KEWPIE2: A Cascade Code for the Study of Dynamical Decay of Excited Nuclei

KEWPIE–a cascade code devoted to investigating the dynamical decay of excited nuclei, specially designed for treating very low probability events related to the synthesis of super-heavy nuclei formed in fusion–evaporation reactions–has been improved and rewritten in C++ programming language to become KEWPIE2. The current version of the code comprises various nuclear models concerning the light-particle emission, fission process and statistical properties of excited nuclei. General features of the code, such as the numerical scheme and the main physical ingredients, are described in detail. Some typical calculations having been performed in the present paper clearly show that theoretical predictions are generally in accordance with experimental data. Furthermore, since the values of some input parameters cannot be determined neither theoretically nor experimentally, a sensibility analysis is presented. To this end, we systematically investigate the effects of using different parameter values and reaction models on the final results. As expected, in the case of heavy nuclei, the fission process has the most crucial role to play in theoretical predictions. This work would be essential for numerical modeling of fusion–evaporation reactions.

KEWPIE（KEWPIE）是一款用于研究激发态原子核动力学衰变的级联代码，其专为处理熔合蒸发反应（fusion–evaporation reactions）中生成超重原子核（super-heavy nuclei）相关的极低概率事件而设计。该代码已完成改进并以C++编程语言重写，新版本命名为KEWPIE2。当前版本的代码包含多种核物理模型，可用于描述轻粒子发射、裂变过程以及激发态原子核的统计特性。本文详细阐述了该代码的通用特性，包括数值方案与核心物理组分。本文中开展的若干典型计算结果清晰表明，理论预测与实验数据整体吻合良好。此外，由于部分输入参数的取值既无法通过理论途径也无法通过实验途径确定，本文开展了敏感性分析。为此，本文系统研究了采用不同参数取值与反应模型对最终计算结果的影响。正如预期，对于重原子核而言，裂变过程在理论预测中起到最为关键的作用。本研究对于熔合蒸发反应的数值模拟具有重要意义。