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Study of photo-neutron reaction below the pion threshold

介子阈值以下的光中子反应研究

基本信息

批准号：
05044030
负责人：
TERASAWA Tatsuo
金额：
$ 3.52万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

Main purpose of the profect was to elucidate the role of meson exchange current in photonuclear reactions. Tohoku and Melbourne resarchers have collaborated in photonuclear experiments using tagged photon faility of Tohoku University since 1982. The collaboration has found the importance of two nucleon absorption process in photonuclear reactions above the giant resonances but below the photo-pion threshold. Further detailed studies of the two-nucleon absorption mechanism have been pursued in the present short term project.In the first stage of the project, we have prepared experimental environment such as constructions of a new beam line, large volume neutron detectors and a new data acquisition system. All of these have been completed with success, and the performanses have been published.Collaborative experiments caried out in this term of the project are ^<16>O(gamma, n), ^<12>C(gamma, n) and ^<31>P(gamma, p). Also^<12>C(gamma, p) which was made before the project has been reanalyzed and published in Phys. Rev.C.One of the Melbourn collaborator, G.J.O'keefe, has completed his PhD thesis by the ^<16>O(gamma, n) result. The analysis of the ^<31>P(gamma, p) experiment has been finished. We have found a large population to the giant resonance region of the residual ^<30>Si nucleus, which shows a clear evidence of the interaction of photons with the meson exchange current. A part of the results has been presented at 1995 ICTP conference in Trieste/Itary.Altogether 6 researchers from Tohoku university have visited Melbourne university in 1994-1995. Altogether 9 researchers from Melbourne university have visited Tohoku university in 19941995.In January, 1996,3 researchers from Melbourne university have been invited to Tohoku university for discussions on the collaboration.In March, 1996,2 researchers from Melbourne university will be invited for the workshop on next collaborative experiments.

本文的主要目的是阐明介子交换流在光核反应中的作用。自1982年以来，东北大学和墨尔本大学的研究人员一直在利用东北大学的标记光子衰变进行光核实验。该合作发现了两核子吸收过程在巨共振以上但低于光π阈值的光核反应中的重要性。在本短期项目中，我们对双核子吸收机制进行了进一步的详细研究，在项目的第一阶段，我们准备了实验环境，如新的束线，大体积中子探测器和新的数据采集系统的建设。本项目期内进行的合作实验有^<16>O（gamma，n），^<12>C（gamma，n）和^<31>P（gamma，p）。此外，在<12>该项目之前所做的^ C（gamma，p）已经被重新分析并发表在Phys. Rev.C上。梅尔伯恩的合作者之一G. J. O 'keefe已经通过^<16>O（gamma，n）结果完成了他的博士论文。完成了^<31>P（gamma，p）实验的分析。我们在剩余^ Si核的巨共振区发现了大量<30>的粒子数，这为光子与介子交换流的相互作用提供了明确的证据。1994-1995年东北大学6名研究人员访问了墨尔本大学，并在1995年的里雅斯特国际理论物理中心会议上作了部分报告。19941995年，墨尔本大学的9名研究人员访问了东北大学。1996年1月，墨尔本大学的3名研究人员应邀访问东北大学，讨论合作问题。1996年3月，墨尔本大学的2名研究人员将应邀参加下一次合作实验的研讨会。