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首页> 外文学位 >I. Excluded volume effects in Ising cluster distributions and nuclear multifragmentation. II. Multiple-chance effects in alpha-particle evaporation.
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I. Excluded volume effects in Ising cluster distributions and nuclear multifragmentation. II. Multiple-chance effects in alpha-particle evaporation.

机译：I.使用聚类分布和核多重破碎中排除的体积效应。二。 α粒子蒸发中的多机会效应。

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In Part I, geometric clusters of the Ising model are studied as possible model clusters for nuclear multifragmentation. These clusters may not be considered as non-interacting (ideal gas) due to excluded volume effect which predominantly is the artifact of the cluster's finite size. Interaction significantly complicates the use of clusters in the analysis of thermodynamic systems. Stillinger's theory is used as a basis for the analysis, which within the RFL (Reiss, Frisch, Lebowitz) fluid-of-spheres approximation produces a prediction for cluster concentrations well obeyed by geometric clusters of the Ising model. If thermodynamic condition of phase coexistence is met, these concentrations can be incorporated into a differential equation procedure of moderate complexity to elucidate the liquid-vapor phase diagram of the system with cluster interaction included. The drawback of increased complexity is outweighted by the reward of greater accuracy of the phase diagram, as it is demonstrated by the Ising model.; A novel nuclear-cluster analysis procedure is developed by modifying Fisher's model to contain cluster interaction and employing the differential equation procedure to obtain thermodynamic variables. With this procedure applied to geometric clusters, the guidelines are developed to look for excluded volume effect in nuclear multifragmentation.; In Part II, an explanation is offered for the recently observed oscillations in the energy spectra of alpha-particles emitted from hot compound nuclei. Contrary to what was previously expected, the oscillations are assumed to be caused by the multiple-chance nature of alpha-evaporation. In a semi-empirical fashion this assumption is successfully confirmed by a technique of two-spectra decomposition which treats experimental alpha-spectra as having contributions from at least two independent emitters.; Building upon the success of the multiple-chance explanation of the oscillations, Moretto's single-chance evaporation theory is augmented to include multiple-chance emission and tested on experimental data to yield positive results.
机译：在第一部分中，对Ising模型的几何聚类进行了研究，将其作为核多碎片化的可能模型聚类。由于排除了体积效应，这些团簇可能不被视为非相互作用（理想气体），而体积效应主要是团簇有限尺寸的伪影。相互作用使热力学系统分析中簇的使用大大复杂化。史蒂林格的理论被用作分析的基础，在RFL（Reiss，Frisch，Lebowitz）中，球体流体近似值可以预测出Ising模型的几何簇所能很好地满足的簇浓度。如果满足相共存的热力学条件，则可以将这些浓度合并到中等复杂度的微分方程程序中，以阐明包含团簇相互作用的系统的液-汽相图。正如伊辛模型所证明的那样，增加相图准确性的好处抵消了增加复杂性的缺点。通过修改费舍尔模型以包含团簇相互作用并采用微分方程法获得热力学变量，开发了一种新颖的核聚类分析程序。将此程序应用于几何簇时，制定了指南以寻找核多重碎片中排除的体积效应。在第二部分中，将对最近观察到的从热化合物核发射的α粒子的能谱振荡做出解释。与先前的预期相反，振荡被认为是由α蒸发的多机会性质引起的。以半经验的方式，该假设已通过两光谱分解技术得以成功证实，该技术将实验性α光谱视为至少具有两个独立发射体的贡献。基于对振荡的多机会解释的成功，Moretto的单机会蒸发理论得到了扩展，包括多机会发射，并在实验数据上进行了测试以得出肯定的结果。

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