35MeV/u^(40)Ar+^(197)Au中的熵产生  

ENTROPY PRODUCED IN 35MeV/u ~ (40)Ar+ ^(197 ) Au HEAVY ION REACTIONS

作　　者：魏志勇[1] 段利敏[1] 吴和宇[1] 靳根明[1] 李祖玉[1] 诸永泰[1] 郗洪飞[1] 沈文庆[2] 肖志刚[1] 王宏伟[1] 张保国[1] 柳永英[1] 王素芳[1] 胡荣江[1] 

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]中国科学院上海原子核研究所,上海201800

出　　处：《物理学报》2001年第4期649-654,共6页Acta Physica Sinica

基　　金：中国科学院归国学者基金;国家自然科学基金 !(批准号 :10 0 2 195 0 5 0 0 7;10 0 2 19675 0 5 3 );中国科学院九五重点项目研究基金

摘　　要：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+3 He+4 He)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/u4 0 Ar +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Breakup密度接近但小于 0 1(ρ/ ρ0 )Light charged particles emitted from the reactions of 35MeV/u 40 Ar+ 197 Au 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/ρ 0 ) 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/ρ 0 ).

关 键 词：熵 约化d产额 核温度 量子统计模型 核反应过程 重离子碰撞 

分 类 号：O572[理学—粒子物理与原子核物理]