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Precision Measurement of 4 and 5 photon decay in positronium

Research Project

Project/Area Number 08454068
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 素粒子・核・宇宙線
Research InstitutionTOKYO METROPOLITAN UNIVERSITY

Principal Investigator

CHIBA Masami  Tokyo Metropolitan Univ., Physics Dept., Reserch Associate, 大学院理学研究科, 助手 (60128577)

Co-Investigator(Kenkyū-buntansha) KUMITA Tetsurou  Tokyo Metropolitan Univ., Physics Dept., Reserch Associate, 大学院理学研究科, 助手 (30271159)
HAMATSU Ryousuke  Tokyo Metropolitan Univ., Physics Dept., Associate Professor, 大学院理学研究科, 助教授 (20087092)
HIROSE Tachishige  Tokyo Metropolitan Univ., Physics Dept., Professor, 大学院理学研究科, 教授 (70087162)
Project Period (FY) 1996 – 1997
Project Status Completed (Fiscal Year 1997)
Budget Amount *help
¥7,100,000 (Direct Cost: ¥7,100,000)
Fiscal Year 1997: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1996: ¥6,600,000 (Direct Cost: ¥6,600,000)
Keywordspositron / positronium / higher order QED process / charge conjugation / GSO scintillator / 4 and 5 photon decay / positron beam / ortho-positronium lifetime
Research Abstract

In 1996 we published the first results of the measurement of 5 photon decay from ortho-positronium. This was the first test of the 8th order of a without including the lower order in QED.In the second paper we published the results of the measurement of the charge conjugation invariance in 4 photon decay from ortho-positronium. It is inhibited by charge conjugation invariance to decay even number of photons. By the Grant-in Aid we presented and discussed in the international conference held at Poland. The contents were published in the third paper.
In 1997 we prepared to use the slow positron beam facility at the National Laboratory for High Energy Physics. The experiment had been approved as the experiment 95-G158. We set the multi-gamma ray spectrometer at the down stream of the line and connected by high vacuum pipe. In order to introduce the beam to the center of the spectrometer, we generated a magnetic field by selenoidal and Helmholz coils. After the preparetion we succeeded to t … More ransport the beam to the entrance of the spectrometer. But we did not have enough time to do the experiment since the slow positron beam line should to move due to the construction of the injector for the B factory. After that we studied the positron beam transport line with alternating magnetic field along the beam line using radially magnetized cylindrical permanent magnets. The preliminary experimental results are encouraging. They have some advantages over electromagnets. They generate strong magnetic field with small magnetic flux leakage, have no power dissipation to heat the environment and are compact. The relevant results was presented at the international conference held at South Africa andwill appear in the fifth paper. We have studied and planed for the new spectrometer to have 10 times larger acceptance for the 4 and 5 photon-decay compared to the existing spectrometer furnished with 32 NaI scintillators. The new one has 92 GSO scintillators to detect the photons. Discrepancy between QED and experiments concerning to the lifetime of ortho-positronium have been reported by Michigan Univ.group. In order to resolve the puzzle, we have studied a spectrometer to utilize 6 GSO scintillators to detect the decay 2 and 3 photons from ortho-positronium in good separation. By the Grant-in Aid we presented and discussed about the theme in the international conference held at England. The contents were published in the fourth paper. Less

Report

(3 results)
  • 1997 Annual Research Report   Final Research Report Summary
  • 1996 Annual Research Report
  • Research Products

    (16 results)

All Other

All Publications (16 results)

  • [Publications] Toshihiro Matsumoto et al.: "Measurement of five-photon decay in orthopositronium" Physical Review A. 54・3. 1947-1951 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Jinfeng Yang et al.: "Four-photon decay of orthopositronium : A test of charge-conjugation invariance" Rhysical Review A. 54・3. 1952-1956 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] M. Chiba et al.: "Measurement of Electron-Positron Annihilation at rest into Four and Five Photons" NUKLEONIKA. 42・1. 61-68 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Masami Chiba et al.: "Four and Five Photon Decay from Positronium and the Lifetime Problem" Nucl. Instr. Meth. B143. 121-126 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Takuro Nishimura et al.: "Positronium Rare Annilation Experiment with a Positron Beam-line using Permanent Magnets" Applied surface Science. (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Toshihiro Matsumoto, Masami Chiba, Ryosuke Hamatsu, Tashishige Hirose, Jinfeng Yang and Jie Yu: "Measurement of five-photon decay in orthopositronium" Physical Review A.Vol.54・No.3. 1947-1951 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Jinfeng Yang, Masami Chiba, Ryosuke Hamatsu, Tashishige Hirose, Toshihiro Matsumoto and Jie Yu: "Four-photon decay of orthopositronium : A test of charge-conjugation invariance" Physical Review A.Vol.54・No.3. 1952-1956 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] M.Chiba, R.Hamatsu, T.Hirose, T.Matsumoto and J.Yang: "MEASUREMENT OF ELECTRON-POSITRON ANNIHILATION AT REST INTO FOUR AND FIVE PHOTONS" NUKLEONIKA. Vol.42・No.1. 61-68 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Masami Chiba, Ryosuke Hamatsu, Tashishige Hirose, Mitsuhiro Irako, Tetsuro Kumita, Toshihiro Matsumoto, Shinya Matsuo, Takuro Nishimura and Jinfeng Yang: "Four and five photon decay from positronium and the lifetime problem" Nucl.Instr.Meth.B143. 121-126 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Takuro Nishimura, Masami Chiba, Shinya Matsuo, Ryousuke Ogata, Kiyohiko Naka, Tashishige Hirose, Ryousuke Hamatsu, Mitsuhiro Irako and Tetsuro Kumita: "Positronium Rare Annihilation Experiment with a Positron Beam-line using Permanent Magnets" Applied Surface Science. (to be published). (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Toshihiro Matsumoto et al.: "Measurement of five-photon decay in orthopositronium" Physical Review A. 54.3. 1947-1951 (1996)

    • Related Report
      1997 Annual Research Report
  • [Publications] Jinfeng Yang et al.: "Four-photon decay of orthopositronium:A test of charge-conjugation invariance" Physical Review A. 54・3. 1952-1956 (1996)

    • Related Report
      1997 Annual Research Report
  • [Publications] M.Chiba et al.: "Measurement of Electron-Positron Annihilation at rest into Four and Five Photons" NUKLEONIKA. 42・1. 61-68 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Masami Chiba et al.: "Four and Five Photon Decay from Positronium and the Lifetime Problem" Nucl.Instr.Meth.B.(1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] Toshihiro Matsumoto et al.: "Measurement of five-photon decay in orthopositronium" Physical Review A. 54・3. 1947-1951 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Jinfeng Yang et al.: "Four-photon decay of orthopositronium : A test of charge-conjugation invariance" Physical Review A. 54・3. 1952-1956 (1996)

    • Related Report
      1996 Annual Research Report

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Published: 1996-04-01   Modified: 2016-04-21  

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