Study on Quark-Gluon-Plasma in the High Energy Heavy Ion Collision

高能重离子碰撞中夸克-胶子-等离子体的研究

基本信息

批准号：
63044034
负责人：
HOMMA Saburo
金额：
$ 7.68万
依托单位：
Institute for Nuclear Study, University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63044034/
关键词：
High Energy Heavy Ion Collision QuarkGluonPlasma QGP Phase Transition High Energy and High Density Nuclear Matter

项目摘要

Final goal of this research project is to detect and investigate a Quark-Gluon Plasma (QGP), a new phase of high-energy and high-density nuclear matter which is expected to be formed by the high energy heavy ion collisions. As a first step of this study of new phase of nuclear matter, we started from the measurements of the inclusive spectra of pions, kaons, and protons produced by the heavy ion collisions at the incident energy of 14.5 GeV/nucleon at BNL-AGS.The measured transverse kinetic energy distributions of hadrons are well described by an exponential form in the measured region. The inverse slope (slope parameter) for protons is found to be larger than that of pions at the rapidity region from 1.1 to 1.5 in Si-induced reactions, whereas the slope parameter depends neither on emitted particle species nor on mass number of target nuclei.The yield ratio of kaons to pions is especially interesting because several theories predict this ratio will be a good signal of the QGP formation. In our measurements this ratio was found to be 14.9 % for positive kaons and pions, and 4.7 % for negative kaons and pions in Si-Au collisions. After the corrections for the spectator effects, the above ratios in the participant region become 8% for positive particles and 3% for negative particles. Although these ratios are by a factor of 1.5 larger than in p-p collisions, they are not as large as the predicted ratios from the QGP. However, the continuous study of this effect will be necessary.Besides these hadron measurements, we did the computer simulations to study the possibility of detecting the electron-positron pair as a signal of the QGP formation. Considering the results of this simulation, we designed and constructed the detector systems and performed the test experiments for the detection of electron-positron pair.

该研究项目的最终目标是检测和研究夸克 - 胶状等离子体（QGP），这是一个高能量和高密度核物质的新阶段，预计将由高能量重离子碰撞形成。作为对核物质新阶段的研究的第一步，我们从重型离子碰撞在BNL-AG处的14.5 GEV/Nocleon产生的呈乳头，kaons和质子的包含光谱的测量开始。发现质子的逆斜率（斜率参数）比SI诱导的反应中的速度区域的乳头质量大于1.1至1.5，而斜率参数既不取决于发射的粒子物种，也不取决于质量的靶核数量。尤其有趣的是，KAONS与pions的质量尤其有趣，因为几个理论预测了该比率是良好的信号。在我们的测量中，发现正峰和亲能力率为14.9％，在SI-AU碰撞中为负的Kaons和Pions为4.7％。校正观众效应后，正粒子的上述比率为8％，负颗粒的比率为3％。尽管这些比率比p-p碰撞大1.5倍，但它们不如QGP的预测比率大。但是，对这种效果的持续研究是必要的。底发测量值，我们进行了计算机模拟，以研究检测电子 - 峰值对作为QGP形成的信号的可能性。考虑到该模拟的结果，我们设计并构建了检测器系统，并进行了测试实验，以检测电子峰值对。