2005 Fiscal Year Final Research Report Summary
Study of state with high temperature and high density using jets and quarkonia as probes
| Project/Area Number |
14204021
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HAMAGAKI Hideki The University of Tokyo, Graduate school of Science, Associate Professor, 大学院・理学系研究科, 助教授 (90114610)
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| Co-Investigator(Kenkyū-buntansha) |
OZAWA Kyoichiro The University of Tokyo, Graduate School of Science, Research Associate, 大学院・理学系研究科, 助手 (20323496)
MIAKE Yasuo University of Tsukuba, Graduate school of Pure and Applied Sciences, Professor, 大学院・数理物質科学研究科, 教授 (10157422)
SUGITATE Toru Hiroshima University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (80144806)
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| Project Period (FY) |
2002 – 2005
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| Keywords | quark gluon plasma / QCD / high-energy heavy-ion collisions / RHIC / LHC / confinement / early universe / PHENIX experiment |
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| Research Abstract |
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.
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