AI 中文总结
研究$^{235}$U(n,f)和$^{239}$Pu(n,f)反应中裂变核系统内禀形变影响，发现轨迹分三类，近对称裂变颈部拉长，影响碎片动能和激发能分布，还表征了颈部破裂对裂变中子发射的影响。
AI 中文摘要
本研究调查了裂变核系统在外鞍点附近的内禀形变对原子核从鞍点到裂变点的形状演化以及裂变碎片性质的影响。发现轨迹通常至少分为三类：不对称、近对称和高度不对称裂变，大致由八极矩的初始大小决定，每类都表现出不同的裂变动力学和碎片性质。近对称模式在裂变时导致高度拉长的颈部，使原碎片间距大于典型不对称裂变，导致总动能较低、总激发能较高，大部分额外激发能进入重裂变碎片使其产生显著四极形变。高度不对称裂变事件的总动能有类似趋势，而裂变碎片激发能趋势相反，大部分额外激发能进入轻裂变碎片。研究还对颈部破裂进行了表征，包括其对近对称裂变中裂变中子发射的影响。
英文摘要
This study investigates the consequences of the intrinsic deformation of the fissioning nuclear system near the outer saddle point on the shape evolution of the nucleus from saddle to scission and on the properties of the fission fragments. It is found that trajectories generally split into at least three classes, asymmetric, near-symmetric, and highly-asymmetric fission, that are roughly determined by the initial magnitude of the octupole moment, and each of which exhibits different scission dynamics and fragment properties. Near-symmetric modes result in a highly elongated neck at scission, leading to the neck rupture occurring when the proto-fragments are further apart than is the case for typical asymmetric fission, which in turn leads to a lower total kinetic energy and higher total excitation energy. The majority of this additional excitation energy goes into the heavy fission fragment, that develops a substantial quadrupole deformation. A similar trend is observed for the total kinetic energy of highly-asymmetric fission events, and the opposite trend for the excitation energy of the fission fragments as the majority of the additional excitation energy goes into the light fission fragment instead. The study also characterizes the neck rupture, including its effect on the emission of scission neutrons in near-symmetric fission.
Comments11 pages, 11 figures, 1 table
