2000 Fiscal Year Final Research Report Summary
A precise measurement of the cosmic-ray antiprotons in the solar minimum period and a study of their origin
| Project/Area Number |
09304033
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Kobe University |
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Principal Investigator |
NOZAKI Mitsuaki Kobe University Graduate School of Science and Technology, Professor, 自然科学研究科, 教授 (10156193)
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| Co-Investigator(Kenkyū-buntansha) |
TETSUYA Yoshida High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Associate Professor, 素粒子原子核研究所, 助教授 (50222394)
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| Project Period (FY) |
1997 – 2000
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| Keywords | cosmic ray / antiproton / spectrometer / balloon experiment |
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| Research Abstract |
We have carried out four balloon observations using the BESS spectrometer. The payload was launched at Lynn Lake, Canada, where the geomagnetic cut-off rigidity is low. The solar activity was at the most quiet phase in 1997 and then it gradually increased. It has been reported that the solar magnetic polarity has been changed in 2000. Hundreds of cosmic ray antiprotons together with protons and helium nuclei collected during the term of this project have provided valuable data to study the origin of antiprotons and the mechanism of galactic propagation and solar modulation. We have observed a peak in the antiproton spectrum at around 2 GeV, characteristic of the secondary antiprotons, and established that the majority of cosmic ray antiprotons are the secondary products of the interaction between primary cosmic rays and the interstellar medium.
We have also measured cosmic rays at a mountain altitude to study the development in the atmosphere. In order to perform the above studies, we have upgraded the BESS spectrometer ; improvement in the time-of-flight resolution, installation of an aerogel Cherenkov counter and shower counters and upgrade of the data acquisition system.
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