在RHIC质心系能量每核子对200GeV的氘金对撞和质子质子对撞中的pion,kaon,proton和antiproton粒子谱

摘要

本论文详细报告了对200GeV质子质子对撞和氘金对撞中产生的π<'±>.K<'±>和p(p<'->)等粒子的研究结果.本文所分析的数据为RHIC对撞机上的STAR探测器于2003年所采集的质子质子对撞和氘金对撞的数据.本文运用了新型的多隙电阻板室的飞行时间谱仪,在中快度区间(-0.5,K<'±>和p(p<'->)等粒子进行了仔细的测量研究.这是多气隙电阻板室,这种新型的气体时间探测器,第一次在对撞机实验中的实际运用.同时也是在高能的氘金对撞中,对π<'±>,K<'±>和p(p<'->)等粒子的首次测量和研究.在参与了MRPC的研制和MC模拟及对探测器工作机制有了充分理解的基础上,本论文提出了一套刻度方法,在相当短的时间内完成了对MRPC的数据校正,实现粒子识别,为物理数据分析提供可靠的基础.这种刻度方法成功地运用于STAR的实验中,使多气隙电阻板室的时间分辨达到85ps,在2003年的氘金对撞和质子质子对撞中,对π<'±>,K<'±>的粒子分辨达到横动量1.6GeV/c,对p(p<'->)的粒子分辨可达到横动量3.0GeV/c.从而在STAR上实现了将可鉴别粒子谱扩展到中等横动量区,此项工作也证实了MRPC-TOF系统在重离子对撞机环境下的可行性.论文详细讨论了引起Cronin效应的各种物理因素.将实验结果与initial multiple parton scattering model [30]做了比较,并用recombination model[92]来具体计算pion和proton粒子谱,发现recombination model的计算结果和实验数据符合得较好.从这些比较的结果来看,我们认为在质心系能量200 GeV的氘金对撞中,Cronin效应并非纯然是初态效应,末态效应起着重要作用.这些物理结果出现在e-Print Archives(nu-ex/0309012)并提交发表.从建立在MRPC的这个小的tray模型得到的良好的粒子鉴别能力和重要的物理结果给STAR合作组的full-time-of-flight-system proposal奠定了坚实的基础.

目录

文摘

英文文摘

Acknowledgments

Chapter 1 Physics

1.1 Deconfinement and phase diagram

1.2 Relativistic Heavy Ion Collisions

1.3 The experimental results at RHIC

1.3.1 Flow

1.3.2 High pT suppression and di-hadron azimuthal correlation

1.3.3 Particle composition in Au+Au at intermediate pT

1.3.4 Summary

1.4 Cronin effect

1.4.1 Why we need d+Au run at RHIC

1.4.2 Lower energy

1.4.3 Predictions: RHIC energy

Chapter 2The STAR Experiment

2.1 The RHIC Accelerator

2.2 The STAR Detector

2.2.1 The Time Projection Chamber

2.2.2 The tine-of-flight tray based on MRPC technology

Chapter 3 Analysis Methods

3.1 Trigger

3.1.1 Centrality tagging

3.1.2Triggerbiasstudy

3.2Trackselectionandcalibration

3.2.1 Calibration

3.3 Raw yield

3.3.1 π raw yield extraction

3.3.2 K raw yield extraction

3.3.3 p and p raw yield extraction

3.4 Efficiency and acceptance correction

3.5 Background correction

3.6 Energy loss correction

3.7 Normalization

Chapter 4 Results

4.1 π. K, p and p spectra in d+Au and p+p collisions at mid-rapidity

4.1.1 Systematic uncertainty

4.2 Cronin effect

4.3 p + p/h ratio in d+Au and p+p collisions at middle pseudo-rapidity

4.4 K/π, p/π and anti-particle to particle ratios

4.5 dN/dy, 〈pT〉, and model fits

4.6 System comparison

Chapter 5 Discussion

5.1 Cronin effect

5.1.1 Model comparison: initial state effect?

5.1.2 Model comparison: recombination

5.1.3 Integral yield RdAu: shadowing effect?

5.1.4 Initial or final state effect: Drel1-Yan process

5.2 Baryon excess in Au+Au collisions

5.2.1 p/p ratio vs pT

5.2.2 Baryon production at RHIC: multi-gluon dynamics?

Chapter 6 Conclusion and Outlook

6.1 Conclusion

6.2 Outlook

6.2.1 Cronin effect at 200 GeV: Mass dependent or baryon/meson　dependent?

6.2.2 Electron PID from MRPC-TOFr

6.2.3 Full-TOF Physics

6.2.4 63 GeV Au+Au collisions at RHIC

APPENDIX A Tables of the Invariant Yields

APPENDIXB How to make MRPC

B.1 Preparations

B.1.1 Glass

B.1.2 Carbon Layer

B.1.3 Mylar layer

B.1.4 Honeycomb board

B.1.5 The printed circuit board (PCB)

B.1.6 Lucite cylinder

B.1.7 Other stuff

B.2 Installation

B.2.1 The outer glass and mylar and PCB

B.2.2 Inner glass and fish-line coiling

APPENDIXC List of Publications

APPENDIXD STAR Collaboration

Bibliography