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arXiv 0901.2985nucl-thnucl-ex
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具有Skyrme有效相互作用的统计多重碎裂模型

The Statistical Multifragmentation Model with Skyrme Effective Interactions

S. R. Souza, B. V. Carlson, R. Donangelo, W. G. Lynch, A. W. Steiner, M. B. Tsang

摘要:

对统计多重碎裂模型进行了修正,使之与有限温度下Skyrme有效相互作用下计算的Helmholtz自由能相结合。在这个公式中,处于冻结构型的碎片的密度对应于在给定温度下在费米子-费米近似中获得的平衡值。在微正则系综中研究了定体积核热量曲线的行为,发现激发能在8 - 10 MeV/核子之间有一个平台。一个扭结的热量曲线被发现在这个气体转变的发病,表明存在一个小的激发能区域的负热容。与以前的统计计算相反,即使在系统被限制为固定体积的情况下,这种情况也会发生。观察到的相变发生在近似恒定的熵。电荷分布和其他可观测量在有限温度下,特别是在高激发能下,对自由能和碎片体积的计算中所采用的处理也很敏感。同位素分布也受到这种处理的影响,这表明这种处方可能有助于获得有关核物质状态方程的信息。

英文摘要:

The Statistical Multifragmentation Model is modified to incorporate the Helmholtz free energies calculated in the finite temperature Thomas-Fermi approximation using Skyrme effective interactions. In this formulation, the density of the fragments at the freeze-out configuration corresponds to the equilibrium value obtained in the Thomas-Fermi approximation at the given temperature. The behavior of the nuclear caloric curve at constant volume is investigated in the micro-canonical ensemble and a plateau is observed for excitation energies between 8 and 10 MeV per nucleon. A kink in the caloric curve is found at the onset of this gas transition, indicating the existence of a small excitation energy region with negative heat capacity. In contrast to previous statistical calculations, this situation takes place even in this case in which the system is constrained to fixed volume. The observed phase transition takes place at approximately constant entropy. The charge distribution and other observables also turn out to be sensitive to the treatment employed in the calculation of the free energies and the fragments' volumes at finite temperature, specially at high excitation energies. The isotopic distribution is also affected by this treatment, which suggests that this prescription may help to obtain information on the nuclear equation of state.

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。

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