论文部分内容阅读
用推广的裂变扩散模型研究了2 8Si+16 4,16 7,170 Er→192 ,195,198Pb反应中测量的断前中子、质子和α粒子多重性的激发函数 .发现扩散模型能很好地拟合这些轻粒子多重性随裂变系统激发能和Pb同位素的变化趋势 .表明断前粒子发射存在一个同位素效应 .进而在一个考虑了裂变过程中摩擦效应的统计模型的框架内 ,在In和Er这两个元素的同位素链中 ,考察了同位素效应与裂变碎片质量不对称性和裂变系统尺度的关系 .计算结果表明 :同位素效应的存在不依赖于裂变系统的大小和不对称性 .此外 ,当裂变系统具有高的中质比时 ,轻带电粒子发射将不再敏感于裂变延迟时间的长短 ,而中子发射则非常敏感 .这个结果暗示对那些特别丰中子的裂变系统 ,轻带电粒子 (质子和α粒子 )的多重性对于研究热核裂变过程中的摩擦强度不是一个好的探针 .
Using the extended fission diffusion model, the multiplicative excitation functions of neutrons, protons and α particles measured in the reaction of 2 8 Si + 16 4, 16 7, 170 Er → 192, 195 and 198Pb were studied. The diffusion model was found to fit well The multiplicity of these light particles varies with the variation of the excitation energy and Pb isotope of the fission system, indicating that there is an isotopic effect on the emission of the pre-fault particles. In the framework of a statistical model that considers the friction effect in the fission process, The relationship between the isotope effect and the mass asymmetry of fission fragments and the fission system scale is investigated.The results show that the existence of isotope effect does not depend on the size and asymmetry of the fission system.In addition, With high mass-to-mass ratio, light-charged particle emission will no longer be sensitive to the length of the fission delay, while neutron emission is very sensitive, suggesting that for those fossil-rich neutron fission systems, light charged particles (proton and α particle) is not a good probe for the study of the frictional intensity in the thermonuclear fission process.