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Brightness enhancement of a linac-based intense positron beam for total-reflection high-energy positron diffraction (TRHEPD)

  • Masaki Maekawa
  • Ken Wada
  • Yuki Fukaya
  • Atsuo Kawasuso
  • Izumi Mochizuki
  • Tetsuo Shidara
  • Toshio Hyodo
Regular Article
Part of the following topical collections:
  1. Topical issue: Electron and Positron Induced Processes

Abstract

The brightness of a linac-based intense positron beam was enhanced for total-reflection high-energy positron diffraction (TRHEPD) measurements. The beam initially guided by a magnetic field was released into a non-magnetic region and followed by a transmission-type remoderation. The term “TRHEPD” is a new name of reflection high-energy positron diffraction (RHEPD), which is a technique for the determination of the topmost- and near-surface atomic configurations; the total reflection of the positron beam from a solid surface is a unique superior characteristic. The present system provides the final beam of almost the same quality as the previous one with a 22Na-based positron beam [A. Kawasuso et al., Rev. Sci. Instrum. 75, 4585 (2004)] but much increased flux, i.e., almost the same emittance but much higher brightness. It gave a ∼ 60 times intensified diffraction pattern from a Si(111)–(7 × 7) reconstructed surface compared to the previous result. An improved signal-to-noise ratio in the obtained pattern due to the intensified beam allowed observation of clear fractional-order spots in the higher Laue-zones, which had not been observed previously.

Keywords

Positron Beam Magnetic Lens Brightness Enhancement 22Na Data High Energy Accelerator Research Organization 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Masaki Maekawa
    • 1
  • Ken Wada
    • 2
  • Yuki Fukaya
    • 1
  • Atsuo Kawasuso
    • 1
  • Izumi Mochizuki
    • 2
  • Tetsuo Shidara
    • 3
  • Toshio Hyodo
    • 2
  1. 1.Advanced Science Research CenterJapan Atomic Energy AgencyGunmaJapan
  2. 2.Institute of Materials Structure ScienceHigh Energy Accelerator Research Organization (KEK)Tsukuba, IbarakiJapan
  3. 3.Accelerator LaboratoryHigh Energy Accelerator Research Organization (KEK)Tsukuba, IbarakiJapan

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