Speaker
Description
Electric (E1) and magnetic (M1) dipole modes are key contributors to γ-ray strength functions, directly influencing reaction rates relevant to stellar evolution and rapid neutron-capture (r-process) nucleosynthesis. Understanding electromagnetic excitations in atomic nuclei under extreme conditions, including finite temperature, is therefore crucial for advancing nuclear structure theory and astrophysical modeling. Owing to the limited experimental accessibility of hot nuclei, robust microscopic theoretical frameworks are essential.
In this contribution, I present a unified microscopic analysis of E1 and M1 strength distributions using the finite-temperature relativistic quasiparticle random-phase approximation (FT-RQRPA), formulated within covariant energy density functional theory with point-coupling interactions. Particular emphasis is placed on thermal unblocking mechanisms and their influence on low-energy dipole excitations. I first discuss predictions for neutron-rich nickel isotopes, where increasing temperature leads to a pronounced enhancement of low-energy E1 strength, identified as hot pygmy dipole strength. This behaviour arises from thermally activated quasiparticle configurations and provides valuable theoretical guidance for current and future experimental efforts [1,2]. I then examine the temperature evolution of γ-ray strength functions, showing how both E1 and M1 components are progressively reshaped as thermal effects become significant [3]. These results underscore the strong temperature dependence of the electromagnetic response and provide essential microscopic input for r-process network calculations and nuclear data evaluations in hot astrophysical environments.
References:
[1] A. Kaur, E. Yüksel, and N. Paar, Phys. Rev. C 112, L051304 (2025).
[2] O. Wieland et al., Acta Physica Polonica B Proceedings Supplement 18, 2-A33, (2025).
[3] A. Kaur, E. Yüksel, and N. Paar, Physical Review C 112, 014307 (2025).
| Contribution category | Theory |
|---|---|
| Presenter status | Faculty/Staff |