2001 Fiscal Year Final Research Report Summary
Polarized Electron Beam with Sub-nanosecond Mulch-bunch Structure
| Project/Area Number |
10354003
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Graduate School of Science, Nagoya University |
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Principal Investigator |
NAKANISHI Tutomu Nagoya Univ., Graduate School of Science, Professor, 大学院・理学研究科, 教授 (40022735)
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| Co-Investigator(Kenkyū-buntansha) |
HORINAKA Hiromichi Osaka Prefecture Univ., College of Engineering, Professor, 工学部, 教授 (60137239)
YOSHIOKA Masakazu KEK, Accelerator Laboratory, Professor, 加速器研究施設, 教授 (50107463)
KOBAYAKAWA Hisashi Nagoya Univ., Graduate School of Engineer, Professor, 大学院・工学研究科, 教授 (50022611)
BABA Simio NEC, Fundamental Research Laboratory, Research Director, 研究部長
SAKA Takashi Daido Institute of Technology, Dept. of Engineering, Professor, 工学部, 教授
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| Project Period (FY) |
1998 – 2000
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| Keywords | Spin / Polarization / Polarized Electron Source / Superlattice Semiconductor / Laser / Photocathode / Mulch-hunch Beam / Linear Collider |
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| Research Abstract |
We developed polarized-electron-sources to produce an intense beam with a multi-bunch structure (2x10^<10>electrons/bunch, 100bunches, 2.8ns separation) for future linear colliders, such as Japan Linear Collider (JLC).
1 ) Polarized Electron Beam with Sub-ns Multi-bunch Structure
The NBA (Negative-Electron-Affinity) surface is indispensable to allow polarized electrons inside GaAs to emit into vacuum. However, it brings the serious problem due to photo-voltage effect that occurs when high-density electrons are excited by the first-laser-bunch and accumulated in NBA surface. Then the band-bending of GaAs surface is declined and then the electron emission by the second-laser bunch is strongly suppressed. We could find that the photo-voltage effect can be relaxed using the photocathode with a superlattice structure instead of the strained GaAs, and could demonstrate the clean double-bunch beam can be produced by GaAs-GaAsP or InGaAs-AlGaAs photocathode. The important problem is solved to produce the polarized multi-bunch beam for JLC by this work.
2 ) Development High-Gradient Polarized Gun
The next important subject is to produce the low emittance (【less than or equal】10πmm -mrad) beam by developing a gun with highergradient field (【greater than or equal】1MV/m) at GaAs surface. We constructed a new gun and succeeded to apply 200kV to electrodes with a small dark current (【less than or equal】1nA), which is much higher than 120kV achieved by SLAC-gun. We could obtain the high quantum efficiency by cleaning the GaAs surface by atomic hydrogen. We also pursued to produce a low emittance beam by an RF-gun. The two-photon-excitation method was proposed by us to solve a serious problem of survivability of NBA surface under high gradient field of 100MV/m. We could already confirm that the high polarization of 90% can be obtained by this method.
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[Publications] C.Suzuki, T.Nakanishi, S.Okumi, T.Gotou, K.Togawa, F.Furuta, K.Wada, T.Nishitani, M.Yamamoto, J.Watanabe, S.Kurahashi, K.Asano, H.Matsumoto, M.Yoshioka, H.Kobayakawa: "Fabrication of Ultra-clean Copper Surface to Minimize Field Emission Dark Currents"Nuclear Instrument & Methods in Physics Research. A462. 337-348 (2001)
Description
「研究成果報告書概要(和文)」より
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[Publications] K.Togawa, T.Nakanishi, T.Baba, F.Furuta, H.Horinaka, T.Kato, Y.Kurihara, H.Matsumoto, T.Matsuyama, T.Nishitani, S.Okumi, T.Omori, T.Saka, C.Suzuki, Y.Takeuchi, K.Wada, K.Wada, M.Yamamoto, M.Yoshioka: "Production of polarized electron beam with sub-nanosecond multi-bunch structure from superlattice photocathode"Nuclear Instrument & Methods in Physics Research. A455. 118-122 (2000)
Description
「研究成果報告書概要(和文)」より
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[Publications] K.Togawa, T.Nakanishi, T.Baba, F.Furuta, H.Horinaka, T.Ida, Y.Kurihara, H.Matsumoto, T.Matsuyama, M.Mizuta, S.Okumi, T.Omori, C.Suzuki, Y.Takeuchi, K.Wada, K.Wada, M.Yoshioka: "Surface Charge Limit in NEA Superlattice Photocathodes of Polarized Electron Source"Nuclear Instrument & Methods in Physics Research. A414. 431-445 (1998)
Description
「研究成果報告書概要(和文)」より
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[Publications] S.Nakamura, W.v.Drachenfels, D.Durek, F.Frommberger, M.Hoffmann, D.Husmann, B.Kiel, F.Klein, F.J.Klein, D.Menze, T.Michel, T.Nakanishi, J.Naumann, S.Okumi, T.Reichelt, H.Sato, B.Schoch, C.Steier, K.Togawa, T.Toyama, S.Voigt, M.Westermann: "Spin Relaxation of Electrons in Graded Doping Strained GaAs-Layer Photocathode of Polarized Electron Source"Nuclear Instrument & Methods in Physics Research. A411. 93-105 (1998)
Description
「研究成果報告書概要(和文)」より
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[Publications] C. Suzuki, T. Nakanishi, S. Okumi, T. Gotou, K. Togawa, F. Furuta, K. Wada, T. Nishitani, M. Yamamoto, J. Watanabe, S. Kurahashi, K. Asano, H. Matsumoto, M. Yoshioka and H. Kobayakawa: "Fabrication of Ultra-clean Copper Surface to Minimize Field Emission Dark Currents"Nuclear Instrument & Methods in Physics Research. A462. 337-348 (2001)
Description
「研究成果報告書概要(欧文)」より
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[Publications] K. Togawa, T. Nakanishi, T. Baba, F. Furuta, H. Horinaka, T. Kato, Y. Kurihara, H. Matsumoto.T. Matsuyama, T. Nishitani, S. Okumi, T. Omori, T. Saka, C. Suzuki, Y. Takeuchi, K. Wada, K. Wada, M. Yamamoto and M. Yoshioka: "Production of polarized electron beam with sub-nanosecond multi-bunch structure from superlattice photocathode"Nuclear Instrument & Methods in Physics Research. A455. 118-122 (2000)
Description
「研究成果報告書概要(欧文)」より
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[Publications] K. Togawa, T. Nakanishi, T. Baba, F. Furuta, H. Horinaka, T. Ida, Y. Kurihara, H. Matsumoto, T. Matsuyama, M. Mizuta, S. Okumi, T. Omori, C. Suzuki, Y. Takeuchi, K. Wada, K. Wada and M. Yoshioka: "Surface Charge Limit in NEA Superlattice Photocathodes of Polarized Electron Source"Nuclear Instrument & Methods in Physics Research. A414. 431-445 (1998)
Description
「研究成果報告書概要(欧文)」より
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[Publications] S. Nakamura, W. v. Drachenfels, D. DurekJ5. Frommberger, M. Hoffmann, D. Husmann, B. Kiel, F. Klein, F. J. Klein, D. Menze, T. Michel, T. Nakanishi, J. Naumann, S. Okumi, T. Reichelt, H. Sato, B. Schoch^C. Steier, K. Togawa, T. Toyama, S. Voigt and M. Westermann: "Spin Relaxation of Electrons in Graded Doping Strained GaAs-Layer Photocathode of Polarized Electron Source"Nuclear Instrument & Methods in Physics Research. A411. 93-105 (1998)
Description
「研究成果報告書概要(欧文)」より
