Programme

P.10 -- Poster, VCTP-47

Date: Tuesday, 2 August 2022

Time: 08:30 - 10:00

Proton entropy excess and possible signature of pairing reentrance in hot nuclei

Balaram Dey (1), Srijit Bhattacharya (2), Deepak Pandit (3), N. Dinh Dang (4), N. Ngoc Anh (5), L. Tan Phuc (6,7), N. Quang Hung (6,7)

(1) Department of Physics, Bankura University, Bankura, West Bengal-722155, India (2) Department of Physics, Barasat Govt. College, Barasat, N 24 Pgs, Kolkata-700124, India (3) Variable Energy Cyclotron Centre, 1/AF-Bidhannagar, Kolkata-700064, India d Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, India (4) Quantum Hadron Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science, 2-1 Hirosawa, Wako City, 351-0198 Saitama, Japan (5) Dalat Nuclear Research Institute, Vietnam Atomic Energy Institute, 01 Nguyen Tu Luc, Dalat City 670000, Viet Nam (6) Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City 700000, Viet Nam (7) Faculty of Natural Sciences, Duy Tan University, Da Nang City 550000, Viet Nam

In this work, we investigated the entropy excess caused by one proton (the so-called proton entropy excess) for several pairs of medium and heavy mass nuclei using the available nuclear level density data. Results obtained show that the proton entropy excess as a function of excitation energy E* can be well described by the recent microscopic calculations based on the exact pairing plus independent-particle model at finite temperature (EP+IPM). It is also observed that the proton entropy excess is ~0.1−0.5 kB for the spherical nuclei and ~1.0−1.2 kB for the deformed ones. These values are notably smaller than those obtained from the neutron entropy excess (~1.3−2.0 kB). This is due to the effect of Coulomb interaction as well as the proton single-particle level densities, which is less than the neutron ones. In particular, we observed a peak-like structure in the proton entropy excess at low E*<1 MeV. This structure is possibly associated with the pairing reentrance phenomenon caused by the weakening of blocking effect in odd nuclei at low temperature as explained by the EP+IPM. This peak-like structure is more pronounced in the spherical nuclei than in the deformed isotopes [1].
Reference:
[1] Balaram Dey, Srijit Bhattacharya, Deepak Pandit, N. Dinh Dang, N. Ngoc Anh, L. Tan Phuc, and N. Quang Hung, Phys. Lett. B 819, 136445 (2021).

Presenter: Nguyen Quang Hung