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1999 Fiscal Year Final Research Report Summary

Precise test of electromagnetic interactions in ortho-positronium spectroscopy

Research Project

Project/Area Number 09304034
Research Category

Grant-in-Aid for Scientific Research (A)

Allocation TypeSingle-year Grants
Section一般
Research Field 素粒子・核・宇宙線
Research InstitutionTokyo Metropolitan University (TMU)

Principal Investigator

HIROSE Tachishige  TUM, Graduate school of science, Professor, 理学研究科, 教授 (70087162)

Co-Investigator(Kenkyū-buntansha) KUMITA Tetsuro  TUM, Graduate school of science, Research associate, 理学研究科, 助手 (30271159)
CHIBA Masami  TUM, Graduate school of science, Research associate, 理学研究科, 助手 (60128577)
HAMATSU Ryosuke  TUM, Graduate school of science, Associate professor, 理学研究科, 助教授 (20087092)
YABU Hiroyuki  TUM, Graduate school of science, Research associate, 理学研究科, 助手 (60202371)
IRAKO Mitsuhiro  TUM, Graduate school of science, Research associate, 理学研究科, 助手 (60087004)
Project Period (FY) 1997 – 1999
KeywordsPositronium / Laser cooling / Doppler shift / Slow positron beam / Thermal positronium
Research Abstract

1) Production system of positronium (Ps) : We installed a mesh-moderator in the slow ortho-positron (oPs) generator constructed at TMU and were able to increase the intensity of slow oPs by more than one order. A chopper-buncher system created the bunched oPs beam with the time width of 1ns. For achieving efficient collisions of oPs with laser, we have developed a new method of positron accumulation by converting the longitudinal momentum to the transverse one while positron is traveling in magnetic fields. Thermal oPs was efficently produced using a high temperature Mo target heated up to 1000 K and the production rate was measured by means of time-of-flight method.
2) Laser system : For the excitation of oPs, we fabricated a Cr : LiSAF laser which provides a long pulse of 200 ns (longer than the oPs lifetime of 142 ns.) having a wave length of 243 nm, sufficiently wide line width to cover the initial Doppler broadening and the repetitio of 25 Hz. The second harmonic and forth harmonic genrators are optimized with respect to the oputput power and the line woidth. We transported the laser to the collision point and made an irradiation test.
3) 1S→2P laser excitation : Using Monte Carlo simulation, we examined in detail geometrical condition of laser irradiation, variation of the lifetime owing to the stimulated cooling, mutual relation between laser and positron beams.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] H.Iijima 他: "Laser Cooling System of ortho-positronium"Nuel.Inst. & Nethi Phys.Res.1. 455. 104-108 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.Iijima 他: "Monte Certo study of ortho-positronium …"Jour.Phys.Soc.Jap.. (To be published). (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Kumita 他: "Development of positronium trap …"App.Sur.Sci.. 149. 106-109 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] N.N.Mondal 他: "Construction of time of flight …"App.Sur.Sci.. 149. 269-275 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Nishimura 他: "Positronium rave annihilation …"App.Sur.Sci.. 149. 276-281 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Chiba 他: "Four and five photon decay …"Nucl.Inst. & Meth.Phys.Res.B. 143. 121-126 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.lijima et al.: "Laser cooling suystem of ortho-positronium"Nucl.Inst. & Meth.Phys.Res.A. 455. 104-108 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H.lijima et al.: "Monte Carlo study of ortho-positronium laser cooling suystem"Jour.Phys.Soc.Jap.. (To be published). (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.kumita et al.: "Development of positronium trap for laser cooling"App.Sur.Sci.. 149. 106-109 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] N.N.Mondal et al.: "Construction of time-of -flight measurement system"App.Sur.Sci.. 149. 269-275 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Nishimura et al.: "Positronium rare annihiation experiment with a positron beam line"App.Sur.Sci.. 149. 276-281 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M.Chiba et al.: "Four and five photon decayfrom positronium and the lifetime problem"Nucl.Inst. & Meth.Phys.Res.B. 143. 121-126 (1998)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2002-03-26  

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