Grant-in-Aid for Scientific Research (A)
|Allocation Type||Single-year Grants |
Particle/Nuclear/Cosmic ray/Astro physics
|Research Institution||Nagoya University |
NAKANISHI Tsutomu Nagoya University, Department of Physics, Graduate school of Science, Professor (40022735)
YAMAMOTO Masahiro Nagoya University, Department of Physics, Graduate school of Science, Assistant Professor (00377962)
KOBAYAKAWA Hisashi Nagoya University, Department of Material Science, graduate school of Engineering, Professor (emeritus) (50022611)
HORINAKA Hiromichi Osaka Prefecture University, Department of Physics and Electronics, Faculty of Engineering, Professor (60137239)
KURIKI Masao Hiroshima University, Graduate School of Advanced Science of Matter, Associate Professor (80321537)
竹田 美和 名古屋大学, 大学院・工学研究科, 教授 (20111932)
宇治原 徹 名古屋大学, 大学院工学研究科, 助教授 (60312641)
高嶋 圭史 名古屋大学, 大学院・工学研究科, 助手 (40303664)
|Project Period (FY)
2003 – 2005
Completed (Fiscal Year 2005)
|Budget Amount *help
¥51,090,000 (Direct Cost: ¥39,300,000、Indirect Cost: ¥11,790,000)
Fiscal Year 2005: ¥9,750,000 (Direct Cost: ¥7,500,000、Indirect Cost: ¥2,250,000)
Fiscal Year 2004: ¥13,520,000 (Direct Cost: ¥10,400,000、Indirect Cost: ¥3,120,000)
Fiscal Year 2003: ¥27,820,000 (Direct Cost: ¥21,400,000、Indirect Cost: ¥6,420,000)
|Keywords||Emittance / Electron source / Linear collider / ERL accelerator / Spin polarization / Negative Electron Affinity (NEA) / Field emission dark current / Extremely high vacuum technology / ビームエミッタンス / 低エミッタンス電子源 / 偏極電子源 / NEA-GaAsフォトカソード / tip状-GaAsフォトカソード / 電子・陽電子リニアコライダー / ERL(Energy Recovery Linac) / 低エミッタンス / 負の電子親和性(NEA)表面 / 200keV直流型電子銃 / 超高真空環境 / 電極間暗電流 / Pepper-Pot法 / 正の電子親和性(PEA) / 電界放出型偏極電子源 / GaAs / ピコ秒レーザー / 超高真空 / フォトカソード|
A 200-keV spin polarized electron source system for the electron-positron linear collider has been developed and completed. It employs a combination of two physical mechanism; optical polarization process and NEA (Negative Electron Affinity) surface emission mechanism for polarized conduction electrons. This type of electron source has the advantages to produce not only the polarized electrons, but also the high current density beam and the low emittance beam.
Following performances are obtained by using this 200-keV electron gun
(1) An extremely high vacuum of 2?~10^<-9>-Pa is obtained around the photocathode (PC), and the dark-lifetime of NEA surface is extended for more than 300-hours.
(2) The low dark current electrode is fabricated by using the Mo material for a cathode and the Ti material for an anode. At a bias voltage of 200-kV, the dark current is less than 1-nA, and the stable operation of more than 500-hours is achieved.
(3) As the polarized electron source, the world highest field gradient of 3.0-MV/m is achieved.
(4) The spin polarization of 92-% and the quantum efficiency of 0.5-% are achieved by using the GaAs-GaAsP strained superlattice photocathode.
(5) High current density 200-kV beam; 8-nC/bunch (1.6-ns bunch-width) that is 5-A peak-current, can be produced.
(6) The constant average current of 50-??A can be extracted for more than 120-hours form the same NEA surface.
(7) The thermal emittance for the electron beam emitted from the NEA surface of both of bulk-GaAs and superlattice photocathode are measured by using a pepper-pot method.
(8) As the results, the same emittance value of 0.1 ??mm?Emrad is observed for the both photocathode for the band-gap excitation, but the emittance-growth due to the higher laser energy excitation is smaller for the superlattice than that of the bulk-GaAs photocathode.