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Study of nucleon resonances in nuclei through(γ, η)and(γ, ρη)reactions

通过(γ, η)和(γ, ρη)反应研究原子核中的核子共振

基本信息

批准号：
10440067
负责人：
KASAGI Jirohta
金额：
$ 8.51万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10440067/
关键词：
nucleon resonances in nuclei S_<11> resonance medium effects of nuclear matter (γ, η) reaction η-meson production tagged photon multi-scintillation detector solid hydrogen target 標識化光子多重シンチレータ検出器固体水素 (α,η)反応多重シンチータ検出器系 ^<12>C(

项目摘要

(1) We have analyzed experimental data of the C, Al, Cu(γ, η) reactions, obtained at the Electron Synchrotron facility of INS.The deduced reaction cross sections show a broad resonance structure with a peak at around 900 MeV, for the first time. It is concluded that the resonance corresponds to the excitation and decay of the S_<11>(1535) resonance in a nucleus.(2) We have calculated the cross sections of (γ, η) reactions based on the quantum molecular dynamics model. The experimental data were compared with the calculations, and a possibility that the S11 resonance in nuclear medium becomes wider than in vacuum is suggested in the comparisons. In order to conclude definitely, however, much experimental work is needed to get more accurate data in detail.(3) We have constructed the STB Tagger at Laboratory of Nuclear Science in Tohoku University, which produces GeV tagged photons of good quality from the STB ring.(4) In order to measure η-mesons efficiently, we have designed and constracted a multi-detector system called SCISSORS, which consists of more than 200 pure CsI scintillators.(5) We have measured η Photoproduction reactions on nuclear targets using photon beams from the STB Tagger with SCISSORS.Excitation functions of the cross sections of (γ, η) reactions were decuced with much better statistics. The data are being analyzed now.(6) We have developed a solid hydrogen target in order to measure the H(γ, η) reaction, and succeeded to make a large volume of solid hydrogen, such as 30mm x 30mm x 40mm.

(1)分析了在INS电子同步辐射装置上获得的C，Al，Cu（γ，η）反应的实验数据，推导出的反应截面首次显示出宽共振结构，峰值在900 MeV附近。结果表明，该共振对应于核中S_（1535）共振的激发和衰变<11>。(2)本文用量子分子动力学模型计算了（γ，η）反应的截面。将实验数据与计算结果进行了比较，并提出了核介质中S_（11）共振比真空中宽的可能性。然而，为了得出明确的结论，还需要进行大量的实验工作，以获得更准确的详细数据。(3)我们已经在东北大学核科学实验室建造了STB标记器，它可以从STB环中产生GeV质量良好的标记光子。(4)为了更有效地测量η介子，我们设计并实现了一个由200多个CsI探测器组成的多探测器系统SCISSORS。(5)用STB-Tagger的光子束测量了核靶上的η光生反应，得到了（γ，η）反应截面的激发函数，具有较好的统计性。数据正在分析中。(6)我们研制了一种用于测量H（γ，η）反应的固体氢靶，并成功地制作了30 mm × 30 mm × 40 mm的大体积固体氢靶。