核破裂中的粒子发射和临界涨落

PARTICLE EMISSION AND CRITICAL FLUCTUATION IN NUCLEAR DISASSEMBLY 

用晶格气体模型系统地研究了１２９ Ｘｅ 热发射体的轻粒子、带电粒子和中间质量碎片的发射特性，发现了在温度５ —５５ Ｍｅ Ｖ 区间，以上物理量的平均多重性和发射源的最大碎片余核及源的热激发能随温度变化的斜率存在着各自的峰值，同时它们的分布宽度（ 即涨落） 也存在着最大值．进一步研究发现在５ —５５ Ｍｅ Ｖ 区间，这些宽度随温度的变化的斜率显示了明显的不连续性．所有这些特征说明了在５ —５５ Ｍｅ Ｖ 的拐点温度处，最大的临界涨落是自发地伴随着相变和临界现象．

The emission of light particles(LP), charged particles(CP),intermediate mass fragments(IMF) and the largest fragment(MAX) for 129 Xe is investigated in the frame of lattice gas model.Definite turning points for the slopes of average multiplicity of LP,CP and IMF,mean mass of the largest fragment( A max ) and mean excitation energy per nucleon ( E\+*/A ) of the dissociation source against temperature are shown at 5—5 5?MeV,where the largest variances of the distributions of LP,CP,IMF,MAX and E\+*/A are observed also.Furthermore,the slopes of these variances with temperature show discontinuities at the same temperature.All these features indicate that the largest critical fluctuation is simultaneously accompanied by the critical phenomenon and phase transition at the turning temperature in the lattice gas model. PACC: 2570; 2587