Experimental study of high energy hadronic matter

高能强子物质实验研究

• 批准号: 05044058
• 负责人: SUMI Yoshio
• 金额: $ 10.88万
• 依托单位: Department of Physics, Faculty of Science, Hiroshima University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05044058/
• 关键词: 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

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.

我们组织了一个国际合作小组NA44。NA44已经在CERN-SPS上进行了重离子碰撞中的单粒子和双粒子测量，积累了450 GeV质子、200A CEV硫和160A GeV铅的实验数据。特别是，铅束数据在世界上是第一次获得，为了获得这种数据，我们使用了一种新型的切伦科夫计数器(阈值成像切伦科夫)，这是由CERN-广岛小组开发的。NA44小组一直在继续数据简化和分析工作，并在CERN-SPS能量下发现了重离子碰撞产生的强子物质的许多有趣的特征。总结如下：在横向动量(P_T)分布中，另一组在低P_T和目标快速处有异常增强。然而，我们发现在低P_T和中快区只有很小的增强。这种微小的增强与共振产生的效应是一致的。(2)探测到了重离子和反重离子，验证了聚结模型的正确性。从HBT分析中确定了高能重离子碰撞中产生的强子源的尺寸参数。这些参数与横向质量(MT)的关系证实了流体力学模型所预测的横向膨胀和流动的存在。(4)首次确定了理论上预期但实验上尚未观察到的π介子冻结时间分布的宽度。由于QGP相变的发生，观测值并不像预期的那样大。(5)介子和介子的HBT参数都只用m_T的单一函数来描述，而介子和介子的HBT参数的观测差异仅仅是由于它们的质量不同。

项目成果

H.Boggild, et al.: "Low p_T phenomena in A+A and p+A collisions at mid-rapidity" Zeitschrift for Physik. in press. (1996)

H.Boggild 等人：“A A 和 p A 中速碰撞中的低 p_T 现象”Zeitschrift for Physik。

S.Nishimura: "Two-Particle Correlation Measurement in S+Nucleus Collisions at 200GeV/c per Nucleon" Joun.Sci.Hiroshima Univ.Sereis A.58. 1-108 (1994)

S.Nishimura：“每核子 200GeV/c 下 S 核碰撞中的双粒子相关测量”Joun.Sci.Hiroshima Univ.Sereis A.58。

H.Boggild, et al.: "Coulomb effect in single particle distributions" Physics Letters. B(in press). (1996)

H.Boggild 等人：“单粒子分布中的库仑效应”《物理快报》。

H.Beker et al.: "Identified pion interferometry in heavy-ion collisions at CERN" Physics Letters. B302. 510-516 (1993)

H.Beker 等人：“在 CERN 重离子碰撞中识别出π介子干涉测量法”《物理快报》。

H.Beker et al.: "m_T dependence of boson interferometry in heavy-ion collisions at the CERN SPS" Physical Review Letters. (in press). (1995)

H.Beker 等人：“CERN SPS 重离子碰撞中玻色子干涉测量的 m_T 依赖性”物理评论快报。