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Data Analysis of High-Energy Nucleus-Nucleus Collision Experiment NA44

高能核-核碰撞实验NA44数据分析

基本信息

批准号：
02452026
负责人：
SUMI Yoshio
金额：
$ 4.29万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

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.

1.利用动量聚焦谱仪，在CERN-SPS加速器上积累了大量450 GeV质子-核和200 GeV/核子硫-核碰撞的原始数据.对于硫束，我们研制了一种新型的气体切伦科夫计数器。该计数器工作正常，时间分辨率达到35 ps，是目前世界上最好的.这些数据已经在广岛大学物理系进行了分析。在这种分析中，特别强调的是精确的颗粒识别以及高统计。分析确定了以下几个量：（1）末态出现的各种强子的单态谱。(2)π ^*pi^* 和KAPPA^*KAPPA^* 的双粒子相关函数。单粒子谱可以用横向质量M_T的指数函数来描述，粒子越轻，斜率越陡.光谱还表明，任何异常增强，这已经被一些作者声称在小动量转移的存在，根本不存在。强子源的大小由观测到的两粒子关联函数确定。π介子源的尺寸从p+Pd碰撞的2 fm增加到S+Pb碰撞的5 fm。π介子源的尺寸大约是K介子源尺寸的两倍，这意味着K介子比π介子更早冻结。在S+Pb相互作用中，KAPPA^+和KAPPA^-源的大小没有明显的差别。