Programme

O.8 -- Oral, VCTP-44

Date: Monday, 29 July 2019

Time: 17:10 - 17:30

Second-order phase transition in an odd-odd deformed and hot-rotating nucleus

Nguyen Quang Hung

Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City, Viet Nam

The thermodynamic properties of $^{200}$Tl, $^{211}$Po, and $^{212}$At nuclei are studied by using the angular-momentum gated nuclear level densities (NLDs) extracted from the experimental particle evaporation spectra in the excitation energy range of 2-15 MeV. The experimental NLDs are found in very good agreement with the results of the exact pairing plus the independent-particle model at finite temperature (EP+IPM) [1]. Consequently, the heat capacities of the above nuclei at finite angular momentum have been extracted using the EP+IPM NLDs. The results obtained show that while the heat capacities of $^{200}$Tl, $^{211}Po, and $^{212}$At (near spherical nuclei) follow the trend as expected in odd–odd and even–odd masses, surprisingly an $S$-shaped heat capacity, which is the signature of the superfluid-to-normal (second-order) phase transition, is found in an odd–odd deformed nucleus $^{184}$Re. This $S$-shaped heat capacity observed in $^{184}$Re is microscopically explained by not only the breaking of nucleon Cooper pairs but also the change of pairing induced by deformation within the EP+IPM [2]. References [1] N. Quang Hung, N. Dinh Dang, and L. T. Quynh Huong, Phys. Rev. Lett. 118, 022502 (2017). [2] Balaram Dey, N. Quang Hung, Deepak Pandit, Srijit Bhattacharya, N. Dinh Dang, L. T. Quynh Huong, Debasish Mondal, S. Mukhopadhyay, Surajit Pal, A. De, and S. R. Banerjee, Phys. Lett. B 789, 634 (2019).

Presenter: Nguyen Quang Hung