The thermodynamic model for nuclear multifragmentation
The thermodynamic model for nuclear multifragmentation
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DOI：
10.1016/j.physrep.2004.10.002
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发表时间：
2004-10
期刊：
影响因子：
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通讯作者：
C.B.Das;S.Das Gupta;W.G.Lynch;A.Z.Mekjian;M.B.Tsang
中科院分区：
文献类型：
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作者：
C.B.Das;S.Das Gupta;W.G.Lynch;A.Z.Mekjian;M.B.Tsang
在中能重离子碰撞中观察到的许多可观测现象可以根据统计平衡来解释。基于统计平衡的计算可以在微正则系综（系统中的能量和粒子数量保持固定）、正则系综（温度和粒子数量保持固定）或大正则系综（固定温度和可变粒子数但具有指定平均值）中实现。本文涉及规范系综的计算。最近开发的递归关系允许对许多核问题进行任意精度的计算。计算研究中能重离子碰撞中相变的性质，研究原子核的热量曲线，并探讨由于核系统的有限性而产生负比热的可能性。该模型还可用于与相变无关的其他可观测值的详细计算，例如重离子碰撞中选定同位素的种群。该模型还具有教学目的。对于当前的问题，正则解和大正则解都可以任意精度获得，因此我们可以将从正则计算中获得的可观测量值与从大正则计算中获得的可观测量值进行比较。有时，会发现非常有趣的差异。为了说明模型的预测能力，将计算的可观测值与锡同位素中心碰撞的数据进行了比较。
A great many observables seen in intermediate energy heavy ion collisions can be explained on the basis of statistical equilibrium. Calculations based on statistical equilibrium can be implemented in microcanonical ensemble (energy and number of particles in the system are kept fixed), canonical ensemble (temperature and number of particles are kept fixed) or grand canonical ensemble (fixed temperature and a variable number of particles but with an assigned average). This paper deals with calculations with canonical ensembles. A recursive relation developed recently allows calculations with arbitrary precision for many nuclear problems. Calculations are done to study the nature of phase transition in intermediate energy heavy ion collision, to study the caloric curves for nuclei and to explore the possibility of negative specific heat because of the finiteness of nuclear systems. The model can also be used for detailed calculations of other observables not connected with phase transitions, such as populations of selected isotopes in a heavy ion collision. The model also serves a pedagogical purpose. For the problems at hand, both the canonical and grand canonical solutions are obtainable with arbitrary accuracy hence we can compare the values of observables obtained from the canonical calculations with those from the grand canonical. Sometimes, very interesting discrepancies are found. To illustrate the predictive power of the model, calculated observables are compared with data from the central collisions of Sn isotopes.