25MeV/u^(40)Ar+^(93)Nb反应中热核巨共振研究  

The Study of Giant Dipole Resonance in Hot Nuclei in the 40Ar+93NbReaction at 25MeV/u

作　　者：张保国[1] 王素芳[1] 段利敏[1] 文万信[1] 靳根明[1] 郑纪文[1] 李祖玉[1] 贺智勇 肖志刚[1] 王宏伟[1] 

机构地区：[1]中国科学院近代物理研究所

出　　处：《高能物理与核物理》1998年第9期795-802,共8页High Energy Physics and Nuclear Physics

基　　金：国家自然科学基金

摘　　要：对２５ＭｅＶ／ｕ４０Ａｒ＋９３Ｎｂ反应形成的热核发射的γ射线、轻带电粒子和蒸发余核进行了符合测量，从余核的飞行时间和轻带电粒子能谱得出非完全熔合反应形成的热核的初始激发能．ＧＤＲγ衰变的产额在研究的激发能范围内保持不变。用统计模型ＣＡＳＣＡＤＥ程序对实验结果进行分析。讨论了引起ＧＤＲγ衰变产额饱和的原因。当假定热核激发能大于２５０ＭｅＶ时无ＧＤＲγ发射，则可以用ＣＡＳＣＡＤＥ程序很好地拟合Ｅγ大于１２ＭｅＶ的实验谱。Gamma rays, light charged particles and evaporation residues emitted from hot nuclei formed in the 40Ar +93Nb reaction at 25MeV / u have been measured.The initial excitation energies of the hot nuclei can be deduced from the velocity of the incomplete fusion residues by applying a massive transfer model. The integrated γ multiplicity, after bremsstrahlung substraction, is constant as a function of excitation Statistical calculations were performed by using the CASCADE code, and compared with experimental data. The main effects which can lead to the saturation of the GDR γmultiplicity at high excitation energies were discussed. The experimental data can be fitted by assuming a cutoff of γ emission from the resonance above an excitation energy of approximate 250MeV.

关 键 词：热核 激发能 GDR γ多重性饱和 巨共振 氩40 

分 类 号：O571.413[理学—粒子物理与原子核物理]