Research on nuclear thermodynamical properties via microscopic theories and applications to nuclear astrophysics

微观理论研究核热力学性质及其在核天体物理中的应用

基本信息

批准号：
15340070
负责人：
NAKADA Hitoshi
金额：
$ 8.7万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

We have studied thermodynamical properties of atomic nuclei and related topics, and have obtained the following results.1. We have developed a convenient technique of angular-momentum projection in the shell model Monte Carlo method, and have applied it to investigate spin-dependence of nuclear level densities. By numerical calculations on Fe-Ni nuclei, we have found that the pair correlation influences low-energy densities of even-even nuclei, which disappears as the energies goes higher, and that such effects are not viewed in odd nuclei.2. We have implemented calculation of level densities of well-deformed nuclei in the rare-earth region, such as ^<162>Dy, and succeeded in reproducing experimental data in wide energy region.3. We have reformulated quantum-number projection in finite-temperature mean-field theories, and moreover, have formulated a BCS-type theory in canonical ensembles for the first time. These have been applied to investigate role of conservation laws in phase transition in finite systems for increasing temperature, the superfluid-to-normal transition in particular. We have pointed out that the S-shape heat capacity of nuclei, which had been suggested to be a fingerprint of the superfluid-to-normal transition, comes out because of the particle-number conservation.4. We have developed a new algorithm for Hartree-Fock-Bogolyubov calculations by applying the Gaussian expansion method, in order to investigate shell structure in unstable nuclei and effects of the pairing correlation. Shell structure around the new magic numbers N=16 and 32 depends on effective interactions. However, the shell gap is almost compensated by the pairing gap in the HFB calculations.

我们研究了原子核和相关主题的热力学特性，并获得了以下结果。1。我们已经在壳模型蒙特卡洛法中开发了一种方便的角度摩托明投影技术，并将其应用于研究核水平密度的自旋依赖性。通过对Fe-Ni核的数值计算，我们发现，这对相关性会影响均匀核的低能密度，随着能量越高而消失，并且在奇数Nuclei.2中没有观察到这种效果。我们已经实施了在稀土区（例如 ^<162> dy）中良好形成核的水平密度的计算，并成功地重现了广泛的能量区域的实验数据。3。我们已经在有限温度的平均场理论中重新重新制定了量子数投影，此外，我们首次在规范集合中提出了BCS型理论。这些已应用于研究保护定律在有限系统中的相变中的作用，以提高温度，尤其是超氟到正常的过渡。我们已经指出，由于粒子数量的保护，核的S形热容量被认为是超流体到正常过渡的指纹。4。我们通过应用高斯膨胀方法开发了一种用于Hartree-Fock-Bogolyubov计算的新算法，以研究不稳定核中的壳结构和配对相关的影响。围绕新魔术数n = 16和32的壳结构取决于有效的相互作用。但是，在HFB计算中的配对差距几乎可以补偿壳体间隙。