. The distribution of sulfonic acid groups in the various G-PEMs was evaluated using X-ray photoelectron spectroscopy. Four types of PEMs (flat-type, strong-gradient, meso-gradient, and weak-gradient types) were fabricated. By varying the direction of the G-PEMs, the methanol permeation test and DMFC operation were performed with two orientations of the sulfonic acid group gradient, decreasing from the methanol injection (anode) side (decrease-type) or the other (cathode) side (increase-type). The methanol permeability of the strong-gradient, meso-gradient, and weak-gradient G-PEMs was lower than that of Nafion (R) 117 and the flat-type PEM. The increase-type orientation of the strong-gradient G-PEM resulted in the lowest methanol permeability. The DMFC performance of the G-PEMs was influenced by the thickness direction, such as decrease-type and increase-type. The performance of the decrease-type assembly was higher than that of the increase-type. The decrease-type assembly with P-200 k (weak-gradient G-PEM) exhibited the highest performance of the fabricated PEMs, comparable to that of Nafion (R) 117.

We present a new design for a rf electron gun to be used in ultrashort (similar to 1 ps) electron bunch generation. Using both simulation and measurement we evaluated the principle of this new type rf gun and were able to confirm an ultrashort bunch generation. During simulation, a bunch length of less than 100 fs(rms) with a 100 pC/bunch charge was confirmed at the optimum operating condition. The principle is to produce a linearly distributed longitudinal phase space by using an attached output cell specially designed for energy chirping. Such phase space distribution can be rotated by the velocity difference in the bunch. We already fabricated an energy chirping cell attached rf gun and successfully observed 0.2 THz coherent synchrotron radiation, which corresponds to less than 500 fs bunch. Such an electron gun can be used as a compact THz light source and a new electron injector with an ultrashort bunch.

EUV, X-ray and EB mainly induce ionization in resist materials and its energy deposition process is different from ArF exposure. Linear energy transfer (LET) effect for resist sensitivity is very important issue from the viewpoint of radiation induced chemical reactions for high-volume nanofabrication. Therefore the knowledgebase of radiation chemistry is required for understanding the resist performances for EUV lithography. In order to acquire the knowledge of resist materials for EUV / EB lithography from a viewpoint of the free-volume, the positron annihilation lifetime spectroscopy was carried out using positron probe microanalyzer (PPMA) installed at AIST. The size of free-volume can be evaluated from the lifetime of ortho-Positronium (o-Ps). The lifetime and intensity of o-Ps in EB-exposed positive-tone non-chemically amplified (non-CA, ZEP) and CA (UV-III) EUV / EB resists were observed. Moreover, to evaluate the relationship between line edge roughness (LER) and free-volume, EB lithography was carried out, and then sensitivities (E0 and Esize) and LER were measured. For both non-CA and CA resist materials, the changes of free-volume due to evaporation of outgas, polarity change or chain scission would hardly influence on their LER and resolution. © 2014 SPIE.

Copyright © 2014 CC-BY-3.0 and by the respective authors. A prototype solid state picosecond laser is reported for single shot laser-Compton bio-imaging applications. The target specification is 1J, 1ps at 120Hz with good beam quality for precise pointing to 10 μm focused 43MeV electron beam with 1nC charge. 0.1J stretched pulse is obtained from a thin disc Yb:YAG laser, and amplified through a cryogenically cooled Slab Yb: YAG module in a multipass configuration. Temperature dependent gain characteristics is analysed and concluded as the designed optimization is sufficient for long time stable operation for the laser-Compton imaging.

Copyright © 2014 CC-BY-3.0 and by the respective authors. We have been studying on a system to measure the length of electron bunch generated by a photocathode rf electron gun at Waseda University. We adopted the rf-deflector system which can convert the longitudinal distribution to transverse by sweeping the electron bunch. By using HFSS, we optimized the design of the 2 cell rf-deflector which is operating on π-mode, dipole (TM210) mode at 2856 MHz. The fabrication and the tuning of the rf deflector have successfully processed. We have installed the rf-deflector in the accelerator system of Waseda University, and performed the measurement of the bunch length. It is confirmed that this rf-deflector has the temporal resolution of 167fs with 700kW supply when the beam energy is 4.8MeV. This means that our rf-deflector system has possibility to measure the ultra-short bunch length. In this conference, the rf-deflector system in Waseda University, the result of the bunch length measurement, the performance of the rf-deflector and the future plan will be reported.

Copyright © 2014 CC-BY-3.0 and by the respective authors. In laser produced plasma EUV source, high intensity pulse CO&lt;inf&gt;2&lt;/inf&gt; laser is essential for plasma generation. To achieve high conversion efficiency and stable EUV power, we desire to measure laser profile at the collision point. However, focused laser profile has not been observed directory by existing techniques. We have been developing laser profiler based on laser Compton scattering. Laser profile can be measured by scanning focused electron beam while measuring Compton scattering signal. This method is suitable for a high intensity laser, but very small spot size of electron beam is required. To achieve small spot size, we use S-band photocathode rf gun and specially designed solenoid lens. The beam size was simulated by General particle tracer (GPT) and directory measured by Gafchromic film HD-810. We have succeeded in observing minimum beam size of about 20μm rms. We are preparing beam scanning system, pulse CO&lt;inf&gt;2&lt;/inf&gt; laser and a detector for Compton signal. In this conference, we will report the results of focused electron beam measurement and future prospect.

Copyright © 2014 CC-BY-3.0 and by the respective authors. We have been developing an Energy-Chirping-Cell attached RF electron gun (ECC-rf gun) for generating ultrashort electron bunches. ECC-rf gun has extra cell at the end of gun cavity in order to chirp the bunch energy. Such a bunch can be compressed by the velocity difference though the drift space. We have already installed it to our accelerator system and successfully observed a coherent synchrotron/transition radiation at 0.3 THz. It is clear that the bunch length was short enough to generate 0.3 THz, which corresponds to less than 500 fs bunch length was achieved if we assume the gaussian shape. In this conference, the principle of ECC-rf gun, the recent results of bunch length measurement and future prospective will be presented.

Copyright © 2014 CC-BY-3.0 and by the respective authors. We have been studying a compact electron accelerator based on an S-band Cs-Te photocathode rf electron gun at Waseda University. We are using this high quality electron bunch for many application researches. It is necessary to measure the bunch length and temporal distribution for evaluating application researches and for improving an rf gun itself. Thus, we adopted the rf deflector system. It kicks the electron bunch with resonated rf electromagnetic field. Using this technique, the longitudinal distribution is mapped into the transverse space. The rf deflector has a 2-cell standing wave π-mode structure, operating in TM210 dipole mode at 2856 MHz. It provides a maximum vertical kick of 1.00MV with 750 kW input rf-power which is equivalent to the temporal resolution of around 58 fs bunch length. In this conference, we report the details of our rf deflector, the latest progress of longitudinal phase space diagnostics and future prospective.

Copyright © 2014 CC-BY-3.0 and by the respective authors. EUV source community is interested in evaluating an alternative method based on high repetition rate FEL, to avoid a risk of the potential source power limit by the plasma based technology. Present SASE FEL pulse (typically 0.1mJ, 100fs, 1 mm diameter) has higher beam fluence than the resist ablation threshold, and high spatial coherence which results in speckle and interference patterns, and random longitudinal mode spikes of high peak power micro pulses, which is not favourable to resist chemistry. This paper discusses on the required technological assessment and lowest risk approach to construct a prototype, based on superconducting linac and cryogenic undulator, to demonstrate a MHz repetition rate, high average power 13.5nm FEL equipped with specified optical components, for best optimization in EUVL application, including a scaling to 6.7nm wavelength region.

Energy Chirping Cell attached rf gun (ECC rf gun) is a photocathode rf gun specialized for ultra-short bunch generation. This ECC rf gun has been made with the collaboration of High Energy Accelerator Research Organization (KEK) [1] [2]. Although the bunch length could be controlled by the laser pulse width, the bunch length ends up to be more than 1 ps due to space charge effect when using a femto-second laser and a normal 1.6 cell cavity. Concerning this phenomenon, ECC is attached right after the 1.6 cell so that the electron bunch would be compressed after the electron bunch is accelerated around 5 MeV. The roll of ECC is to chirp the energy with the linear part of the rf electric field. The electron bunch would be compressed by velocity difference as it drifts. Simulation results from PARMELA and GPT show that the ECC rf gun can accelerate an 100 pC bunch with the bunch length less than 100 fs. We already manufactured this ECC rf gun and installed in our system. We demonstrated the ultra-short bunch by measuring the coherent THz light by synchrotron radiation and transition radiation. In this conference, we will report the results of ultra-short bunch generation experiments, and future plans. Copyright © 2013 by JACoW.

A high-intensity laser is essential for plasma generation for EUV (Extreme Ultraviolet) lithography, which is studied as the next generation of ultra-fine semiconductor lithography. Nevertheless, there is no way to directly measure profile of high-intensity laser at the present day. Therefore, we have been developing a method for measuring high-intensity laser profile based on the laser- Compton scattering using Cs-Te photo cathode RF-Gun at Waseda University. Specifically, laser profile is obtained by scanning the electron beam which is focused to about 10 μm by solenoid lens. We have simulated beam size focused by solenoid lens using tracking code GPT (General Particle Tracer) and optimized the beam parameter to obtain beam size of 10 μm. Then, we have installed solenoid lens and generated focused beam. We measured beam size using radiochromic film called GAFCHROMIC dosimetry film type HD-810. In this conference, we will report the result of GPT simulations, beam size measurements, the present progress and future prospects.

We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. We already obtained a pulse-train x-rays through the laser-Compton scattering between a multi-bunch electron beam and an optical super-cavity. And also, we performed a X-ray imaging via laser-Compton X-ray. On these successful results, we decided to upgrade our system for increasing X-ray flux by 3-order of magnitudes for practical use. For an optical cavity, we designed 4-mirrors bowtie cavity in order to increase the power. On the other hand, electron accelerator was also upgraded to increase the bunch number in the train. We use 3.6cells rf-gun and 12cell standing wave booster linac. As a result, 2-order increase of X-ray flux was achieved. Design of upgraded our laser-Compton X-ray source, the results of X-ray experiments and future prospective will be presented at the conference. Copyright © 2013 by JACoW- cc Creative Commons Attribution 3.0 (CC-BY-3.0).

We have been developing a laser-Compton X-ray source using an optical enhancement cavity. We have studied 1um pulse laser storage in optical cavity and use for the experiments. Usage of 10 um laser for optical enhancement cavity will increase the X-ray energy region of one laser-Compton X-ray source, so that we decided to develop the optical cavity for CO2laser. We have designed external optical cavity for CO2laser commercially available optics and verified the enhancement of CO2laser in external enhancement optical cavity, and measured fundamental parameters such as finesse, matching efficiency, and enhancement factor. We have already achieved 475 of finesse, 43 of enhancement, and tested non-planer cavity, which storages two circular polarization separately. In this conference, we will report the design and experimental results of CO2laser storage cavity and also some future prospects. Copyright © 2013 by JACoW- cc Creative Commons Attribution 3.0 (CC-BY-3.0).

最近になって,ポストEUVリソグラフィ露光光源波長として,6.x nmの波長が注目され始めている.ハーフピッチが16nm以下になると,これまで開発されてきた13.5nmの光源では開口数や多層膜鏡,マスクまで設計から製造まで高度に改善することが求められるからである.そこで,解像度を上げるために,更なる短波長光源が必要になってくる可能性があるというわけである.ここでは,ポストEUV光源としての波長6.x nm光源の進展について紹介することにする.

We have been developing an S-band Cs-Te photocathode rf electron gun system for various application researches such as pulse radiolysis experiments and laser Compton scattering experiments at Waseda University. These researches demande for high quality and well controlled electron beam. In order to measure the ultra-short electron bunch, we decided to use rf-deflector cavity, which can convert the longitudinal distribution to the transverse. With this technique, the longitudinal bunch profile can be obtained as the transverse profile on the screen monitor. We used the 3D electromagnetic field simulation codes HFSS for designing rf-deflector cavity and GPT for beam tracking. The cavity has two-cell structures operating on π-mode, standing wave, dipole(TM120)mode at 2856 MHz. We have confirmed on HFSS that two-cell rf-deflector cavity can produce 660 G magnetic field per cell on beam line with 750 kW input rf-power. This field strength is equivalent with our target, which is 100 fs bunch length measurement at 4.3 MeV. In this paper, we will present the cavity structure design, and the measurement results of manufactured cavity. © 2013 IEEE.

The different exposure sources induce a different energy deposition in resist materials. Linear energy transfer (LET) effect for resist sensitivity is very important issue from the viewpoint of radiation induced chemical reactions for high-volume nanofabrication. The sensitivities of positive tone non-chemically (non-CA, ZEP) and chemically amplified (CA, UV-3) resist materials are evaluated using various ionized radiation such as EUV, soft X-rays, EB and various ion beams. Since the notations of sensitivity of resist vary with exposure sources, in order to evaluate systematically, the resist sensitivity were estimated in terms of absorbed dose in resist materials. Highly-monochromated EUV and soft X-rays (6.7 nm - 3.1 nm) from the BL27SU of the SPring-8, high energy ion beams (C6+, Ne10+, Mg12+, Si14+, Ar18+, Kr36+ and Xe54+) with 6 MeV/u from MEXP of HIMAC, EB from low energy EB accelerator (Hamamatsu Photonics, EB-engine(R), 100 kV) and EB lithography system (30 keV and 75keV) were used for the exposure. For non-CA and CA resist materials, it was found that LET effects for sensitivity would be hardly observed except for heavier ion beams. Especially, in the case of the high energy ion beam less than Si14+ with 6 MeV/u, it is suggested that the radiation induced chemical reaction would be equivalent to EUV, soft X-ray and EB exposure. Hence, it indicates that the resist sensitivity could be systematically evaluated by absorbed dose in resist materials.

Extreme ultraviolet lithography (EUVL) at 13.5 nm will soon be applied in high-volume manufacturing of semiconductors, as a replacement to the ArF excimer laser immersion lithography. Recently, the potential application of exposure wavelengths of 6.x nm (particularly 6.6-6.8 nm) has been discussed as EUVL extension. The 6.x nm exposure source is currently under development, therefore screening of resists with conventional exposure tools will accelerate the selection or novel development of high sensitivity resists for 6.x nm EUVL. In the present study, the sensitivities of a chemically amplified (CA) resist (OEBR-CAP112) and non-CA resists (ZEP520A and poly(methyl methacrylate)) were evaluated with 30 keV and 75 keV electron beam lithography (EBL) tools. In terms of radiation chemistry, the obtained dose/sensitivities (mu C cm(-2)) were converted into the absorbed doses (Gray; Gy = J kg(-1)). If EB-and EUV-induced chemical reactions are the same, the required absorbed doses for EB and EUV would be similar values. The sensitivities for EUV/soft X-rays including 6.x nm were predicted assuming the required absorbed doses in a resist would show similar values for both EB and EUV. We investigated precise sensitivities of the resists for EUV/soft X-rays including 6.7 nm using highly-monochromated synchrotron radiation. For both CA and non-CA resists, the predicted and experimentally obtained sensitivities agreed well with each other. These results suggested that almost the same chemical reactions are induced in resists for both EUVL and EBL. Hence, it was found that we can predict the resist sensitivities for EUV/soft X-rays at any exposure wavelength from the exposure results for EBL.

This paper describes a design and performance of a three-dimensional 4-mirror optical cavity for development of intense photon sources by laser-Compton scattering. We achieved the finesse of 4000 and average power of 2.6 kW in the cavity with the vertical laser beam spot size of 13±1μm in σ at the laser-electron interaction point. As a result, we observed 124±1 photons with average energy of 24 MeV per beam crossing, which corresponds to the generation of 2.7×108 photons per second. © 2013 Elsevier B.V.

Electrons were irradiated to low-density polyethylene (LDPE), polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and syndiotactic polystyrene (SPS). Many electrons were back scattered and large numbers of electrons and holes were generated in the film by ionization. Since the amount of negative charge observed under short-circuit after the irradiation is significantly smaller than the electron fluence, most electrons and holes generated by the irradiation were either recombined or transported to the electrodes. The amount of negative charge gradually decreases monotonically, showing the order of the decay speed, PI &gt
LDPE &gt
PET &gt
SPS &gt
PEN. The conductivity also shows the same order. When a dc voltage is applied to the sample, in which electrons and holes were generated abundantly by ionization, the electric field is enhanced significantly at the two electrodes due to the presence of positive charge near the cathode and negative charge near the anode. © 2013 IEEE.

We have been developing an S-band Cs-Te photocathode rf electron gun system for various application researches such as pulse radiolysis experiments and laser Compton scattering experiments at Waseda University. These researches demande for high quality and well controlled electron beam. In order to measure the ultra-short electron bunch, we decided to use rf-deflector cavity, which can convert the longitudinal distribution to the transverse. With this technique, the longitudinal bunch profile can be obtained as the transverse profile on the screen monitor. We used the 3D electromagnetic field simulation codes HFSS for designing rf-deflector cavity and GPT for beam tracking. The cavity has two-cell structures operating on pi-mode, standing wave, dipole(TM120)mode at 2856 MHz. We have confirmed on HFSS that two-cell rf-deflector cavity can produce 660 G magnetic field per cell on beam line with 750 kW input rf-power. This field strength is equivalent with our target, which is 100 fs bunch length measurement at 4.3 MeV. In this paper, we will present the cavity structure design, and the measurement results of manufactured cavity.

We have been developing an MRT (Microbeam Radition Therapy) based on Cs-Te photo-cathode RF-Gun at Waseda University. MRT is proposed to treat tumors by using array of several micro-meter parallel beams. In this therapy, irradiated normal tissue repairs itself, by contrast, even a non-irradiated tumor tissue dies. In the other words, the microbeam enhances the radiation sensitivity difference between normal and tumor issues. Therefore, MRT is considered one of the most useful tumor therapies in the future. We have generated electron microbeam by tungsten collimator slit and analyzed their dose distribution in air and in the PMMA phantom. We have used radiochromic film called GAFCHROMIC dosimetry film type HD-810 to measure them. We have compared these experimental results with Monte Carlo simulation of the dose distribution using the EGS5 code. In this conference, we would like to report the electron microbeam procedure, optimization of irradiation condition and evaluation of microbeam specifications. Coyright © 2012 by IEEE.

The high-power terahertz time-domain spectroscopy (THz-TDS) has been developed on the basis of a compact S-band electron linac at AIST, Japan. It is strongly expected for inspection of dangerous materials in the homeland security field. THz radiations are generated in two methods with the ultra-short bunch. One is THz coherent synchrotron radiation (THz-CSR). The other is THz coherent transition radiation (THz-CTR). In the preliminary experiment to obtain the characteristics of THz-CTR, it was observed that the focused THz-CTR had the donut profile in the transverse field due to its initial radial polarization. It was considered to be z-polarization at the focus point. In case of the THz-TDS experiment, THz-CTR was controlled to be linearly polarized with the polarizer and focused to an electro optical (EO) crystal to obtain a THz temporal waveform using EO sampling method. It leads to THz spectrum with Fourier transform. In this paper, we will describe details of our linac and results of the THz-CTR-TDS experiment. Copyright © 2012 by IEEE.

Various species of high intensity highly charged state heavy ion beams with smallemittance are required in many fields including particle physics, medical uses, inertialfusion, and simulator of space radiations. Direct Plasma Injection Scheme (DPIS), we havedeveloped for several years, is a unique scheme to provide heavy ion beams to meet theabove requirements. A high-density plasma created by a laser ablation with an initial driftvelocity flies to entrance of a Radio Frequency Quadrupole (RFQ) LINAC; ions will beseparated from plasma via high voltage at the inside of the RFQ LINAC. Then ions arecaptured by the RF buckets and are accelerated remaining high current over 10mA. In thepast, we had accelerated carbon4+, carbon5+, and carbon6+ using a RFQ with partiallymodulated vanes. Due to the un-modulated section of the electrodes, accelerated beams werenot bunched. In 2011, we replaced the vanes with a newly designed one. The designed chargeto mass ratio (q/A) is 1/6 and the output energy is 270 keV/u. The beam commissioning withcarbon 4+ was successfully carried out. In the next step we&#039;ll try to accelerate carbon 2+(q/A=1/6), which is to demonstrate the feasibility of the Ag+15 ion acceleration. Copyright© 2012 by IEEE.

At Waseda University, various researches are done using a photocathode rf electron gunwith a 1.6 cell cavity. Now we are developing a new rf cavity specialized for producing anultra-short electron bunch, with the collaboration of High Energy Accelerator ResearchOrganization (KEK) [1]. We have used SUPERFISH for designing the new rf cavity and PARMELAfor beam tracking. The new rf cavity has an extra cell following the 1.6 cell. The extracell can chirp the energy of electron bunch so we call it ECC (Energy Chirping Cell). ECCchirp the energy because we shortened the length of iris just before the ECC and also thelength of ECC itself. Moreover, electric field in ECC is made to be stronger than others.We have confirmed on PARMELA that ECC-rf-gun can generate an 100pC electron bunch less than100fsec with the energy of 4.5MeV at about 2.5m away from the cathode. Such an ultra-shortelectron bunch enables us to generate a coherent terahertz light using ultra-short electronbunch by synchrotron radiation or transition radiation. In this report, we would like tointroduce the detail of the design of this new ECC-rf-gun, the present progresses andfuture prospects. Copyright © 2012 by IEEE.

We are developing a ILC polarized positron source based on the laser-Comptonscattering. We have already performed a photon generation experiment at the KEK-ATF using aFabry-Perot type 2-mirror laser pulse stacking cavity [1]. The laser pulses are accumulatedand their power was enhanced in the Fabry-Perot cavity. In order further improveperformance of the laser power enhancement, a new three dimensional 4-mirror cavity isdesigned. In this article, we report status of the photon generation experiment. Copyright© 2012 by IEEE.

We have been developing a pulsed-laser storage technique in a super-cavity for acompact x-ray sources. The pulsed-laser super-cavity enables to make high peak power andsmall waist laser at the collision point with the electron beam. Recently, using 357 MHzmode-locked Nd:VAN laser pulses which stacked in a super-cavity scattered off a multi-bunchelectron beam, we obtained a multi-pulse xrays through the laser-Compton scattering. Then,we performed a X-ray imaging via laser-Compton X-ray. The images have edge enhancement byrefraction contrast because the X-ray source spot size was small enough. This is one of theevidences that laser-Compton X-ray is high quality. Our laser-Compton experimental setup,the results of Xray imaging and future prospective will be presented at the conference.Copyright © 2012 by IEEE.

The performance of a polymer electrolyte fuel cell (PEFC) was affected by the thickness of the thin proton exchange membrane (PEM). The PEMs with the different thickness were prepared by radiation induced grafting of styrene into the radiation-cross-linked polytetrafluoroethylene (RX-PTFE) membrane prepared from PTFE dispersion, and then sulfonated. The wet thicknesses of the obtained thin PEMs were lower than 25 mu m. A PEM based on a 50 mu m PTFE film, with the wet thickness of 73 mu m, was also prepared under the same procedure for the comparison. The obtained PEMs were characterized in term of gas cross-over. The surface of platinum / carbon electrodes was coated with Nafion (R) dispersion, and then membrane electrode assembles (MEAs) were prepared by the hot-pressing. The polarization curves and electrochemical impedances of the thin PEMs in a single fuel cell were analyzed. As a result, the cell performance of the MEA based on thinner PEM tended to give higher power density and current density. On the other hand, the performance of the thinnest PEM (13 mu m) decreased, and the MEA based on the thinner PEM gave the lower open circuit voltage (OCV) due to the higher gas cross-over. Thus, the thin PEM based on RX-PTFE had shown a high performance at the suitable thickness.

Laser-Compton Scattering (LCS) is one of the most feasible techniques for high quality, high brightness, and compact X-ray source. High energy electron beam produced by accelerators scatters off the laser photon at a small spot. As a laser target, we have been developing a pulsed-laser storage cavity for increasing an X-ray flux. The X-ray flux was still inadequate that was 2.1x10(5)/sec, however, we performed first refraction contrast imaging in order to evaluate the quality of LCS X-ray. Edge enhanced contrast imaging was achieved by changing the distance from sample to detector. The edge enhancement indicates that the LCS X-ray has small source size, i.e. high brightness. We believe that the result has demonstrated good feasibility of linac-based high brightness X-ray sources via laser-electron Compton scatterings.

We have been developing an S-band photocathode rf electron gun at Waseda university. Our rf-gun cavity was firstly designed by BNL and then, modified by our group. In this paper, we will introduce a newly designed rf-gun cavity with energy chirping cell. To generate an energy chirped electron bunch, we attached extra-cell for 1.6cell rf-gun cavity. Cavity design was done by Superfish and particle tracking by PARMELA. By optimizing the chirping cell, we observed linear chirped electron bunch. The front electron have lower energy than rear. Then transporting about 2m, the bunch can be compressed down to 200fsec electron bunch with the charge of 160pC. This ultra-short bunch will be able to use for generating CSR THz radiation, pumping some material to be studied by pulse radiolysis method, and so on. In this conference, the design of chirping cell attached rf-gun, the results of tracking simulation and plan of manufacturing will be presented. Copyright © 2011 by IPAC&#039;11/EPS-AG.

At Waseda University, we have been studying a high quality electron beam generation and its application experiments with a Cs-Te photocathode RF-Gun. To generate more intense and stable electron beam, we have been developing the cathode irradiating UV laser which consists of optical fiber amplifier and LD pumped amplifier. As the result, more than 100 multi-bunch electron beam with 1nC each bunch charge was obtained. However, it has to be considered that the accelerating voltage will decrease because of the beam loading effect. So we have studied the RF amplitude modulation technique to compensate the beam energy difference. The energy difference will caused by transient accelerating voltage in RF-Gun cavity and beam loading effect. As the result of this compensation method, the energy difference has been compensated to 1%p-p, while 5%p-p without compensation. Copyright © 2011 by IPAC&#039;11/EPS-AG.

In usage of radiation, it is important to study the process of chemical effects of ionizing radiation in a material. Pulse radiolysis is a method to trace these rapid initial chemical reactions by ionizing radiation. As a pump beam, we are using about 4 MeV electron beam. In nanosecond timescale pulse radiolysis, it is required the stable probe light of a broad spectra. And especially in picosecond timescale pulse radiolysis, probe light should have short pulse width to use stroboscopic method. Therefore, in order to develop a unified timescale experimental system, we developed Supercontinuum (SC) light as a probe light, which is generated by nonlinear optical process of short pulse IR laser in photonic crystal fiber (PCF). To apply SC light as a probe light of pulse radiolysis, we measured its properties. We tried to measure the absorption spectra of hydrated electron by SC light. Then we successfully observed good signal-noise ratio data both in nanosecond and in picosecond experiment with the same system. In a further attempt, we succeeded to improve stability of SC light. Copyright © 2011 by IPAC&#039;11/EPS-AG.

We have been developing a photocathode rf gun. The rf gun with multi cell can produce a high energy electron beam, so it may be used for numerous applications such as medicine and industry. At the Laser Undulator Compact X-ray source facility, called LUCX, we have developed a compact X-ray source based on inverse Compton scattering [1]. An S-band 3.5 cell rf electron gun which is 20 cm long can produce a high quality electron beam with energy of 8.7 MeV. According to the simulation, the emittance of 3.5 cell rf gun is as low as that of 1.6 cell rf gun. The electromagnetic design has been performed by the code SUPERFISH, and the particle tracing by PARMELA. The new rf gun is already installed and produced a high quality electron beam with energy of 8.7 MeV. As a consequence of the substantial efforts of developing rf cavity, we decide to make a compact RF accelerating structure with more cell for achieving a smaller system. The measurement results of using the 3.5 cell rf gun, the design of 12 cell booster cavity, and current status of 12 cell cavity manufacturing will be presented at the conference. Copyright © 2011 by IPAC&#039;11/EPS-AG.

At Laser Undulator Compact X-ray Source (LUCX) facility at KEK, we have developed a RF gun with increased mode separation. Using this RF gun we have successfully generated a bunch train of 300 bunches per train with 160 nC total charge and with peak to peak energy difference less than 0.85% at 5.2 MeV. We plan to generate and accelerate 8000 bunches per train with 0.5 nC per bunch. These bunches will then collide in the collision chamber with laser pulses to produce soft x-ray. After successful results from above work, we take next step and are now designing and fabricating a new 3.5 cell RF gun and a high gradient standing wave linac to achieve 50 MeV beam with 8000-bunches per train. This compact source will be used for future research. This paper details achieved results with existing gun for generation of long bunch train and lists out proposed activity.

The chemical structures of various ion-beam irradiated isotactic-polypropylene samples were studied. Results of micro-Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy suggest not only the linear energy transfer, but also the fluence is effective in local transformation of the isotactic-polypropylene. (C) 2010 Elsevier Ltd. All rights reserved.

Novel proton exchange membranes (PEMs) with functionally gradient ionic sites were fabricated utilizing low energy electron beam (EB) irradiations. The low energy electron beam irradiation to polymer membranes possessed the property of gradient energy deposition in the membrane thickness direction. In the process of EB grafting of styrene onto base films, selective ranges of the gradient energy deposition were used. Micro FT-IR spectra showed that the simulated energy deposition of EB irradiation to base polymer membranes in the thickness direction corresponded to the amount of styrene grafted onto EB-irradiated films. After sulfonation, a functionally gradient ionic site PEM (gradient-PEM) was prepared, corresponding to EB depth-dose profile. The functionally gradients of ionic sites in the gradient-PEM and flat-PEM were evaluated with XPS and SEM-EDX. The results of XPS and SEM-EDX suggest that the prepared gradient-PEM had a gradient sulfonated acid groups. In addition, the polarization performance of MEA based on gradient-PEM was improved in high current density. It was thought that water uptake gradient could have a function to prevent flooding in the MEA during FC operation. Thus, the functionally gradient-PEMs could be a promising solution to manage the water behavior in MEA. (C) 2010 Elsevier Ltd. All rights reserved.

The increasing density of semiconductor devices has required the development of high resolution exposure techniques. The miniaturization of feature sizes has been achieved mainly by shortening the exposure wavelength. Extreme ultraviolet (EUV) lithography at 13.5 nm exposure wavelength will be introduced into pilot lines in 2011, and high volume manufacturing is expected to be started in 2013/2014. Furthermore, the possibility of extending EUV lithography down to sub 5 nm has been proposed as next-generation lithography, by reducing the exposure wavelength to 6.x nm. ASML has estimated the throughput of exposure system for 6.x nm EUV lithography is comparable with 13.5 nm lithography, based on the experiments such as reflective multilayer optics. However, the estimation has not included the sensitivities of resist materials, which is one of the most important criteria for the practical lithography systems. Here, the sensitivities of several kinds of typical resists in EUV/soft X-ray wavelength down to 3.1 nm were actually evaluated by experiments. The sensitivities of resist materials were roughly proportional to the absorbed dose calculated by line absorption coefficients of resists. The dependence of the exposure wavelength on EUV resist sensitivity could be theoretically predicted for the next-generation lithography, if sensitivity at a certain EUV wavelength like 13.5 nm is experimentally obtained.

Functionalized poly(tetrafluoroethylene-co-hexafluoropropylene (FEP)) was fabricated by electron beam (EB) induced grafting technique and chemical sulfonation treatment. The functionalized FEP (s-FEP) films were immersed in the silver nitrate (AgNO3) solution under ambient condition, to exchange on ionic sites from proton ion-form to Ag+ ion-form, and then the Ag-formed s-FEP polymers were obtained. Ag-formed s-FEP was irradiated with 30 keV Ga+ focused ion beam (FIB) and 6 MeV/u dispersed Ne10+ ion beam (DIB). The irradiated areas were evaluated by a scanning electron microscopy (SEM) with an energy dispersive X-ray spectroscopy (EDX). In both cases of FIB and DIB irradiations, the nano-scale particles were appeared on the surface of irradiated areas. From the results of EDX analysis for the particles, the peaks which were assigned to silver atoms were clearly detected, and peak intensities were higher than un-irradiated one. It is suggested that the Ag+ ions would be reduced by ion beam irradiation and appeared as silver nano-scale particles with pure silver metal and its oxidative chemical compounds.

We have been studying a pump-probe pulse radiolysis as an application of the S-band photo cathode RF-Gun. Pump-probe spectroscopy is well-known method of pulse radiolysis measurement. We had used 5MeV electron beam obtained from the photo cathode RF-Gun as a pump beam, and used the white light emitted from Xe flash lamp or generated by self-phase modulation in the water cell as a probe light. However, the white probe light with high intensity, good stability and broad spectrum is a key issue for pump-probe pulse radiolysis. Supercontinuum light with photonic crystal fiber (PCF) is a new technique of white light generation. Short pulse laser through PCF spreads its spectrum by nonlinear optical effect. Supercontinuum light has very continuous spectrum, and it is studied for various applications recently. For applying supercontinuum light as a probe of pulse radiolysis experiment, we have generated a supercontinuum radiation with 7 picoseconds pulse width IR (1064nm) laser and PCF, and measured its properties. The experimental results of supercontinuum generation and design of a supercontinuum based pulse radiolysis system will be presented.

At Laser Undulator Compact Source (LUCX) at KEK, we designed and made a new RF Gun with high mode separation of 8.6 MHz and high Q value as compared to earlier guns. This paper presents fabrication details, low power measurements and tuning procedures followed in making the gun cavity. We also discuss in detail, experimentation done using this gun and show the measurement results. Currently we produce 100 bunch per train but we plan to go for 300 or more bunch per train operation. This will make possible to have higher charge available for laser-beam collisions to generate high flux soft X-rays by Inverse Compton Scattering at our setup.

We have developed a compact X-ray source via inverse Compton scattering between an electron beam and a laser pulse stacked in an optical super-cavity at Laser Undulator Compact X-ray (LUCX) accelerator in KEK. The accelerator consists of a photo-cathode RF-gun and an S-band accelerating tube and now produces the multi-bunch electron beam with 100 bunches, 0.5nC bunch charge and 40MeV beam energy. It is planned to upgrade the RF-gun and the RF system of the accelerator and the super-cavity in order to increase the X-ray yield. The new RF-gun with high mode separation and high Q value and a new klystron for the gun will be installed to provide good compensation with a high-intensity multi-bunch electron beam. A new optical super-cavity consisting of 4 mirrors is also being developed to enhance the stacking power in the cavity and to reduce the laser size at the focal point. The first targets are to produce a multi-bunch electron beam with 3000 bunches, 0.5nC bunch charge and 5MeV beam energy in low energy mode and with 100 bunches, 2nC and 40 MeV in high energy mode to generate X-rays by inverse Compton scattering. In this paper, the status and future plan of the accelerator will be reported.

We will present a design of high brightness light source for EUV lithography mask inspection. The required system parameters are minimum brightness of 2500W/mm2/Sr at 13.5nm/2% bandwidth. Our design consists of superconducting DC RF-gun as a radiator and 10.74nm CO2laser stacked in an optical cavity as a laser undulator. Recent achievements of each component technologies, which is 1.3GHz SC-RF-gun, 10kW average power short pulse CO2laser, and laser storage optical super-cavity, indicate the feasibility of producing required brightness based on laser Compton undulator. Design parameters of high brightness EUV source, the technological gap of the present component technologies and required further developments will be resented at the conference.

At Waseda University, we have been studying a high quality electron beam generation and its application experiments with Cs-Te photocathode RF-Gun. We have already succeeded in generating a stable high-charged single-bunch electron beam. To generate more intense electron beam, we designed a multi-bunch electron linac and developed the multi-pulse UV laser which irradiates to the cathode. The target values of the number of electron bunch and bunch charges are 100 bunches/train and 800pC/bunch, respectively. In addition, we adopted the method of the amplitude modulation of the incident RF pulse to the S-band klystron in order to compensate the energy difference in each bunch because of the slow rise time of acceleration voltage in cavity and beam loading effect in the accelerating structure.

We performed a photon generation experiment by laser-Compton scattering at the KEK-ATF,aiming to develop a Compton based polarized positron source for linear colliders. In the experiment, laser pulses with a 357 MHz repetition rate were accumulated and their power was enhanced by up to 250 times in the Fabry-Perot optical resonant cavity. We succeeded in synchronizing the laser pulses and colliding them with the 1.3 GeV electron beam in the ATF ring while maintaining the laser pulse accumulation in the cavity. As a result, we observed 26.0 +/- 0.1 photons per electron-laser pulse crossing, which corresponds to a yield of 10(8) photons in a second. (C) 2010 Elsevier B.V. All rights reserved.

A laser-driven RF gun with a Cs2Te photocathode, a device modeled after the BNL-IV RF gun, has been in development at KEK since 2002. This gun has been operated as an electron source for the Accelerator Test Facility (ATF) and generates a beam with an operational intensity of up to 3.2 nC per bunch. Based on successful results at the ATF, this gun has been applied several times for new research at universities. From 2002 onwards, successive improvements have been incorporated into newer models of the RF gun. Most recently, in 2008, a new gun incorporating all of the earlier modifications was produced for the ATE Tests have confirmed a significant improvement of the Q-value of the latest model. A typical transverse emittance of 1.3 pi mm mrad has been obtained under the following conditions: solenoid field of 0.18 T, beam intensity of 1.6 nC per bunch, and RF power of 9 MW. This RF gun equipped with the Cs2Te photocathode is being used for the advanced research programs at the ATF. A survey of its performance has recently been completed. (C) 2009 Elsevier B.V. All rights reserved.

Ion-beam irradiation effects on polyimide, Kapton (TM), were studied with respect to optical and electronic properties. Stack films of Kapton (TM) (12.5 mu m thick) were irradiated to various ion beams in air or vacuo at room temperature and subjected to ultraviolet-visible (UV-vis) spectroscopy, and change in absorbance and energy gap is discussed. The UV-vis absorption spectrum, which is assigned to the transition of electrons in benzene rings from pi to pi* orbital, upon He(2+) (6MeV/u) irradiation in air, shifted towards longer wavelength direction for all cases, and the shift was more obvious for higher linear energy transfer (LET) ion beams. The energy gap of the transition was estimated, and the H(+) and He(2+) ion beams caused little change in the transition energy gap Eg, while the heavier ions such as C(6+) and Si(14+) caused more significant decrease. This decrease is assumed to the structural changes around benzene rings, and the infrared spectroscopy revealed breakage in imide groups next to benzene ring in the repeating unit of polyimide. (C) 2009 Elsevier Ltd. All rights reserved.

High-power extreme ultra-violet (EUV) sources are required for next generation semiconductor lithography. We start to develop a compact EUV source in the spectral range 13-14 nm, which is based on a laser Compton scattering between a 7 MeV micro-bucnhed electron beam and a high-intensity CO laser pulse. The electron beam extracted from a DC photocathode gun is micro-bunched using a laser modulation techinque with the Compton wavelength at a harmonic of the seeding laser before the main laser Compton scattering for EUV generation. A considerating scheme for the compact EUV source based on the laser Compton scattering with micro-bunched electron beam and the analytical study of micro-bunch generation are described in this paper. (C) 2009 Elsevier Ltd. All rights reserved.

X-ray generation based on laser-electron Compton scattering is one attractive method to achieve a compact laboratory-sized high-brightness x-ray source. We have designed, built, and tested such a source; it combines a 50 MeV multibunch electron linac with a mode-locked 1064 nm laser stored and amplified in a Fabry-Perot optical cavity. We directly observed trains of pulsed x rays using a microchannel plate detector; the resultant yield was found to be 1.2 x 10(5) Hz in good agreement with prediction. We believe that the result has demonstrated good feasibility of linac-based compact x-ray sources via laser-electron Compton scatterings. (C) 2009 American Institute of Physics. [doi:10.1063/1.3272789]

We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, using 357MHz mode-locked Nd:VAN laser pulses which stacked in a super-cavity scattered off a multi-bunch electron beam, we obtained a multi-pulse x-rays through the laser-Compton scattering. Detecting an x-ray pulse-by-pulse using high-speed detector makes it possible to measure the 3-dimensional beam size with bunch-by-bunch scanning the laserwire target position and pulse timing. This technique has a feasibility of measuring femto-second bunch length by stacking femto-second pulse in an optical cavity. Design study of femto-second laser-wire monitor and the experimental demonstration using pico-second pulse storage and multi-bunch electron beam will be presented at the conference.

A photo-cathode RF-Gun is one of the good alternatives for the electron source, because of its high gradient on the electron emitter causing small beam emittance, and tenability of initial beam profile especially for electron bunch length. Therefore, we are operating as a high brigh-tness short pulse electron source. In last year, we have been developing a high quality electron source based on photo-cathode RF-gun which is newly designed RF cavity and has a Cs-Te cathode with high quantum efficiency [1] [2]. Improved RF-Gun cavity has four compact tuners on each half cell and full cell, which can be tuned the resonance frequency to deform the cavity wall. Also removing the Helicoflex seal and tuning holes, reduction of the dark current is expected. According to these improvements, the Q value and shunt impedance of the new RF-Gun cavity increased 20% compared with the previous RF cavity. In addition, the dark current of cavity was reduced and the good electron beam parameters could be achieved compared with pre-vious RF-Gun with a Cu cathode.

A compact and high quality x-ray source is required for various field, such as medical diagnosis, drug manifacturing and biological sciences. Laser-Compton based x-ray source that consist of a compact electron storage ring and a pulsed-laser super-cavity is one of the solutions of a compact x-ray source. Pulsed-laser super-cavity has been developed at Waseda university for a compact high brightness x-ray source. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. 357MHz mode-locked Nd:VAN laser pulses can be stacked stably in a 420mm long Fabry-Perot cavity with &quot;burst mode&quot;, which means stacking of electron beam synchronized amplified pulses in our R&amp; D. In view of this successful result, we have started an X-ray generation experiment using a super-cavity and a multi-bunch electron beam at KEK-LUCX. Recently, the demonstration experiment between the burst mode pulsedlaser super-cavity and the 100 bunch multi-bunch electron beam is successfully performed. Development of the supercavity and the experimental results of X-ray generationwill be presented at the conference.

We studied gamma-ray generation by the laser-Compton scattering using a Fabry-Perot optical resonant cavity at the KEK-ATF electron storage ring. The laser power was enhanced up to 388 W in the optical resonant cavity with an injection power of 7 W in the ATF operation environments. The yield of photons for a crossing of a laser pulse and an electron bunch was 3.3 +/- 0.6, which was consistent with a numerical estimate. In this paper, we report construction, installation and future prospect toward the polarized positron generation for the International Linear Collider.

Our group at the Laser Undulator Compact X-ray source facility (LUCX), KEK (High Energy Accelerator Research Organization) is performing experiments to generate X-rays by inverse Compton scattering. The system, to generate the X-rays requires a high intensity beam with low emittance. In this research we propose modifications to the existing system to achieve an acceleration of 200 nC in 100 bunches. Specifically, we seek to demonstrate that a new RF gun with high mode separation and high Q value will achieve a beam of good quality. A new RF power system with a modified power delivery scheme provides a good beam loading compensation with a high-intensity multi-bunch electron beam. The acceleration of 200 nC in 100 bunches with low emittance will help increase the intensity of X-rays by inverse Compton scattering. (C) 2008 Elsevier B.V. All rights reserved.

A compact soft X-ray source via inverse Compton scattering has been developed at Waseda University. The energies of the generated X-rays are within "water window" region (250 - 500 eV) and development of a soft X-ray microscope is expected which can get the elemental mapping of carbon and/or nitrogen without dehydration. We have studied to develop a high resolution soft X-ray imaging system with photo resists for nanoscale observation. However, the yield of generated X-rays had been too small for the practical use of the soft X-ray microscopy. To enhance the X-ray yield, we have upgraded the generation system and succeeded in increasing the detected photons 10-fold. Total generated photons were estimated to be over 1.5E+5 photons/s. Also, super-sensitization of photo resists has been attempted to reduce the required X-ray amount. By irradiating quasi-monochromatic X-rays in the water window region from synchrotron radiation at BL12 of the SAGA-LS, the sensitivity of a deep-UV photo resist, TDUR-P722 (Tokyo Ohka Kogyo Co., Ltd) was evaluated. After UV light (including 254 nm) exposure up to the sensitivity threshold and baking as PEB process, it was found that the resist becomes more sensitive. This UV "pre-exposure" method reduced the required 400 eV X-ray amount by over 65%.

It was demonstrated that the nano / microfabrication and functionalization for crosslinked Polytetrafluoroethylene (RX-PTFE) were carried out using focused ion beam (FIB). The fine pattern of the regularly nano-scale square array holes with 300 nm square size were fabricated by FIB direct etching. The fabricated samples were functionalized by post grafting reaction using trapped free radicals induced by FIB irradiation, and the samples were successively sulfonated. The obtained samples were treated by the mixture solution of KOH/KCI to make potassium form, and observed by FE-SEM with EDX spectroscopy. The signals correspond to potassium atom were detected at the holes in fabricated area of RX-PTFE. On the other hand, the signals of potassium formed sulfonic group were hardly detected at the distance of 10 mu m from the hole's center in the fabricated area.

Perfluoro-sulfonic acid (PFSA) membranes were exposed to UV for the improvement of surface adhesion property. The photochemical effect of PFSA was evaluated by UV-visible spectroscopy. The changes of the chemical structure of UV-exposed PFSA were studied by electron spin resonance (ESR) and Fourier transform infrared (FTIR) spectroscopies. ESR spectra revealed the presence of peroxy radicals. Moreover, the results of FTIR would be indicating the decomposition of side chains of PFSA. To evaluate the adhesion properties after UV exposure, the shearing stresses of laminations were measured. The lamination of UV-exposed PFSA showed higher adhesion property than that of unexposed PFSA. A membrane electrode assembly (MEA) consisting of UV-exposed PFSA was fabricated by a hot-press method for the fuel cell operations. The obtained MEA showed higher cell performance than that of the MEA of unexposed PFSA.

京都大学光陰極高周波電子銃開発の現状と、京都大学自由電子レーザー施設へ導入した際の性能予測について報告する。

A 1.6 cell S-band photo-cathode RF-Gun is one of the good alternatives of the short pulse electron source. Therefore, we are operating as a high brightness short pulse electron source for studying a reaction of radiation chemistry [1], an inverse Compton scattering at Waseda University [2] and as an injector at KEK-ATF. To improve an electron beam quality and reduce a dark current, our group decided to improve the RF-Gun cavity. The resonance frequency tuning of the half cell of existing RF-Gun was performed by the torque control of Helicoflex seal on the cathode plate and two moving rod type tuners with a tuning hole were installed on the full cell. Newly designed RF-Gun cavity has four compact tuners on each cell, which can be tune the frequency to deform the cavity wall, to remove the Helicoflex seal and tuning holes that were considered to be the major cause of electric discharge and/or dark current source [3]. According to these improvements, the Q-value and shunt impedance of the cavity is 20% larger than that of existing guns. As the result, the reduction of dark current is demonstarated and the beam energy is reached up to 5.5MeV at 10MW RF input.

A compact and high quality x-ray source is required for various field, such as medical diagnosis, drug manufacturing and biological sciences. Laser-Compton based x-ray source that consist of a compact electron storage ring and a pulsed-laser super-cavity is one of the solutions of a compact x-ray source. Pulsed-laser super-cavity has been developed at KEK-ATF for a compact high brightness x-ray source. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, 357MHz mode-locked Nd:VAN laser pulses can be stacked stably in a 420mm long Fabry-Perot cavity with 2.5kW average power in our R&amp;D. On the other hand, we have succeeded to stack the pulsed amplified laser in the super-cavity. This indicates that the number of X-ray is multiplied due to the gain in the amplification system to synchronize the pulsed pump to the beam. In view of this successful result, we have started an X-ray generation experiment using a super-cavity and a multi-bunch electron beam at KEK-LUCX. Development of the super-cavity and the results of X-ray generation experiment will be presented at the conference.

A compact X-ray source via laser Compton scattering is required for biological, medical and industrial science because it has many benefits about generated X-rays such as short pulse, quasi-monochromatic, energy tunability and good directivity. Our X-ray source is conventionally the single collision system between an electron pulse and a laser pulse. To increase X-ray yield, we have developed a multi-collision system with a multi-bunch electron beam and a laser optical cavity. The multi-bunch electron beam has been successfully generated from a Cs2Te photocathode rf gun using a multi-pulse UV laser system. The laser optical cavity will be built like the regenerative amplification including the collision point between the electron pulse and the laser pulse to enhance the laser peak power per 1 collision on laser Compton scattering (LCS).

A table-top size soft X-ray source based on inverse Compton scattering has been developed at Waseda University. We have already succeeded in generating X-rays via inverse Compton scattering between 4.6 MeV electron beam generated from a photocathode RF-gun and 1047 nm Nd:YLF laser. The energy of the X-ray is within the !Hwater window !Iegion which can be applied to the soft X-ray microscope for biological observation. In 2007, new RF-gun cavity with Cs-Te photocathode in place of copper has been installed. The energy of electron beam has become up to 5.5 MeV due to the increase of Q-value of the gun cavity. With this achievement, generated X-ray energies will cover overall the !Hwater window !Iregion. We have been planning a multi-pulse inverse Compton scattering X-ray generation system in order to enhance a luminous intensity of the X-rays. For this purpose, we are considering a multi-pulse UV laser system for generating a multi-bunch electron beam, the method for beam loading compensation, and the multi-pulse IR laser system for the Compton collisions.

High-power extreme ultra-violet (EUV) sources are required for next generation semiconductor lithography. We start developing a compact EUV source in the spectral range of 13-14 nm, which is based on laser Compton scattering between a 7 MeV micro-bucnhed electron beam and a high intensity CO2laser pulse. The electron beam extracted from a DC photocathode gun is micro-bunched using laser modulation techinque with the Compton wavelength at a harmonic of the seeding laser [1] before the main laser Compton scattering for EUV radiation. A considerating scheme for the compact EUV source based on laser Compton scattering with micro-bunched electron beam and the anaritical study of micro-bunch generation are described in this papar. A plan of test experiment generating micro-bunched electron beam will be also introduced in this conference.

The performance of polymer electrolyte fuel cell (PEFC) is affected by an interfacial property between a proton exchange membrane (PEM) and electrodes. Thus, to develop a well-laminated membrane electrode assembly (MEA), a hybrid PEM (FN) was fabricated by mixing a radiation grafted membrane (sulfonated FEP) with ionomer (Nation (R) dispersion) which is applied to coat the interface of the PENI and electrodes.
The obtained FN, sulfonated FEP and Naflon (R) 112 were characterized in terms of water uptake, ion exchange capacity (IEC), polarization performance and electrochemical impedance. FN showed high IEC and water uptake, which would induce the highest ionic conductivity (IC) among tested PEW In terms of FN, the interface between the PEM and electrodes should have been inaproved because FN showed the lowest charge transfer resistance than other tested PEMs. The high IC and improved interface between the PEM and electrodes resulted in the best cell performance of FN in tested PEMs. (C) 2007 Elsevier B.V. All rights reserved.

A compact pico-second pulse radiolysis system has been developing at Waseda University for studying primary processes in radiation chemistry. The system is composed of a photo-injector system and a pico-second all-solid-state laser system. An infrared (IR) and an ultraviolet (UV) laser pulses are obtained from mode-locked Nd:YLF laser system and used for generation of the white light continuum as a probe light and the irradiation to the Cu cathode of a photo-cathode RF-gun, respectively. To improve signal-to-noise (S/N) ratio and time resolution of this pulse radiolysis system, we optimized both probe light and pump electron beam. As a result, our pico-second pulse radiolysis system has been enough to study the primary processes of radiation chemistry. The experimental results and the improvements of our system are described in this paper. (C) 2007 Elsevier B.V. All rights reserved.

Numerical evaluations have been performed to install a photo-cathode RF-gun into an oscillator FEL system which has been developed in Kyoto University. The original FEL system was consisted of a 4.5-cell thermionic RF gun with S-band accelerator tube of 3-m to oscillate the mid-infrared FEL. The electron beam properties have been evaluated from an RF-gun to an FEL by using PARMELA and ELEGANT. On the other hand, the FEL parameters have been calculated with GENESIS which takes the optical cavity into account. The evaluated peak current of the electron beam was 10-50 times as high as those with the thermionic RF-gun. Since the oscillator FEL requires a multi-bunch electron beam, evaluation of the round-trip development of the FEL has been also performed by a 100 bunch train beam. The results showed that the FEL gain saturation was achieved within 3 round-trips.

We have proposed a new scheme for polarized positron production, consisting of two quantum processes i.e. inverse Compton scatterings of circularly polarized laser light on high-quality electron beams and successive electron-positron pair creations. Using a circularly polarized laser beam of 532 nm scattered off a high-quality electron beam with the energy of 1.28 GeV, we have demonstrated for the first time productions of highly polarized positrons positrons with an intensity of 2x10(4) e(+)/bunch and an average energy of 36 MeV. Hence an average polarization of positrons was determined as 73 +/- 15(stat)+/- 19(syst)% by means of a newly designed positron polarimeter.

Polymer electrolyte fuel cell (PEFC) membranes based on crosslinked tetrafluoroethylene-co-hexafluoropropylene (FEP) have been fabricated by preirradiation grafting method. The chemical structures of crosslinked materials have been analyzed by Differential Scanning Calorimeter (DSC) and F-19 solid-state Nuclear Magnetic Resonance (NMR) spectroscopy. The radical yields of irradiated samples were measued by Electron Spin Resonance (ESR), and the mechanism of grafting reaction has been discussed. The styrene grafted materials were sulfonated by chlorosulfonic acid. The ion exchange capacity of the obtained sulfonated crosslinked FEP (S-FEP-X) showed 2.0 to 2.4 meq/g, which were 2.2 to 2.7 times higher than that of Nafion((R))112. Glass transition temperatures (T-g) of S-FEP-X were almost independent on crosslinking dose of FEP, and show about 96 OC, which are slightly higher than that of Nafion((R)). The electrochemical properties of the membranes have been measured, and cell performances of them have been evaluated. Ionic conductivities (ICs) of S-FEP-X are 1.2 to 1.6 times higher than that of Nafion((R)). The higher network densities gave the higher open circuit voltage (OCV). The power density of S-FEP-6ookGy was about 10% higher than that of Nafion((R)) at 500mA/cm(2). Thus, the obtained sulfonated membranes can be expected to apply for high efficiency PEFC.

Micromachining of various polytetrafluoroethylene (sintered PTFE, non-sintered PTFE and expand PTFE) using synchrotron radiation (SR) direct photo-etching has been carried out, and also the etched surface was studied by various analyses. The thin sintered (10 mu m) and expand (80 mu m) PTFE films were piled up, and the layered PTFE and non-sintered FIFE (1.2mm) irradiated by SR below the melting temperature, in order to clarify the degree of chemical and physical changes according to the depth from the etched surface. SR irradiated films were examined by F-19 solid-state magic-angle spinning (MAS) NMR spectroscopy and differential scanning calorimetric (DSC) analysis. The results showed that the modification by SR irradiation depended on the depth from the surface: within about 60 mu m from the surface, the network structure formation would be induced even in its solid state; in deeper regions, the chain scission would be dominant. Furthermore, SR was irradiated for non-sintered PTFE with different molecular conformation, compared with usual PTFE. It was found that non-sintered PTFE was also crosslinked in the surface region. Moreover, the sintered and non-sintered PTFE could be etched well. In the case of non-sintered PTFE, the distance of the non-etched remaining structures shrank by heat-treatment at 360 degrees C. The shrinking was about 20%.

Poly(tetrafluoroethylene) (PTFE) microstructure with high aspect ratio (&gt; 200) and without solid debris along the edge was fabricated with high etch rate using FIB. Evolution of PTFE by FIB is responsible for the high aspect ratio, the high etch rate, and the no solid debris. Roughness of etched surface of the PTFE increases with fluence, although edge of the etched area has good profiles. The etch mechanism seems to be complicated.

High-power extreme ultra-violet (EUV) sources are required for next generation semiconductor lithography. We start developing a compact EUV source in the spectral range of 13-14 nm, which is based on laser Compton scattering between a 7 MeV electron beam and a high intensity CO2 laser pulse. Before the main laser Compton scattering for EUV radiation, the electron beam is pre-bunched by a high power seeding laser pulse with the Compton wavelength at a harmonic of the seeding laser [1]. In this paper, we describe the preliminary consideration for the EUV source development and a plan of experiment generating micro-bunched electron beam.

A compact and high quality x-ray source is required from various fields, such as medical diagnosis, drug manufacturing and biological sciences. Laser-Compton based x-ray source that consist of a compact electron storage ring and a pulsed-laser super-cavity is one of the solutions of compact x-ray source. Pulsed-laser super-cavity has been developed for a compact high brightness x-ray sources at KEK-ATF. The pulsed-laser super-cavity increases the laser power and stably makes small laser beam size at the collision point with the electron beam. Recently, 357MHz mode-locked Nd:VAN laser pulses can be stacked stably in a 420mm long Fabry-Perot cavity with 600 enhancement in our R&D. Therefore, we have planned a compact hard x-ray source using 40MeV multi-bunch electrons and a pulse stacking technology with 42cm Fabry-Perot cavity. (LUCX Project at KEK) The photon flux is multiplied with the number of bunches by using multi-bunch beam and supercavity. Development of the super-cavity and present result of LUCX will be presented at the conference.

A photo-cathode RF gun is one of the good alternatives for the electron injector, because of its high gradient on the electron emitter causing small beam emittance, and better operationality especially for electron bunch length. Therefore, several institutes which study FEL [1], early response of a radiochemical processes [2, 3], and/or advanced accelerator technologies specially for International Linear Collider (ILC) [4] adopted the photo-cathode RF gun as their injector.
In this paper, we present a modified RF gun with new compact tuners and show results of a conditioning study using high power RF field. A starting point of this study is an design of the S-band CS2Te-cathode RF gun used in the Accelerator Test Facility of KEK (KEK-ATF).[4].

A compact X-ray source is required in various fields such as biological science and material development. At Waseda University, a table-top size soft X-ray source based on laser Compton scattering has been developed. Using 1047 nm laser beam (Nd:YLF) and 4.6 MeV electron beam generated from a photo-cathode RF-gun, we had already succeeded in generating laser Compton X-rays [1]. The energies are within the "water window" region (250-500 eV) [2] which can be applied to biological studies. For good signal to noise (S/N) ratio and more photons, we remodeled our collision chamber and laser amplifier system. With these modifications, the X-ray photons detected by a micro channel plate (MCP) have increased tenfold to reach 312/pulse. All the generated photons was estimated to be 3.28 x 10(4). Moreover, we succeeded in generating soft Xrays stably for more than 10 hours. Good SIN ratio stable X-rays have made it possible to observe the beam-laser interaction precisely.

The laser cavities of Ti:Sa and Nd: YLF laser have been designed for the multi-collision laser Compton scattering (Multi-LCS) in order to enhance the X-ray yields of the LCS hard and soft X-ray source. This cavity is like the regenerative amplification including a laser crystal and a collision point for LCS. The enhanced X-ray yield was estimated more than about I x 109 Is using the intra-cavity stored energy. In this conference, we will describe details of the laser cavity design for the Multi-LCS and future plans of the LCS X-ray sources.

Positron generation is one of the most difficult technical challenges among the ILC (International Linear Collider) subsystems. A positron source based on Laser Compton back scattering is an attractive and advanced option for the ILC positron source. Here, the positrons are generated, via the pair creation process, from high energy gamma rays which themselves are produced by Compton scattering of laser photons off a high-energy electron beam. Polarized positrons can be generated by employing a circularly polarized laser. The positron polarization is easily controlled and switched by changing the laser polarity. The electron beam can be unpolarized. The required electron energy is only a few GeV (in contrast, the "undulator scheme", another advanced option, requires at least 100 GeV or more) and the system can be prototyped and tested prior to the real construction. The laser Compton technology has many other applications like advanced X-ray sources and a good synergy is expected. In addition, this technology can be a powerful driving force for the ILC project attracting many researchers from outside the ILC community. The ILC positron source is a technical challenge and it will be realized only if the latest technologies are integrated seamlessly with the necessary R&D efforts for system specific issues. The latest technologies include high power lasers, high brightness electron beams, high finesse optical cavities for as laser-beam interaction point, etc. We present the design status and the related experimental efforts for the ILC positron source based on Laser Compton scattering. The respective advantages of various options for the electron beam (based on Linac, storage ring, and ERL) are also compared.

The radiation-crosslinked polyethersulfone (RX-PES) films were prepared by means of electron-beam irradiation under nitrogen atmosphere at 230 degrees C, where the temperature is around the glass transition temperature of PES (222 degrees C). The gel formation of RX-PES films was observed when the absorbed doses exceeded 300 kGy, which indicated the crosslinking structure formation. The G(S) of 0.10 and G(X) of 0.23 were calculated according to the Y-crosslinking mechanism. The irradiation was also performed at ambient temperature for comparison. There was no gel formation of the irradiated films even for the absorbed doses as high as 2250 kGy. The thermal properties of the original and irradiated PES films were measured by means of DSC and TGA analyses. The chemical structure of the original and the irradiated films was analyzed by means of FT-IR ATR and UV-vis spectroscopies. (c) 2006 Elsevier Ltd. All rights reserved.

Proton exchange membranes (PEMs) were prepared by pre-irradiation induced grafting of styrene (S) or styrene/divinylbenzene (S/DVB) into the radiation-crosslinked polytetrafluoroethylene (RX-PTFE) films and then sulfonated. The thicknesses of the obtained PEMs were lower than 20 mu m and the ion exchange capacity (IEC) values were around 2 meq g(-1). The surfaces of the PEMs and carbon electrodes were coated with Nafion (R) dispersion, and then membrane electrode assembles (MEAs) were prepared by hot-pressing them together. A MEA based on a Nation (R) 112 membrane was also prepared under same procedure for comparison. The performances of the MEAs in a single cell were tested under different cell temperatures and humidifications. Electrochemical impedance spectra (EIS) were measured with ac frequencies which ranged from 100 kHz to 1 Hz at a dc density of 0.5 A cm(-2). The obtained impedance curves in Nyquist representation were semicircular. (c) 2006 Elsevier B.V. All rights reserved.

Ion exchange membranes (IEMs) were prepared by preirradiation induced grafting of styrene with or without divinylbenzene (DVB) into crosslinked polytetrafluoroethylene (RX-PTFE) films and successively sulfonated by chlorosulfonic acid. The effects of the DVB concentration and solvent on the kinetic of the graft polymerization were studied. The ion exchange capacity (IEC) values of the prepared membranes ranging from 1.5 to 2.8 mequiv/g were obtained. The degree of swelling increased with the increase in the degree of grafting, while higher crosslinking density of both the RX-PTFE matrices and the grafts suppressed the degree of swelling. The chemical stabilities of the IEMs were tested by recording the weight of the membranes being soaked in hot H2O2 solutions. The weight-time curves of the prepared membranes showed one-step quick decrease due to the decomposition of the poly(styrene-sulfonic acid) (PSSA) grafts. Higher crosslinking density in both the RX-PTFE matrices and the grafts improved the chemical stability of the IEMs. The ionic conductivity of the IEMs increases with the increase in the IEC values. The IEMs with IEC values higher than 2.2 mequiv/g hold the higher ionic conductivity than that of Nafion (R) 112 membrane. (c) 2006 Wiley Periodicals, Inc.

Poly(vinyl chloride) (PVC) was decomposed by microwave (MW) irradiation (2.45 GHz) using a commercial MW oven. The efficiency of dielectric absorption was evaluated quantitatively from the rate of temperature increase on MW irradiation. The efficiency of dielectric heating increased at temperatures above the glass transition temperature (T-g). The decomposition on MW irradiation, monitored using the weight, depended on the initial (preheating) temperature of the sample before irradiation. The degradation time profile with various initial temperatures was shifted along the time axis and was successfully superimposed on a single curve. A pure PVC film was subjected to heating at a constant temperature from 230 degrees C to 310 degrees C, and the rate of weight decrease on heating was measured. The apparent activation energy was 84.4 kJ/mol for a single monomer unit. (c) 2005 Elsevier Ltd. All rights reserved.

New proton exchange membranes (PEMs) were prepared by pre-irradiation induced grafting of α-methylstyrene (AMS)/styrene (STY)/divinylbenzene (DVB) into the crosslinked polytetrafluoroethylene (RX-PTFE) films and successively sulfonated. The new PEMs showed the improved glass transition temperature and chemical stability as compared with the PEMs prepared by pre-irradiation induced grafting of STY/DVB. The balance of the cost, grafting kinetic, thermal properties and the properties of the resulted proton exchange membrane is the key point of this work. © 2005 Elsevier Ltd. All rights reserved.

We have demonstrated for the first time the production of highly polarized short-pulse positrons with a finite energy spread in accordance with a new scheme that consists of two-quantum processes, such as inverse Compton scattering and electron-positron pair creation. Using a circularly polarized laser beam of 532 nm scattered off a high-quality, 1.28 GeV electron beam, we have obtained polarized positrons with an intensity of 2x10(4) e(+)/bunch. The magnitude of positron polarization has been determined to be 73 +/- 15(stat)+/- 19(syst)% by means of a newly designed positron polarimeter.

Pulsed Laser Super-Cavity has been developed for compact high brightness x-ray sources based on Laser Compton Scattering at KEK-ATF. The Pulse Laser Super-Cavity increases the laser power and stably makes small laser beam size at the collision point with the electron beam. Recent results of Super-Cavity and multi-bunch electron beam indicate the possibility of the application to K-edge digital subtraction angiography as the compact high flux X-ray source. Therefore, we have planned a compact hard xray source using 50MeV multi-bunch electrons and a pulse stacking technology with 42cm Fabry-Perot cavity. The photon flux is multiplied with the number of bunches by using multi-bunch beam and Super-Cavity. We have finished the constraction of 50MeV linac and started operation in spring 2006. Development of the Super-Cavity and plan of compact x-ray source will be presented at the conference.

High-tech research centre project, which was started in 1999, has been approved its second phase of research in 2004 from the government. In this project, we have installed high quality electron beam system based on the RF photo-cathode at Kikui-cho campus of Waseda University. In second phase of the project, improvement of beam quality and developments of applications using the system have been improved. Beam quality has been improved by modified injection of laser beam onto the photo-cathode and obtained about 3mmmrad with the beam charge of 100 pC. Using the system, we have performed picosecond pulse radiolysis experiments for the measurements of rise signal for hydrated electron at 720nm, which is the peak band of the species. Thus, we have obtained the time resolution of the experimental system to 16ps in FWHM.

We describe a possible layout and parameters of a polarized positron source for CLIC, where the positrons are produced from polarized gamma rays created by Compton scattering of a 1.3-GeV electron beam off a YAG laser. This scheme is very energy effective using high finesse laser cavities in conjunction with an electron storage ring. We point out the differences with respect to a similar system proposed for the ILC.

High quality electron beam generation using photocathode rf-gun system and beam diagnostic techniques have been developed at Waseda University. This system can generate up to 4.6 MeV low emittance and short bunch electron beam. For bunch length monitor, rf-kicker technique is able to streak the electron bunch directly, using transverse magnetic field on the beam orbit. This technique is able to observe the longitudinal profile of the bunch and to achieve higher resolution than streak camera method.

The fabrication of polytetrafluoroethylene (PTFE) and polyimide (PI) layered films has been demonstrated by high temperature soft electron beam (soft-EB) irradiation techniques. The PTFE dispersion has been coated by wire-bar coating, equipment oil PI thin film. The PI/PTFE layered films were irradiated by EB at 330 degrees C +/- 3 degrees C in nitrogen gas atmosphere. Characterization of soft-EB irradiated PI/PTFE films have been performed by X-ray photoelectron spectroscopy (XPS). thermal analysis (DSC and TGA). and so on. According to XPS analysis on PTFE coated side. the atom ratio of F/C, H/C and N/C were 2.44, 0.04 and 0.06, respectively. Thus, it was found the fluorine coated oil PI surface. that is. PTFE molecule has been reacted with PI polymer chains by high temperature soft-EB irradiation. Moreover the obtained hybrid films showed the good adhesive properties and lower crystallinity.

Radiation-induced crosslinking of polytetrafluoroethylene [PIFE] has been established by the irradiation in its molten state under oxygen-free atmosphere. In this study, chemical crosslinking of PTFE has been demonstrated by using perfluoro-compound without any other catalyzed materials. Moreover, the characteristic properties of obtained materials have been measured by 19F NMR spectroscopy, DSC analysis and TGA. The obtained materials show the good mechanical properties and low crystallinty compared with PTFE. By DSC analysis, it is found that the obtained materials are crosslinked through thermal chemical reaction by radiacal formation through the decomposition of perfluoro-compound.

In this study, proton exchange membranes (PEMs) were fabricated by radiation-induced grafting of styrene onto FEP films and then sulfonated with chlorosulfonic acid. The hybrid PEMs were blended by Nafion and crushed sulfonated FEP fine powder. The properties of obtained PEMs were analyzed by thermal, electro-chemical measurements.

Micro structures of polytetrafluoroethylene (PTFE) and crosslinked PTFE (RX-PTFE), which has remarkable thermal stability, chemical stability and electrical insulation, have been processed by focused ion beam (FIB). Fine structures of radiation crosslinked PTFE (RX-PTFE),with the size of several tens of μm, have been fabricated by FIB maskless direct etching. PTFE and RX-PTFE with various crosslinking densities, which were controlled from 0.23 % to 1.2 %, were irradiated by 30 keV/ 2.9-12 nA Ga+ ion beam with the fluence of 0.3 × 1016 - 4.5 × 1016 ions/cm 2. It was found that the etching rate of PTFE and RX-PTFE was approximately 10-15 μm/(ion/cm2).

A low-emittance electron beam is required for the X-ray generation such as the synchrotron radiation and the laser undulator. The laser undulator based on Compton backward scattering has been developed as a compact soft X-ray source for the biological observation at Waseda University. To generate the soft X-ray pulse stably, beam diagnostics is very important. In case of the laser undulator, the energy of the electron beam can be lower than other X-ray source such as synchrotron radiation but it is difficult to measure the beam characteristics about the low energy electron beam like a 5 MeV due to the space charge effect. Consequently, the slit scan technique has been developed to measure the beam emittance precisely. In case of the photocathode rf gun, the beam emittance strongly depends on the laser injection method. To generate the low-emittance beam, the emittance comparison experiments have been performed among three deferent methods, the slanting injection (the standard injection), the slanting injection with profile shaping and the perpendicular injection using the slit scan technique. In this conference, we will report results of the experiments.

We describe a scheme for producing polarised positrons at the ILC from<br />
polarised X-rays created by Compton scattering of a few-GeV electron beam off a<br />
CO2 or YAG laser. This scheme is very energy effective using high finesse laser<br />
cavities in conjunction with an electron storage ring.

Polymer electrolyte fuel cells (PEFC) membranes based on very thin film of network polytetrafluoroethylene (PTFE)/tetrafluoroethylene-co-hexafluoropropylene (FEP) polymer-alloy (PTFE/FEP polymer-alloy: FE), have been fabricated by radiation-grafting with reactive styrene monomers using electron beam irradiation (EB) under nitrogen atmosphere at room temperature. The characteristic properties of obtained materials have been measured by ion exchange capacity (IEC), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and so on. The grafting yields showed the initial rapid increase, and then tended to saturate above 5-8 h. The grafting yields of all FE with various network densities have been achieved 80-100%. The styrene-grafted materials were sulfonated by chlorosulfonic acid. The IECs of sulfonated materials based on FE polymer-alloy have been achieved 3.0 meq/g. This suggests that IEC value is independent on network density and PTFE/FEP blend ratio. The IEC values of obtained materials are about three times higher than those of commercial perfluoro-sulfonic acid (PFSA) membranes.
By small angle X-ray scattering (SAXS), it is found that the higher network densities would give the smaller cluster sizes in sulfonated materials. Thus, the higher amount of FEP will give the smaller cluster formation of sulfonated materials. (c) 2005 Elsevier B.V. All rights reserved.

A pulse radiolysis technique is known as a powerful method to study the primary processes in radiation chemistry. However, a large-sized accelerator and a huge cost should be required for the construction and operation of pulse radiolysis system. Very recently, the new compact picosecond pulse radiolysis system composed of the small size accelerator and laser system has been developed at RISE, Waseda University. To evaluate the performance of the system, the absorption measurement of hydrated electrods was carried out as a preliminary experiment. As a result, the time resolution was estimated to be approximately 26 ps. It is analytically calculated to be approximately 30 ps (FWHM) with the convolution among the beam size, the bunch length of electron beam, the laser spot size, and the laser pulse length. The experimental value is in good agreement with the calculated one. The system has been developed to get better S/N ratio and will be applied for the study of primary processes in radiation chemistry of polymer system. (c) 2005 Elsevier B.V. All rights reserved.

High quality electron beam generation using photocathode rf gun system and its applications have been developed at Waseda University. This system can generate up to 4.6 MeV low emittance electron beam with bunch length of about 10 ps (FWHM). It is applied for soft Xray generation using laser Compton scattering and pulse radiolysis experiments based on the pump-probe technique. In the former, Compton scattering experiments between about 4.6 MeV electron beam and 1047 nm laser beam is performed at 20 degrees interaction angle, so that about 370 eV soft X-ray is generated. In the latter, the electron beam is used for the pump beam and the probe beam is generated as white light by concentrating laser beam on the water cell, so that the measurement with about 30 ps (FWHM) time resolution of the pulse radiolysis system is demonstrated for the absorption of hydrated electrons. In this conference, we will present the experimental results, status of this system and future applications.

Electron-beam technology is based on using radical reactions to destroy air pollutants. Twenty volatile organic compounds (VOCs) were irradiated with electron beams in a laboratory-scale apparatus to examine the influence of the chemical structures of the VOCs from an energetic point of view. The experiments showed that the electron-beam energy required for 90% treatment could be roughly estimated from their chemical structures. The unification of a self-shielding electron accelerator with a reactor could reduce capital costs for electron-beam systems. Electron-beam technology is a promising method for the treatment of VOCs.

An x-ray spectrometer, which consists of a multilayer device and a two-dimensional position sensitive detector, is designed for measurement of the x-ray energy spectrum and angular distribution from the nonlinear Compton scattering of 60 MeV electron and high power CO2 laser beams provided by a user facility at Brookhaven National Laboratory. A Prototype of the spectrometer has constructed and tested using isotropic 8 keV (Cu K alpha) x-rays from a seated x-ray tube.

We have been pursuing a basic study of a polarized positron source for a next generation linear collider, JLC based on two fundamental processes, i.e. inverse Compton scattering of circularly polarized laser-photons and pair-creation of a polarized gamma-ray. Polarized gamma-rays were produced at; collisions of circularly polarized laser-beams with a wave length of 532nm provided from a Nd:YAG with counter-propagating electron beams of 1.28 GeV. Since a time-duration of produced gamma-rays is extremely short, i.e. 30 ps, we have developed a transmission method in which a total flux of gamma-rays passing through magnetized iron is measured resulting in asymmetry determination. We will report technical details of a positron polarimetry, which will be soon employed to substantiate our proposed view concerning a JLC polarized positron source.

Compton scattering of laser and electron beams in a plasma channel can be utilized for high intensity X-ray source and polarized positron source for future linear colliders. Transportation of a CO2 laser beam by a 17mm plasma channel was observed. An X-ray generation experiment via laser Compton scattering in the plasma channel was attempted but the signal could not be separated from the background because of the electron beam modulation by the plasma.

The extendibility of x-ray lithography is limited by the usable proximity gap. The gap is considered to be larger than 10 mum. Practically, a line and space (L/S) pattern of 70 nm linewidth and 140 nm pitch can be formed at a 10 Am gap using a 1:1 exposure mask (1X mask). If a double-pitch mask (2 X mask), whose LIS pitch is twice as large as desired what to be printed on the wafer, is used while applying double exposures, the gap can be expanded greatly. A simulation result showed that using a 2X mask, a gap of more than 1000 mum can be used to form a L/S pattern of 200 nm pitch. An exposure test at a gap of 160 mum using the 2X mask proved sufficient to form the L/S pattern of 200 nm pitch. The principle of symmetric illumination explains this result well. The principle is also applicable to two-dimensional pattern formation, for which we propose a concept of mask design, i.e., the symmetric-illumination mask (SIM). Multidot images formed by the SIMs can produce mega- or giga-unit patterns of less than 25 nm linewidth by applying continuous writing. (C) 2003 American Vacuum Society.

We have developed a polarimetry of ultrashort pulse gamma rays based on the fact that gamma rays penetrating in the forward direction through a magnetized iron carry information on the helicity of the original gamma rays. Polarized, short-pulse gamma rays of (1.1+/-0.2)x10(6)/bunch with a time duration of 31 ps and a maximum energy of 55.9 MeV were produced via Compton scattering of a circularly polarized laser beam of 532 nm off an electron beam of 1.28 GeV. The first demonstration of asymmetry measurements of short-pulse gamma rays was conducted using longitudinally magnetized iron of 15 cm length. It is found that the gamma-ray intensity is in good agreement with the simulated value of 1.0x10(6). Varying the degree of laser polarization, the asymmetry for 100% laser polarization was derived to be (1.29+/-0.12)%, which is also consistent with the expected value of 1.3%.

Surface modification of polytetrafluoroethylene (PTFE) films by the irradiation using synchrotron radiation (SR) below the melting temperature was studied. The changes in chemical structures, surface compositions and thermal properties of the SR-irradiated PTFE were examined by solid-state F-19 NMR, X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC), respectively. In order to investigate the degree of modification as a function of depth from the irradiated surface, some PTFE thin films were stacked in layers under vacuum and then they were irradiated with SR. It was found that crosslinking reaction was induced by SR-irradiation in the solid-state within 50 mum from the exposed surface and chain scission was dominant at deeper layers. (C) 2003 Elsevier B,V. All rights reserved.

We propose a design of a polarized positron source for linear colliders. The design is based on electron-positron pair creation from polarized gamma-rays which are produced by Compton scattering of circularly polarized laser light off a high-energy electron beam. Polarized positrons are created from those gamma-rays incident on a thin conversion target. A future linear collider of the TeV-energy region requires an extraordinary large number of positrons (similar to 1 x 10(10) positrons/ bunch) in a multi-bunch time structure. To meet these requirements, our design employs a high-current, low-emittance electron beam of 5.8 GeV, 10 CO2 lasers, and 200 laser-electron collision-points. At each collision point, a pair of specially designed parabolic mirrors is installed to achieve efficient head-on collisions. This system allows us to produce high-intensity polarized gamma-rays, which effectively generate high-intensity polarized positrons with the magnitude of polarization greater than 50%. (C) 2003 Elsevier Science B.V. All rights reserved.

High-aspect ratio micro-fabrication of crosslinked polytetrafluoroethylene (PTFE) has been carried out using synchrotron radiation (SR) direct photo-etching. The etching rates of crosslinked PTFE samples with various crosslinked densities were studied by changing photon fluence of SR at different sample temperatures. The maximum etching rate of 150 micron/min was achieved at SR beam current of 600 mA. The etching rate of the sample with higher crosslinking density resulted in a higher etching rate. This rate was about two times higher than that of non-crosslinked PTFE. The effects of molecular motion and fragmentation of the molecules on etching process were discussed from temperature dependence on etching rate. Furthermore, we have found that surface modification of non-crosslinked PTFE had been proceeding during irradiation of SR to the surfaces at 140 degreesC. The modified surfaces were examined on behavior of crystallites by differential scanning calorimetry, and on chemical structure by FTIR spectroscopy and solid-state F-19 NMR spectroscopy. The results showed that properties of modified layers have dependence on depth. Crosslinking reaction would be. induced by SR irradiation even in its solid state within about 50 mum from the surface.

We have developed a. stable 7 terawatt (TW) (168 mJ per pulse, 24 fs pulse duration) Ti: sapphire laser system operating at 50 Hz for a generation of femtosecond X-ray pulses by inverse Compton scattering. We corrected the wavefront distortion of these high intensity laser pulses with adaptive optics using a Shack-Hartmann type wavefront sensor and a deformable mirror. We have also started developing a compact all-solid-state Yb: Sr-5(PO4)(3)F (Yb: S-FAP) laser system to realize a practical, X-ray pulse generation system. We measured thermal lensing induced in Yb: S-FAP crystal for design of a high-energy regenerative amplifier. In addition, we measured wavefront of the amplified pulses in the Yb: S-FAP regenerative amplifier with the wavefront sensor.

Based on the requirements from a conceptual design of a polarized positron beam for future linear colliders, we constructed a special collision system with a short focal length of 150 mm of the laser beams so as to produce γ rays through inverse Compton scattering. In order to achieve efficient laser-electron collisions, we created a special optics to produce very small e --beam sizes of σ ex0 = 7.6 μm and σ ey0 = 5.4 μm in the horizontal and vertical directions at the collision point. Using laser light with a wavelength of 532 nm and an e - beam of 1.28 GeV provided from the ATF-damping ring at KEK, we generated 2 × 10 5 γ rays with a time duration of 26 ps in rms, leading to a peak brightness of 1.7 × 10 18/(mrad 2mm 20.1%bandwidth s) near to the maximum energy of 56 MeV. © 2003 The American Physical Society.

A technique of laser-pulse shaping was developed for low-emittance electron-beam generation in a photocathode radio-frequency (rf) gun. The emittance growth due to space charge and rf effects in the rf gun was experimentally investigated with square and gaussian temporal pulse shapes. It was found that the square pulse shaping was a useful tool for both the reduction of nonlinear space-charge force and the correction of linear space charge. The normalized transverse rms emittance at 1 nC was obtained to be 1.20 pimm-mrad for the square pulse shape with pulse length of 9 ps full width at half maximum. The emittance was measured as a function of the electron bunch charge and the laser-pulse length. (C) 2002 American Institute of Physics.

Two mode-locked Ti:sapphire lasers of different wavelengths were precisely synchronized by a simple feedback system employing sum-frequency generation (cross correlation). When the timing error exceeded the pulse duration, the periodic bunch of the sum-frequency pulse was used for rough timing adjustment. Using cross correlation with a stretched pulse, we struck a balance between wide locking range and sensitive timing detection. When the two lasers were well-synchronized, we obtained a continuous cross-correlation pulse train for 3 min. The holding time of the laser synchronization was extended to over one hour by adding a motorized stage to the PZT-mounted cavity mirror. We estimated the rms timing jitter between the two lasers by a scanning cross-correlation measurement. We confirmed that the rms timing jitter of the two lasers during 1.8 s was 28 fs.

On the basis of velocity modulation, we have developed a positron-beam buncher for the measurement of ortho-positronium lifetimer tau(o)-p(s) and TOF. Since high permeability cores were used, the buncher was constructed compactly and was used to efficiently produce a bunched beam with a bunch width of 2.2 ns (FWHM) and a repetition period of 960 ns. We have measured the lifetime of ortho-positronium using the buncher and obtained tau(o)-p(s) = 127 ns. In this paper, we report on the technical details and performance of the buncher. (C) 2002 Elsevier Science B.V. All rights reserved.

We demonstrated generation of square-shaped ultraviolet pulses and that they reduces the emittance of electron beams from laser-photocathode RF-gun. Some frequency components of femtosecond pulses from a Ti:sapphire oscillator are modulated with a pulse shaper that consists of a lens pair, gratings, and a liquid crystal spatial light modulator (LC-SLM) to generate square-shaped pulses. The shaped pulses were amplified up to 3 mJ through a regenerative amplifier, and were converted to ultraviolet region with two different nonlinear crystals. Energy of the shaped pulses was about 100 muJ which is sufficient to generate electron charge of 1 nC. In our experiment, emittance of electron beam was reduced to as low as almost the half of that with non-shaped pulses.

The generation of amplified picosecond square shaped pulses in ultraviolet region for an RF photocathode was described. The spectral phase reconstructed from the experimental interferogram of the shaped pulse and the unshaped pulse was measured as a function of spatial solution. It was shown that the emittance of the electron beam by using square shaped pulse was two times lower than the value by using a gaussian shaped pulse.

High aspect-ratio (more than 10) microfabrication of crosslinked polytetrafluoroethylene (PTFE) has been carried out using synchrotron radiation (SR) direct photo-etching, The etching rates of crosslinked PTFE samples with various crosslinked densities were studied by changing photon fluence of SR at different sample temperatures, The etching rate of the sample with W-her crosslinking density resulted in a higher etching rate. This rate was about two times higher than that of normal PTFE. The temperature dependence of the etching rates indicated that molecular motion of alpha-relaxation of samples and structures of smaller fragments (i.e., etched products) produced by irradiation of SR with high dose rate play an important role for SR direct photo-etching. Moreover, we have found that surface modification of PTFE had been proceeding during irradiation of SR to the PTFE at 140 degreesC. The results of differential scanning calorimeter measurements for the modified layers showed that the layers might have crosslinking character. (C) 2002 Elsevier Science B.V. All rights reserved.

Micromachining of crosslinked PTFE (polytetrafluoroethylene) using synchrotron radiation direct photo-etching method has been demonstrated. High aspect-ratio microfabrication was carried out. The etching rate of crosslinked PTFE was higher than that of non-crosslinked PTFE. Through the etching rate measurements of various samples, it was found that synchrotron radiation etching rate of crosslinked PTFE only depends on the degree of crosslinking, neither molecular weight nor crystallinity. The effect of molecular motion on etching process was discussed from temperature dependence data on etching rate. Furthermore, the surface region of synchrotron radiation irradiated sample was investigated by Fourier transform infrared spectroscopy and the experimental result showed that the modification induced by synchrotron radiation proceeded before desorption.

The low emittance and short pulse electron beam is expected to be used in a wide field, such as X-ray generation by inverse Compton scattering, pulse radiolysis, etc. The laser driven photo cathode rf gun system is possible to produce the low emittance and short pulse electron beam. It is very important for generating the low emittance and short pulse electron beam to measure the beam characteristics such as the bunch length precisely. In this report, the measurement system of the bunch length using frequency analysis for the photoelectron beam generated by the rf gun and results of the preliminary experiment at KEK-ATF (Accelerator Test Facility) injector linac is described.

We have conducted the research project named &quot;High-Tech Research Center Project&quot; at Waseda University, which is supported by the Ministry of Education, Culture, Sports, Science and Technology. In this project, a laser photo-cathode rf-gun with 1.6 acceleration cells with Mg cathode has been installed for production of low emittance and short bunched electron beam. Main parts of rf source for the rf-gun consists of 10 MW s-band klystron and a small pulse modulator. The pulse modulator has good stability and flatness of the output pulse. The amplitude jitter of klystron voltage was realized down to 0.38 % (p-p) for 20000 pulses and the pulse flatness down to 0.25 % (within &gt;1.5 μs pulse flat-top). High quality electron beam is very powerful tool for the study on radiation physics, radiation chemistry, material science, etc. Development of short X-ray pulse generation by the inverse Compton scattering between high quality electron beam and laser light, will be started in 2001 fiscal year. The system will be applied to the pulse radiolysis experiments for the studies on radiation physics and chemistry.

An 1.6 cell rf-gun system has been installed at Waseda University for the generation of high charge, short pulse and low emittance electron beam. The gun is one of essential component for X-ray generation using inverse Compton scattering between photo electron bunch and laser pulse. An all-solid-state picosecond Nd:YLF laser system has been installed at Waseda University and will be used not only for photo electron generation in the rf-gun but also for collision with the photo electron bunch. The laser system has the frequency conversion section, which is operated to produce the UV (262 nm) using BBO crystals from the amplified fundamental (1047 nm). Extremely stable laser system is required for the generation of high quality electron beam, and the system is essential component for the generation of X-rays through the inverse Compton scattering. Timing and intensity stabilities of laser pulse have been measured using time domain demodulation technique. As the results, timing stability of 0.26 ps against to the local oscillator of rf and intensity stability of 0.11% have been achieved. We have carried out the numerical simulation to calculate the number of photons and the energies of X-rays by changing the crossing angles.

© 2001 Japan Soc. Of Applied Physics. Summary form only given. Difficulties in X-ray lithography are now condensed into mask related matters. Since the exposure mode is basically 1:1, more strict accuracy is requested for mask fabrication than for the final images. Mask fabrication technology has made remarkable progress, and image formation of 70 nm line width was reported recently (Miyatake et al, 2001). Meanwhile, pattern reduction necessitates narrowing gaps between mask and wafer, since the gaps decrease in proportion to the square of the line width. If we want to form 25-35 nm two-dimensional patterns in future, mask-wafer gaps of 2-4 μm are needed; it is impractical. Therefore, around 50-70 nm image forming has been considered as the limits of X-ray lithography. Recently, three types of X-ray mask were proposed which enable 25-35 nm image formation while keeping a practical proximity gap &gt;8 μm. The first is enlarged pattern masks (EPMs), applying a line-narrowing effect by edge diffraction. The second is interference slit masks (ISMs), which form design images by interference effect from the slits of the mask. The third is focusing x-ray masks (FXMs), which form an array of concave lenses using the absorbing materials on the mask membrane. These masks, which reduce mask patterns partially (PRMs: partially reducing masks), relieve the limitation of the proximity gaps. In this article, we discuss the design of the masks, beamlines and procedures of writing for 25 nm image formations.

A novel phase-locked loop was developed for synchronization between two mode-locked lasers. The up-converted signal was used to detect phase difference. The relative timing jitter was reduced to less than 500 fs for 30 minutes.

In-situ feedback controlled pulse shaping has demonstrated when a pulse shaping apparatus is placed before the amplifier. For the efficient and rapid control, we evaluated optimization algorithms and parameters.

We precisely measured submili-joule and arbitrarily shaped femtosecond pulses with phase-only filters by crosscorrelation and spectral interferogram scheme. The femtosecond pulse shaping apparatus was placed between air oscillator and a regenerative amplifier.

Arbitrary shaping of a sub-milli joule femtosecond pulses has been demonstrated by manipulation of optical frequency phase components on the Fourier plane. The shaped pulses were pulse trains and picosecond square pulses for low emittance electron generation in a RF photocathode. Since the pulse shaping apparatus was placed between an oscillator and a pulse stretcher in order to avoid damage to the liquid crystal spatial light modulator, phase-only modulation was used for shaping to avoid damage to optical elements in a regenerative amplifier. The phase modulation was designed by simulated annealing optimization method.

We performed an experiment of high brightness gamma(gamma)-rays production through laser-electron(e(-)) collisions using an insertion device with a short focal length of laser optics. Number of generated gamma-rays with the bunch length of 26 psec (r.m.s) was 0.92 x 10(5)/bunch, thus leading to brightness 2.5 x 10(17)/(mm(2) . mrad(2) . 0.1% band-width . sec). Quantitative considerations on the basis of numerical model permitted to elucidate how characteristics of e(-) and laser beam influence collision mechanisms.

7.6 × 106 x-ray photons per 3.5 ps pulse are detected within a 1.8-2.3 Å spectral window during a proof-of-principle laser synchrotron source experiment. A 600 MW CO2 laser interacted in a head-on collision with a 60 MeV, 140 A, 3.5 ps electron beam. Both beams were focused to a σ = 32 μm spot. Our next plan is to demonstrate 10 10 x-ray photons per pulse using a CO2 laser of ∼1 TW peak power. © 2000 The American Physical Society.

A comprehensive description of a polarized positron project is presented in terms of physics motivations for utilizing a polarized positron in electron-positron collider experiments, a proof-of-principle experiment and a conceptual design of a polarized positron source for the future linear collider JLC, In order to verify a proposed method of creating highly polarized positron beams via successive two fundamental processes, i.e, Compton scattering and pair creation, we have been performing basic experiments both at KEE; and BNL. First observation of positrons was made at KEK using an electron beam of 1.26 GeV and a laser of 2.33 eV. High-intensity picosecond X-rays were also generated at BNL using a specially designed Compton chamber. In order to realize polarized positron beams of the JLC which have considerably high intensity, i.e, 0.7 x 10(10) e(+)/pulse and a complicated multi-bunch structure, we have achieved a possible scheme for the Compton scattering system and a positron capture section into an L-band linac. (C) 2000 Elsevier Science B.V. All rights reserved.

We have proposed a new method of generating highly polarized positrons through Compton scattering of polarized laser lights off relativistic electron beams and successive pair creation. To realize high-luminosity laser-electron collisions, we constructed a specially designed chamber which equips off-axis parabolic mirrors with a through hole at the center, This mirror achieves strong focusing of laser lights as well as head-on collisions of laser lights with e(-) beams, so that the luminosity can be significantly increased. A polarimeter is designed for the measurement of positron polarization. (C) 2000 Elsevier Science B.V. All rights reserved.

Arbitrarily shaped femtosecond laser pulses can be obtained using amplitude-phase filters or a phase-only filter. The results with a phase-only filter, which does not cause damages in a process of the chirped pulse amplification, were presented. The system consisted of a mode-locked Ti:sapphire laser oscillator, a pulse shaping apparatus, a pulse stretcher, a regenerative amplifier and a pulse compressor. Phase-only filters were designed by simulated annealing optimization method for the targeted profiles.

Femtosecond pulses were shaped to square shaped picosecond pulses with a phase-only filter. The system used consists of a mode-locked Ti:sapphire laser oscillator, a pulse shaping apparatus, a pulse stretcher, a regenerative amplifier and a pulse compressor. Although the amplifier caused some phase distortion, the experimental results are in good agreement with numerical simulations. © 2000 IEEE.

The performance tests were done for a 1.6 cell s-band BNL-type photocathode RF electron gun, GUN-IV, under a condition of 1.5 MW RF power input and 266 nm Nd:YAG laser pulse irradiation. As a result, the maximum energy and the maximum charge/bunch were obtained as 1.6 MeV and 120 pC/bunch, respectively. In addition, a sinusoidal behavior of current with the polarization angle of laser light were measured. Furthermore, the change in current as a function of laser injection phase was measured and reasonably reproduced by a numerical calculation.

Low emittance sub-picosecond electron pulses are expected to be used in a wide field, such as free electron laser, laser acceleration, femtosecond X-ray generation by inverse Compton scattering, and pulse radiolysis, etc. In order to produce the low emittance sub-picosecond electron pulses, we are developing a compact racetrack microtron (RTM) with a new 5 MeV injection system adopting an laser photo cathode RF gun. The operation of RTM is kept under the steady state of beam loading for long pulse mode so far. We have investigated for the first time by numerical simulation in the case of short- and single-pulse acceleration. As the results, RTM is also useful to accelerate a picosecond electron pulse under a transient state of beam loading. In the simulation, a picosecond electron pulse is accelerated to 139 MeV in RTM for the injection of about 5 MeV pulse with pulse length of 3 picoseconds, charge of 1 nC per pulse, and emittance of 1.8 πmm mrad, which corresponds of output of the RF gun.

Laser-Compton scattering with picosecond CO2 laser pulses is proposed for generation of high-brightness x-rays. The interaction chamber has been developed and the experiment is scheduled for the generation of the x-rays of 4.7 keV, 107 photons in 10-ps pulse width using 50-MeV, 0.5-nC relativistic electron bunches and 6 GW CO2 laser.

We observed positron (e(+)) production for the first time on the basis of the new idea that gamma-rays produded via Compton scattering of laser lights off electron (e(-)) beams of 1.26 GeV/c provided by the ATF damping ring can create pairs of e(+) and e(-). It is verified that the production rates of e(+/-) and gamma-rays are consistent with each other as well as in good agreement with theoretical predictions. We also attain a conceptual design of a polarized e(+) source for the future linear collide JLC which requires high intesity e(+) beams with a complicated time structure of multi-bunching.

Laser-Compton scattering can generate X-rays or y-rays with high brightness by applying highpeak- power laser pulses to relativistic electron bunches. We have proposed laser-Compton scattering to generate polarized y -rays which can induce pair-creation to produce polarized positrons for JLC (Japan Linear Collider) project[ 11. As a photon source of the Compton scattering, a picosecond CO2 laser system is going to be applied for our experiment because of the higher scattering cross section than near-infiared solid-state lasers, laser power scalability, the laser efficiency and the possibility of high-repetition rated operation. Not only for the JLC positrons source, Compton scattering with Ca-laser has a possibility to be a compact high intensity X-ray source as an alternative of synchrotron radiation source[2]. We have been developing a laser-Compton scattering chamber for a preliminary experiment, in which COz laser pulses and electron bunches propagate along the same axis in opposite direction and collide at the focal point. Fig. 1 is the sketch of the Compton chamber to be applied in the beamline of the Accelerator-Test-Facility in Brookhaven National Laboratory. Picosecond CO2 laser beams are introduced &amp
om the side window and focused by an off-axis parabolic Cu mirror of 50 mm diameter with the focal length of 15 cm. Cu mirror has 5 mm diameter hole along the electron beam axis to have electrons pass through. An axicon telescope system made of ZnSe is placed on the CO2 beam axis just before the Compton chamber in order to modify spatial profiles as shown in Fig. 2-(a) to accommodate to the mirror with holes. Fig. 2-(b) represents a numerically calculated CO2 beam profile at the focal point. The estimated beam waist size is about 100 pm, which is almost same as the electron beam size at the colliding point. After the focal point, the diverging laser beams are paralleled by another Cu mirror and extracted fiom the chamber.

Sub-picosecond electron pulses are desirable for generating femtosecond X-ray pulses. By numerical simulation, it has become clear that racetrack microtron (RTM) has unique features to produce very short electron bunches by itself. In addition, it has proved experimentally that RTM has beneficial characteristics to accelerate only an excellent quality beam in both emittance and energy spread. The measured and calculated results of such distinctives are shown in this paper.