35MeV/u40Ar+197Au中的熵产生

根据量子统计模型(QSM)的计算分析,找到了一个提取核反应过程中熵产生的新的可观测量.核反应过程中约化d的产额d/(d+t+³He+⁴He)和熵有单调的函数关系,并且和体系的碎裂密度(ρ/ρ₀)及体系的N/Z都无关,可以作为提取核反应过程中熵产生的一个观测量.和目前已经有的其他方法相比,约化d产额这一提取熵方法可以用于较低能量的重离子核反应中,并且数据处理分析简单.对于35MeV/u⁴⁰Ar+¹⁹⁷Au的核反应过程所提取的熵和利用约化带电粒子多重性提取的熵结果一致.结合后角类靶热核发射体系实验提取的同位素核温度为4.7±1.2MeV及S/A=2.5±0.5,根据熵和核温度的关联关系,可以确定其Break up密度接近但小于0.1(ρ/ρ₀)关键词：熵约化d产额核温度统计发射

ENTROPY PRODUCED IN 35MeV/u40Ar+197Au HEAVY ION REACTIONS

Light charged particles emitted from the reactions of 35MeV/u ⁴⁰Ar+¹⁹⁷Au are measured experimentally. A new observable,R=d/(d+t+³He+⁴He), which is defined as the reduced yield of deuterons, has a monotone relation with the entropy and it is independent of the breakup density (ρ/ρ₀) and N/Z of the system. The entropy values are extracted by using several methods which use the d/p ratios,d_like/p_like ratios, reduced yield of isotope deuterons R and the reduced multiplicity of charged particles M_red, respectively. The entropy values from the reduced yield of isotope deuterons R and the reduced multiplicity of charged particles M_red are nearly the same. These methods can be used in low beam energy heavy ion reactions. The charged particles emitted in rear angles are mainly from an equilibrium-state source with temperature about 4.7±1.2MeV, which are extracted from the double isotope yields ratios, and entropy S/A=2.5±0.5.This implies that the Break-up density is slightly less than 0.1(ρ/ρ₀).