| Project/Area Number |
02402004
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | Kobe University (1992-1993)
The University of Tokyo (1990-1991) |
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Principal Investigator |
NOZAKI Mitsuaki Kobe University, Faculty of Science, Department of Physics, Assistant Professor, 理学部, 助教授 (10156193)
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| Co-Investigator(Kenkyū-buntansha) |
IMORI Masatoshi University of Tokyo International Center for Elementary Particle Physics Researc, 素粒子物理国際研究センター, 助手 (70011690)
山本 明 高エネルギー物理学研究所, 助教授 (30113418)
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| Project Period (FY) |
1990 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥28,000,000 (Direct Cost: ¥28,000,000)
Fiscal Year 1993: ¥4,300,000 (Direct Cost: ¥4,300,000)
Fiscal Year 1992: ¥8,400,000 (Direct Cost: ¥8,400,000)
Fiscal Year 1991: ¥8,100,000 (Direct Cost: ¥8,100,000)
Fiscal Year 1990: ¥7,200,000 (Direct Cost: ¥7,200,000)
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| Keywords | cosmic rays / anti-proton / anti-heliums / magnet spectrometer / 反物質宇宙線 / 気球搭載測定器 / 宇宙起源反粒子 / ガーマ線点源 / ガンマ線点源 / 超伝導スペクトロメ-タ |
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| Research Abstract |
The BESS experiment (Balloon-borne Experiment using a Superconducting magnet Spectrometer) was planned and the BESS detector was developed to investigate an origin of cosmic ray anti-particles such as anti-protons and anti-helium nuclei. The spectrum of secondary anti-protons are extremely low below 1 GeV due to the kinematical suppression. On the other hand, the anti-protons expected from the hypothetical sources such as the annihilation of neutralino dark matter particles or the evaporation of primordial black holes give rather flat spectrum. Therefore low energy anti-protons are sensitive to those exotic origins.
The detector system consisted of a thin superconducting solenoidal magnet, a cylindrical jet-drift chamber, 4 layrs of arc-shaped drift chambers and time-of-flight counters. The cylindrical configuration of the BESS detector provided a wide tracking volume and a large geometrical acceptance.
The balloon flight of the BESS was carried out at Lynn Lake, Canada, in July 1993. The instrument flew at an altitude of 36.5 km for 14 hours. A total of 4 million events were recorded during the flight.
We detected 4 anti-protons including 0.4 events of beckground at energies below 500 MeV.This was the first positive measurement of the low energy anti-protons. The ratio of anti-proton flux to proton was calculated and it was found to be consistent with the model of the secondary production, though the model has still large uncertainties.
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