中国物理B ›› 2007, Vol. 16 ›› Issue (1): 51-57.doi: 10.1088/1009-1963/16/1/009

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Passive magnetic shielded spin polarized electron source with optical electron polarimeter

丁海兵, 庞文宁, 刘义保, 尚仁成   

  1. Department of Physics, Tsinghua University, Beijing 100084, China
  • 收稿日期:2006-11-17 修回日期:2006-08-22 出版日期:2007-02-01 发布日期:2007-02-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 10134010).

Passive magnetic shielded spin polarized electron source with optical electron polarimeter

Ding Hai-Bing(丁海兵), Pang Wen-Ning(庞文宁), Liu Yi-Bao(刘义保), and Shang Ren-Cheng(尚仁成)†   

  1. Department of Physics, Tsinghua University, Beijing 100084, China
  • Received:2006-11-17 Revised:2006-08-22 Online:2007-02-01 Published:2007-02-01
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 10134010).

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摘要： A new GaAs(100) spin polarized electron source with an optical polarimeter, which is employed in the field of polarized electron and gas atom collision, is presented in detail. The apparatus is passive-magnetic-shielded by a box and a cylinder made of nickel--iron--molybdenum soft magnetic alloy without Helmholtz coil arrangement. And a uniformly distributed residual magnetic field of less than 5×10-7,T is obtained near the collision area. The spin polarized electron beam is transmitted and focused onto collision point from photocathode by a set of electron optics with more than 25% transmission 95cm distance through an 1mm diameter aperture. Construction and operation of the apparatus, such as vacuum and magnetic shielding system, photocathode, laser optics, electron optics and polarimeter are discussed. The polarization of the spin polarized electron beam is determined to be 30.8\pm3.5% measured with a He optical polarimeter.

关键词: spin polarized electron source, optical electron polarimeter, polarization

Abstract: A new GaAs(100) spin polarized electron source with an optical polarimeter, which is employed in the field of polarized electron and gas atom collision, is presented in detail. The apparatus is passive-magnetic-shielded by a box and a cylinder made of nickel--iron--molybdenum soft magnetic alloy without Helmholtz coil arrangement. And a uniformly distributed residual magnetic field of less than 5×10-7 T is obtained near the collision area. The spin polarized electron beam is transmitted and focused onto collision point from photocathode by a set of electron optics with more than 25% transmission 95cm distance through an 1mm diameter aperture. Construction and operation of the apparatus, such as vacuum and magnetic shielding system, photocathode, laser optics, electron optics and polarimeter are discussed. The polarization of the spin polarized electron beam is determined to be 30.8$\pm$3.5% measured with a He optical polarimeter.

Key words: spin polarized electron source, optical electron polarimeter, polarization

中图分类号:  (Charged-particle beam sources and detectors)

  • 07.77.Ka
07.55.Nk (Magnetic shielding in instruments) 07.60.Fs (Polarimeters and ellipsometers) 41.85.Ja (Particle beam transport) 85.60.Ha (Photomultipliers; phototubes and photocathodes)