Programme

P.59 -- Poster, VCTP-49

Date: Friday, 2 August 2024

Time: 08:30 - 10:00

Exploring Empirical Thermodynamic Quantities of Excited Nuclei Through Canonical Ensemble

Nguyen Ngoc Anh (1,2), Tran Vu Dong (3,4), Phan Nhat Huan (3,4), Nguyen Quang Hung (3,4), Nguyen Xuan Hai (5), Le Thi Quynh Huong (6)

(1) Phenikaa Institute of Advanced Study, PHENIKAA University, Yen Nghia, Ha Dong, Hanoi 12116, Vietnam (2) Faculty of Fundamental Science, PHENIKAA University, Yen Nghia, Ha Dong, Hanoi 12116, Vietnam (3) Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City 70000, Vietnam (4) Faculty of Natural Sciences, Duy Tan University, Danang City 50000, Vietnam (5) Dalat Nuclear Research Institute, Vietnam Atomic Energy Institute, Dalat City 670000, Vietnam (6) Department of Natural Science and Technology, University of Khanh Hoa, Nha Trang City, Khanh Hoa Province, Vietnam

Thermodynamic quantities (TQs), including the free energy, entropy, total energy, and heat capacity of excited nuclei, play important roles, as they not only contribute to clarifying the structure and properties of atomic nuclei but also serve as a connection between the microscopic realm and macroscopic domains, e.g., from the tiny world of nucleons to infinite nuclear matters. From the experimental nuclear level density (NLD) data at the excitation energy below the neutron binding energy and the back-shifted Fermi gas NLD model, we have derived semi-empirical TQs of 78 nuclei, whose mass number ranges from 43 to 243, using the canonical ensemble. The obtained results reveal four systematic conclusions, as follows: (1) The free energy of even-even nuclei exhibits distinct behavior as compared to that of odd-A ones; (2) The variation of total energy with respect to nuclear temperature demonstrates the constant temperature characteristic of nuclei at low-excitation energies; (3) The entropy undergoes sudden changes at critical temperatures of approximately 0.3 and 0.55 MeV for medium- and heavy-mass nuclei, respectively. These changes are interpreted as the break of the first Cooper pair; (4) Pronounced S-shapes are seen in the heat capacities of nuclei of rare-earth elements. In addition, the temperatures defined at the center of these S-shapes are pretty close to theoretical predictions for the critical temperature of pairing phase transition. These results have been published in [J. Phys. G: Nucl. Part. Phys. 51 (2024) 065105].

Presenter: Nguyen Ngoc Anh