角动量对基于裂变截面探测核耗散的影响(英文)
Angular Momentum Effect on Probing Nuclear Dissipation with Fission Cross Section
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摘要: 核耗散降低了裂变截面值(σdropf )。基于Langevin 模型，研究了角动量对σdropf 作为鞍点前摩擦强度β 函数的影响。发现在低自旋，摩擦对σdropf的影响显著增强。通过考察系统195Bi，201Bi 和207Bi 的σdropf 随β 的演化，发现摩擦效应随着Bi 核中质比(N/Z) 的增加而变大。这些结果建议，为了更好地在实验上用裂变截面探测β，应产生那些具有低自旋、高N/Z 的热核系统。Using the Langevin model, we study the effect of angular momentum on the drop of fission cross sections caused by friction over its standard statistical-model value, σdropf as a function of presaddle friction strength β. It is found that friction effects on σdropf are substantially enhanced at low spin. In addition, by investigating the evolution of σdropf with β for 195Bi, 201Bi and 207Bi nuclei, we find that friction effects become greater with increasing the neutron-to-proton ratio (N/Z) of Bi nucleus. These results suggest that on the experimental side, to precisely probe presaddle dissipation by measuring fission excitation functions, it is best to yield excited nuclear systems with a small spin and a large N/Z.Abstract: Using the Langevin model, we study the effect of angular momentum on the drop of fission cross sections caused by friction over its standard statistical-model value, σdrop
f, as a function of presaddle friction strength β. It is found that friction effects on σdrop
f are substantially enhanced at low spin. In addition, by investigating the evolution of σdrop f with β for 195Bi, 201Bi and 207Bi nuclei, we find that friction effects become greater with increasing the neutron-to-proton ratio (N/Z) of Bi nucleus. These results suggest that on the experimental side, to precisely probe presaddle dissipation by measuring fission excitation functions, it is best to yield excited nuclear systems with a small spin and a large N/Z.
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