arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1506.04844nucl-th
收藏

用约束分子动力学(CoMD)模型描述质子诱导fission的微观动力学

Microscopic dynamical description of proton-induced fission with the Constrained Molecular Dynamics (CoMD) Model

N. Vonta, G. A. Souliotis, M. Veselsky, A. Bonasera

摘要:

核裂变的微观描述仍然是一个紧张的基础研究课题。了解核裂变,除了从理论的角度来看,是具有实际意义的能源生产和核废料的嬗变。在核天体物理学中,裂变为重元素通过r过程的核合成设定了上限。在这项工作中,我们使用约束分子动力学(CoMD)程序对中能质子诱发裂变进行了系统的研究。CoMD代码实现了一个有效的相互作用与核物质的压缩系数K=200(软状态方程)与几种形式的密度依赖的核子-核子对称势。此外,在碰撞的每个时间步,对每个核子的相空间占据施加了一个约束,恢复了泡利原理。对描述裂变的有效相互作用的表面参数进行了适当的选择。在这项工作中,我们提出的裂变计算结果的质子诱导反应:a)232 Th在27和63 MeV,b)235 U在10,30,60和100 MeV,和c)238 U在100和660 MeV。计算的观测量包括裂变碎片的质量分布,总裂变能量,中子多重性和裂变时间。这些观测值进行了比较,现有的实验数据。我们表明,微观CoMD代码是能够描述复杂的多体动力学的裂变过程中,高能量,并给出了一个合理的估计裂变的时间尺度。灵敏度的结果的密度依赖的核子对称性势(和,因此,核的对称性能源)的found. Further改进的代码是必要的,以实现一个令人满意的描述低能量裂变壳效应起主导作用。

英文摘要:

The microscopic description of nuclear fission still remains a topic of intense basic research. Un- derstanding nuclear fission, apart from a theoretical point of view, is of practical importance for energy production and the transmutation of nuclear waste. In nuclear astrophysics, fission sets the upper limit to the nucleosynthesis of heavy elements via the r-process. In this work we initiated a systematic study of intermediate energy proton-induced fission using the Constrained Molecu- lar Dynamics (CoMD) code. The CoMD code implements an effective interaction with a nuclear matter compressibility of K=200 (soft EOS) with several forms of the density dependence of the nucleon-nucleon symmetry potential. Moreover, a constraint is imposed in the phase-space occu- pation for each nucleon restoring the Pauli principle at each time step of the collision. A proper choice of the surface parameter of the effective interaction has been made to describe fission. In this work, we present results of fission calculations for proton-induced reactions on : a) 232 Th at 27 and 63 MeV, b) 235 U at 10, 30, 60 and 100 MeV, and c) 238 U at 100 and 660 MeV. The calculated observables include fission-fragment mass distributions, total fission energies, neutron multiplicities and fission times. These observables are compared to available experimental data. We show that the microscopic CoMD code is able to describe the complicated many-body dynamics of the fission process at intermediate and high energy and give a reasonable estimate of the fission time scale. Sensitivity of the results to the density dependence of the nucleon symmetry potential (and, thus, the nuclear symmetry energy) is found. Further improvements of the code are necessary to achieve a satisfactory description of low energy fission in which shell effects play a dominant role.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑