Programme

O.13 -- Oral, VCTP-45

Date: Tuesday, 13 October 2020

Time: 16:00 - 16:20

A fully microscopic model of total level density in spherical nuclei: an example of $^{60}$Ni nucleus

Nguyen Quang Hung (1,2), Nguyen Dinh Dang (3), Le Tan Phuc (1,2), Nguyen Ngoc Anh (4), Tran Dong Xuan (1,2), and Tran Viet Nhan Hao (5)

(1) Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City, Viet Nam; (2) Faculty of Natural Sciences, Duy Tan University, Da Nang City, Viet Nam; (3) Quantum Hadron Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science, 2-1 Hirosawa, Wako City, Saitama, Japan; (4) Da Lat Nucear Research Institute, Vietnam Atomic Energy Institute, 01 Nguyen Tu Luc, Da Lat City, Viet Nam; (5) Faculty of Physics, University of Education, Hue University, 34 Le Loi, Hue City, Viet Nam

A fully microscopic model for the description of nuclear level density (NLD) in spherical nuclei is proposed. The model is derived by combining the partition function of the exact pairing solution plus the independent-particle model at finite temperature (EP+IPM) [1] with that obtained by using the collective vibrational states calculated from the self-consistent Hartree-Fock mean field with MSk3 interaction plus the exact pairing and random-phase approximation (SC-HFEPRPA) [2]. For the first time, two important factors are taken into account in a fully microscopic way, namely the spin cut-off and vibrational enhancement factors are, respectively, calculated using the statistical thermodynamics and partition function of the SC-HFEPRPA without any fitting parameters. The numerical test for a spherical $^{60}$Ni nucleus, the only nucleus whose experimental NLD data are presently available from 0 to about 23 MeV of excitation energy, shows that the collective vibrational enhancement is mostly dominated by the quadrupole and octupole excitations. This is the first microscopic model confirming such an effect, which was phenomenologically predicted long time ago and widely employed in several NLD models. In addition, the influence of collective vibrational enhancement on nuclear thermodynamic quantities such as excitation energy, specific heat capacity and entropy is also studied by using the proposed model [3]. References: [1] N. Quang Hung, N. Dinh Dang, and L. T. Quynh Huong, Phys. Rev. Lett. 118, 022502 (2017). [2] L. Tan Phuc, N. Quang Hung, and N. Dinh Dang, Phys. Rev. C 99, 064322 (2019). [3] N. Quang Hung, N. Dinh Dang, L. Tan Phuc, N. Ngoc Anh, T. Dong Xuan, and T. V. Nhan Hao, Phys. Lett. B (submitted) (Jan. 2020).

Presenter: Nguyễn Quang Hưng