Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||Department of Physics, Faculty of Science, Hiroshima University|
SUMI Yoshio Department of Physics, Faculty of Science, Hiroshima University Professor, 理学部, 教授 (20029490)
NAGAMIYA Shoji Nevis Laboratories, Columbia University, Professor, ネヴィス研究所, 教授
BOGGILD H Niels Bohr Institute, Copenhagen University, Professor, ボーア研究所, 教授
FABJAN C CERN,PPE Division, Sencor Investigator, 主任研究員
IWATA Yosei Department of Physics, Faculty of Science, Hiroshima University Research Associa, 理学部, 助手 (20168579)
SAKAGUCHI Atsushi Department of Physics, Faculty of Science, Hiroshima University Research Associa, 理学部, 助手 (70205730)
SUGITATE Toru Department of Physics, Faculty of Science, Hiroshima University Associate Profes, 理学部, 助教授 (80144806)
MIYAMURA Osamu Department of Physics, Faculty of Science, Hiroshima University Professor, 理学部, 教授 (80029511)
BOGGILD H. コペンハーゲン大学ニールス, ボーア研究所, 教授
FABJAN C. ヨーロッパ共同粒子物理学研究所, 主任研究員
西村 俊二 日本学術振興会, 特別研究員
米澤 穰 広島大学, 理学部, 教授 (70033800)
FABJAN C.W. ヨーロッパ共同粒子物理学研究所, 主任研究員
|Project Period (FY)
1993 – 1995
Completed(Fiscal Year 1995)
|Budget Amount *help
¥17,000,000 (Direct Cost : ¥17,000,000)
Fiscal Year 1995 : ¥5,000,000 (Direct Cost : ¥5,000,000)
Fiscal Year 1994 : ¥6,000,000 (Direct Cost : ¥6,000,000)
Fiscal Year 1993 : ¥6,000,000 (Direct Cost : ¥6,000,000)
|Keywords||High-energy heavy ion collisions / Multiple particle production / Quark-gluon plasma / Two-particle interferometry / CERN-SPS accelerator / NA44 collaboration / NA44実験 / 運動量収束型スペクトロメータ / CERN-SPS / HBT効果 / 高エネルギー重イオン反応 / ハンブリー・ブラウン / ツィス効果 / 運動量収束型スペクトルメータ / クォーク・グル-オン・プラズマ|
We have organized an international collaboration group NA44. The NA44 has carried out one and two particle measurement in heavy-ion collisions at the CERN-SPS.The experimental data with 450-GeV proton, 200A CeV sulphur and 160A GeV lead have been accumulated. In particular, the lead beam data have been taken for the first time in the world and for this data taking we employed a new type of Cherenkov counter (threshold imaging Cherenkov) wihch has been developed by the CERN-Hiroshima group. The NA44 group has been continuing the data reduction and analysis work and many interesting features have been found for the hadronic matter generated in heavy-ion collisions at the CERN-SPS energies. They are summarized as follows :
In the transverse momentum (P_T) distribution other group has reported anomalous enhancement at low P_T and target rapidity. We have, however, found only small enhancement at low P_T and mid-rapidity. This small enhancement is consistent with the effect of resonance production.
(2) Deuteron and anti-deuteron are detected and the validity of the coalescence model is examind. The relative production rate of deuteron and antideuteron production seems to increase as P_2 increases.
(3) From the HBT analysis, the size parameters of hadronic source produced in high-energy heavy-ion collisions are determined for pion and kaon.The transverse mass (m_T) dependence of these parameters confirms the existence of the transverse expansion and flow which have been predicted by the hydro-dynamical model.
(4) The width of pion-freezeout time distribution, which has been expected theoretically but not observed so far experimentally, is determined for the first time in the world. The observed values are not so large as expected from the occurence of QGP phase transition.
(5) The HBT parameters for both pion and kaonare described by a single function of only m_T and the observed difference between those of pion and of kaon is simply due to their mass difference.