1991 Fiscal Year Final Research Report Summary
Data Analysis of High-Energy Nucleus-Nucleus Collision Experiment NA44
| Project/Area Number |
02452026
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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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 | HIROSHIMA UNIVERSITY |
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Principal Investigator |
SUMI Yoshio Hiroshima Univ. Physics Dept. Professor, 理学部, 教授 (20029490)
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| Co-Investigator(Kenkyū-buntansha) |
MAEHARA Toshinobu Hiroshima Univ. Dept. of Science Education Assistant Professor, 学校教育学部, 講師 (50190319)
MIYAMURA Osamu Hiroshima Univ. Physics Dept. Associate Professor, 理学部, 助教授 (80029511)
IWATA Yousei Hiroshima Univ. Physics Dept. Research Associate, 理学部, 助手 (20168579)
SAKAGUCHI Atsushi Hiroshima Univ. Physics Dept. Research Associate, 理学部, 助手 (70205730)
SUGITATE Toru Hiroshima Univ. Physics Dept. Research Associate, 理学部, 助手 (80144806)
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| Project Period (FY) |
1990 – 1991
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| Keywords | High-energy heavy-ion collisions / Quark-gluon plasma / Hambury-Brown / Twiss effect / Momentum-focussing spectrometer / CERN-SPS accelerator / Two-particle interferometry |
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| Research Abstract |
1. By means of a momentum focussing spectrometer, a large amount of raw data on 450-GeV proton-nucleus and 200-GeV/nucleon sulphur-nucleus collisions have been accumulated at the CERN-SPS accelerator.
2. For the sulphur beam, we developed a new type of gas Cherenkov counter. The counter worked successfully and achieved a time resolution of 35 ps, which is the best in the world.
3. The data have been analyzed at the Department of Physics, Hiroshima University. In this analysis, special emphasis is put on precise particle identification as well as on high statistics. The analysis determined the following quantities:
(1) Singles spectra for various hadrons appearing in the final state.
(2) Two-particle correlation functions for pi^*pi^* and KAPPA^*KAPPA^*.
4. Singles spectra can be described by an exponential function of the transverse mass M_T and the lighter the particle, the steeper the slope.
5. The spectra also show that any anomalous enhancement, the existence of which has been claimed at small momentum transfers by some authors, does not exist at all.
6. The hadron source sizes are determined from the observed two-particle correlation functions. The pion source size increases from 2 fm for p+Pd collisions to 5 fm for S+Pb collisions.
7. The pion source size is about twice as large as the kaon source size, implying an earlier freeze-out of kaons than pions.
8. No substantial difference is seen between the KAPPA^+ and KAPPA^- source sizes in S+Pb interaction.
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