摘要:
为了研究曲率能对核裂变热力学驱动力(TDF) 的影响,首先利用包含曲率能的截断版小液滴模型计算了200Pb 和224Th 的位垒和熵垒,对比液滴模型的计算结果表明:曲率能未改变224Th 的位垒鞍点,却将200Pb 的位垒鞍点向后推移.能级密度参数的形变关系越强则两系统的熵垒鞍点越靠近基态.为了进一步探究曲率能如何通过位势和熵势影响TDF,以断前中子多重性(PNM) 为探针,通过两种方案进行了模拟,结果表明:曲率能降低了两系统的位势驱动力,而增强了其熵势驱动力.结合PNM的计算表明,前一种效应要比后一种效应明显,因此曲率能总体减弱了200Pb 和224Th 的TDF,进而延缓了两系统的核裂变进程.
Abstract:
In order to study the effect of curvature energy on the thermodynamic driving force (TDF) of nuclear fission, the potential and entropy barrier of 200Pb and 224Th systems are calculated by using the truncated droplet model including curvature energy, respectively. Compared with the liquid drop model, the results show that curvature energy does not affect the saddle point of 224Th , but pushes the saddle point of 200Pb backwards the ground state. The stronger the deformation dependence of the level density parameter is, the closer the saddle point of entropy barrier for these systems is to the ground state. In order to further investigate how curvature energy affects TDF through nuclear potential and entropy, respectively, the prescission neutron multiplicity (PNM) is selected as the probe, some simulations based on two schemes are carried out. The results show that curvature energy reduces the potential driving force of 200Pb and 224Th , and enhances the entropy potential driving force. Combined with the calculations and analyses of PNM, the former effect is more obvious than the latter, so curvature energy weakens TDF of two systems on whole, thus delaying the nuclear fission process of two systems.
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