Study of Giant resonances in Hot Nuclei produced in Heavy Ion Fusion Reactions

重离子聚变反应产生的热核的巨共振研究

基本信息

批准号：
02640219
负责人：
KASAGI Jirohta
金额：
$ 1.79万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02640219/
关键词：
Giant Resonance Hot Nuclei Heavy Ion Reaction Fusion Reaction High Energy gamma rays Level Density Limiting Temperature Statistical Model γ線多重度

项目摘要

1. We have studied properties of hot nuclei by using ^<40>Ar+Ni, ^<92>Mo, and ^<122>Sn reactions with E/A=21 and 26 MeV by using the RIKEN Ring Cyclotron. Fusion reaction process was selected to study level densities and giant dipole resonances in hot nuclei. It was found that neutron energy spectra measured in coincidence with fusion residues were reproduced with the level density parameter a=A/(9<plus-minus>1). However, yields of the GDR decay gamma rays do not increase above E_x-250 MeV. The limiting temperature for the GDR gamma -ray decay were deduced as T_c-17A^<-1/3> for 80 < A < 150. It is highly desirable to continue the systematic study in order to answer the question whether the collective motion of the nucleus disappears at the high temperature or the hot nucleus is cooled down by particle evaporations before it emitts gamma rays.2. In order to investigate the dependence of giant dipole resonances on the excitation energy and the angular momentum, high energy gamma rays were measured in ^<100>Mo+^<32>S reaction with E=150, 180 and 210 MeV using the tandem accelerator at JAERI. The result shows that the GDR width depends strongly on the thermal excitation energy for E_x > 100 MeV and an empirical formula GAMMA =4.5+0.035E_x+1.6x10^<-8>E_x^4 obtained in the previous work at RIKEN can explain the data very well.

1。我们使用 ^<40> ar+ni， ^<92> mo和 ^<122> Sn反应与E/A = 21和26 MeV研究了热核的性质，并使用Riken Ring Cyclotron。选择融合反应过程以研究热核中的水平密度和巨大的偶极共振。发现与融合残基一起测量的中子能光谱与水平密度参数a = a = a/（9 <plus-minus> 1）复合。但是，GDR Decay伽马射线的产量不会超过E_X-250 MEV。将GDRγ-雷衰变的限制温度推定为T_C-17A^<-1/3> 80 <a <150。继续进行系统的研究，以回答核的集体运动在高温下消失的问题是高温还是由粒子蒸发降低的问题是在其emitts emitts gama rays.2上被粒子蒸发冷却。为了研究巨型偶极子共振对激发能和角动量的依赖性，使用Jaeri的串联加速器在Jaeri的tandem加速器中测量了与E = 150、180和210 MEV的 ^<100> MO+ ^<32> S以E = 150、180和210 MEV的反应测量。结果表明，GDR宽度在很大程度上取决于E_X> 100 MEV的热激发能和经验公式伽玛= 4.5+0.035e_x+1.6x10^<-8> E_X^4在Riken的先前工作中获得的E_X^4可以很好地解释数据。