1997 Fiscal Year Final Research Report Summary
The New Generation of Spin Polarized Electron Sources
| Project/Area Number |
07504001
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 展開研究 |
|---|
| Research Field |
素粒子・核・宇宙線
|
|---|
| Research Institution | Nagoya University |
|---|
Principal Investigator |
NAKANISHI Tsutomu Nagoya University, Graduate School of Science Professor, 大学院・理学研究科, 教授 (40022735)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KATO Toshihiro Daido Steel Co., Research&Development Lab.Chief of Research Section, 新素材研究所, 主任研究員
BABA Toshio NEC,Fundamental Research Laboratory Chief of Research Section, 基礎研究所, 研究部長
SAKA Takashi Daido Institute of Technology Professor, 工学部, 教授
HORINAKA Hiromichi University of Osaka Prefecture, College of Engineering Professor, 工学部, 教授 (60137239)
YOSHIOKA Masakazu KEK-High Energy Accelerator Research Organization Professor, 高エネルギー加速器研究機構, 教授 (50107463)
|
|---|
| Project Period (FY) |
1995 – 1997
|
| Keywords | Spin / Polarization / Polarized Electron Source / Quantum efficiency / Photocathode / Superlattice / Field emission dark current / Electron gun |
|---|
| Research Abstract |
1)ConstructIon of 70 keV polarized electron gun The polarized gun for high energy accelerators was completed and has become into operation. The most serious problem was the degradation of NEA (Negative Electron Affinity) surface due to the poison gases (H20, Co2 etc.) produced by the field emission dark currents between the HV electrodes.The technology to fabricate the clean and mirror-flat surface of the stainless-steel electrode was developed and the dark current was supressed below 10 nA level under 100 kV application. As a result, the stable beam with the polarization more than 80 % and the peak current of 1.6 A can be produced by this gun.
2)Overcome of "Surface Charge Limit" phenomenon by superlattice photocathodes The maximum current, extracted from an NBA cathode, is limited by so-called Surface Charge Limit (SCL), rather than by the space charge limit, as the conduction electrons are trapped in the band-bending region of NBA surface. It was first demonstrated by us that the SCL phenomena is overcome by using the superlattice structure photocathodes developed by us. In fact, the high density beam with a multi-bunch structure could be produced from the superlattice photo cathode and this result gave the promising perspective for aplication to future linear colliders.
3)Developments of new material photo cathodes with superlattice structure In addition of GaAs-A1GaAs, InGaAs-GaAs and InGaAs-AIGaAs superlattice structures, the new combination of materials, GaAs-GaAsP superlattice was developted. We expected that this combination gives higher quantum efficiency and higher plarization, since it has the smaller band-offset for conduction-band, while the larger one for valence-band. As expected, the first sample gave the promising result with the polarization higher than 80 % and the quantum efficiency larger than 0.3% at laser wave-length of 803nm. Further optimizations of structure parameters are in progress to achieve the higher performances.
|
-
-
-
-
-
-
-
-
-
[Publications] M.Tawada, T.Baba, Y.Kurihara, M.Mizuta, T.Nakanishi, K.Nishitani, S.Okumi, T.Omori, C.Suzuki, Y.Takeuchi, K.Togawa andM.Yoshioka: "Quantum-efficiency Dependence of the Spin Polarization of Photoemission from a GaAs-AlGaAs Superlattice" Jpn.J.Appl.Phys.36. 2863-2864 (1997)
Description
「研究成果報告書概要(欧文)」より
-
[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 and M.Westermann: "Acceleration of Polarized Electrons in ELSA" Nucl.Instr.and Meth.in Phys.Res.A411. 93-105 (1998)
Description
「研究成果報告書概要(欧文)」より
-
[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" Nucl.Instr.and Meth.in Phys.Res.A414. 431-445 (1998)
Description
「研究成果報告書概要(欧文)」より
-
-
