Study of state with high temperature and high density using jets and quarkonia as probes

2002 ~ 2005年，在RHIC PHENIX上进行了实验运行，并以喷流和夸克偶素为探针进行了研究，通过对d+Au碰撞和Au+Au碰撞的核修正因子的实验测定，一致认为高动量区产额的抑制主要归因于部分子的能量损失（喷流淬灭）。积累了碰撞能量、碰撞核素和中心性函数的各种组合的数据，以建立系统趋势。对单电子的核修正因子也进行了测量，发现粲夸克也有相当大的能量损失。这一结果要求我们重新评价已被广泛采用的能量损失机制，并确定了p+p碰撞的J/N产额，以明确反应机制，并为重离子数据提供参考。采用d+Au碰撞的J/Eq产额数据，并与包含初始核效应和末阶段核吸收的理论计算进行了比较。最后，对Au+Au和Cu+Cu碰撞进行了计算，并与各种理论计算结果进行了比较。目前，最适合的计算包括QGP中的J/π抑制和强子化过程中的复合过程。在RHIC实验研究的同时，LHC的准备工作也在进行中。首先，根据RHIC的结果列出了重要的主题。高动量粒子和夸克偶子的测量被选为主要议题。研制了跃迁辐射探测器（TRD），并进行了性能研究.最后，原型与生产规模进行了测试，以证明他们满足要求。

During the time period from 2002 to 2005, experimental runs were executed at the PHENIX of RHIC, and studies have been performed using jets and quarkonia as probes.From the experimental determination of nuclear modification factor for d+Au collisions and for Au+Au collisions, it was unanimously concluded that suppression of yield in the high momentum region is mainly ascribed to the energy loss of partons (jet quenching). Accumulation of data have been made for various combinations of colliding energy, colliding nuclear species and as a function of centrality, in order to establish systematic trend. Nuclear modification factor was also measured for single electrons, to find out that charm quark also suffer rather large energy loss. This result demands us to re-evaluate the well adopted energy-loss mechanism.J/Ψ yield was determined for p+p collisions, which is used to make clear the reaction mechanism and is supposed to serve as a reference to heavy-ion data. J/Ψ yield data was taken for d+Au collisions, and was compared with a theoretical calculation which includes both initial nuclear effects and nuclear absorption in the final stage. Finally, some data were obtained for Au+Au and Cu+Cu collisions, and the results have been compared with various theoretical calculations. At this moment, the best fit seems to be obtained in the calculations which include both mechanisms ; J/Ψ suppression in the QGP and recombination process in the hadronization prpcess.In parallel to the experimental investigations at RHIC, preparative works have been performed towards LHC. First of all, important subjects were listed up based upon the results at RHIC. Measurement of high momentum particles and quarkonia were chosen to be the main topics. Development of TRD (transition radiation detector) was made, and performance studies were performed. In the end, prototypes with production-size was tested to prove that they fulfill the requirements.