Systematic measurement of hadron production for the study of Quark-Gluon Plasma

用于夸克-胶子等离子体研究的强子产生的系统测量

基本信息

批准号：
06102004
负责人：
MIAKE Yasuo
金额：
$ 144万
依托单位：
Insutitute of Physics,Unibersity of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Specially Promoted Research
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06102004/
关键词：
Big Bang Quark Gluon Plasma Relativistic Heavy Ion Collisions Time of Flight Counter Directed Flow Elliptic Flow Directed Flow Elliptic Flow クォークグルオンプラズマ流体力学的振舞ビックバン超高温,高密度ハドロン生成飛行時間測定クオーク・グルオンブラズマ相対論的高エネルギー重イオン衝突ピツ

项目摘要

During the period of the birth of the Universe, it is speculated that the universe was in an unknown from of matter, called quark-gluon plasma (QGP). Unique opportunity to re-create the QGP in the laboratory is provided by high energy heavy ion collisions. Systematic study of hadron production in the collisions is essentially important for the basic understanding of the complex system, which might characterize the formation of the QGP.High resolution time-of flight (TOF) counters (resolution in sigma ; <85 ps), which provides the key role for the particle identification of the hadron, has been constructed. Pipeline readout circuits for high resolution TOF measurement have been developed together with Nevis Lab., Columbia University. Utilizing the TOF system, systematic measurement of the produced hadrons has been carried out in heavy ion collisions at the energy of <10 A GeV, 158A GeV and 100+100 AGeV as planned.Among several achievements, study of collective emissions of particles in PB+PB collisions at the energy of 158 A GeV/c is important. From an event-by-event analysis of the azimuthal correlation of protons emitted at the target rapidity region, directed flow has been observed as a first time at this energy of heavy ion collisions. The magnitude of the directed flow is found to be smaller than those observed at 10A GeV and also smaller than those predicted by RQMD model. This fact may suggest a softening of equation of state, which characterizes the formation of Quark Gluon Plasma. With respect to the reaction plane, determined from the measurement of the directed flow, azimuthal correlation of K+, pion and proton near mid-rapidity have been observed. In semi-central collisions, K+ mesons are found to be preferentially emitted out of the reaction plane while pions and protons are emitted in the reaction plane. The result suggest that the K+ emission is influenced by in-medium potential effects in addition to the collective flow effects.

在宇宙诞生期间，据推测，宇宙是从物质中不知名的，称为夸克 - 杜伦等离子体（QGP）。高能量重离子碰撞提供了重新创建实验室中QGP的独特机会。对复杂系统的基本了解，对碰撞中的强子产生的系统研究至关重要，这可能表征了QGP的形成。高分辨率飞行时间（TOF）计数器（Sigma中的分辨率； <85 PS），这为Hadron的粒子识别提供了关键作用。高分辨率TOF测量的管道读数电路已与哥伦比亚大学的Nevis Lab一起开发。利用TOF系统，按计划进行的重量离子碰撞中已经进行了系统的测量，以<10 a GEV，158A GEV和100+100 ageV的能量进行了较大的成就。在几项成就中，对Pb+PB碰撞中GEV/C能量的集体颗粒集体排放的研究很重要。从对目标速度区域发出的质子的方位角相关性的逐场分析来看，在重离子碰撞的这种能量中，第一次观察到了定向流动。发现定向流量的大小小于在10a GEV下观察到的幅度，也小于RQMD模型预测的流量。这一事实可能表明状态方程的软化，这表征了夸克gluon等离子体的形成。相对于反应平面，已经观察到了从定向流量的测量，K+，亲质和质子的方位角相关性接近中高度。在半中性碰撞中，发现K+介子优先从反应面中排出，而亲质和质子则在反应平面发出。结果表明，除集体流动效应外，K+发射还受到中等潜力效应的影响。