Fission dynamics within time-dependent Hartree-Fock. II. Boost-induced fission
Fission dynamics within time-dependent Hartree-Fock. II. Boost-induced fission
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DOI：
10.1103/physrevc.93.014620
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发表时间：
2015-10
影响因子：
3.1
通讯作者：
Philip Goddard;Paul Stevenson;Arnau Rios
中科院分区：
文献类型：
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作者：
Philip Goddard;Paul Stevenson;Arnau Rios
背景：核裂变是重核中一种复杂的大幅度集体衰变模式。以前对裂变的微观密度泛函研究主要集中在基于有约束的静态计算的绝热方法上，忽略了裂变核及其子产物的动力学激发。目的：以核素240Pu中的四极助推为例，探讨动态平均场方法描述诱发裂变过程的能力。方法：遵循Goddard等人提出的工作。[物理。Rev.C 92,054610(2015年)]，使用四极约束的Hartree-Fock计算来创建势能面。通过四极形的瞬时规范跃迁和时间延展规范激发，激发了一个同质异构态和一个超过第二势垒峰的态。随后的退激在含时的Hartree-Fock模拟中进行了研究，重点是裂变的终态。研究了相应的裂变碎片质量数。结果：一般情况下，四极助推所沉积的能量会被原子核迅速吸收。在瞬间的助推中，这会导致快速的形状重排和剧烈的动力学，最终可能导致裂变。这是一个与形变引起的裂变本质上不同的过程。在有限时间窗内诱导的助推以一种相对温和的方式激发系统，并确实引发裂变，但能量沉积较小。结论：在含时Hartree-Fock模型中，用Boost诱发裂变得到的裂变产物比形变诱发裂变或相应的绝热方法得到的碎片更不对称。
Background: Nuclear fission is a complex large-amplitude collective decay mode in heavy nuclei. Microscopic density functional studies of fission have previously concentrated on adiabatic approaches based on constrained static calculations ignoring dynamical excitations of the fissioning nucleus and the daughter products. Purpose: We explore the ability of dynamic mean-field methods to describe induced fission processes, using quadrupole boosts in the nuclide 240Pu as an example. Methods: Following upon the work presented in Goddard et al. [Phys. Rev. C 92, 054610 (2015)], quadrupoleconstrained Hartree-Fock calculations are used to create a potential energy surface. An isomeric state and a state beyond the second barrier peak are excited by means of instantaneous as well as temporally extended gauge boosts with quadrupole shapes. The subsequent deexcitation is studied in a time-dependent Hartree-Fock simulation, with emphasis on fissioned final states. The corresponding fission fragment mass numbers are studied. Results: In general, the energy deposited by the quadrupole boost is quickly absorbed by the nucleus. In instantaneous boosts, this leads to fast shape rearrangements and violent dynamics that can ultimately lead to fission. This is a qualitatively different process than the deformation-induced fission. Boosts induced within a finite time window excite the system in a relatively gentler way and do induce fission but with a smaller energy deposition. Conclusions: The fission products obtained using boost-induced fission in time-dependent Hartree-Fock are more asymmetric than the fragments obtained in deformation-induced fission or the corresponding adiabatic approaches.