2025/04/25 by Teruyuki Saito, Saito, Teruyuki, Masayuki Matsuo +1
Engineering · Physics and Astronomy · #FOS: Physical sciences #Nuclear Theory (nucl-th) #Nuclear physics research studies #Nuclear reactor physics and engineering #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2504.18239
openalex publication_date 2025/04/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We formulate a microscopic theory to calculate cross section of the radiative neutron capture on neutron-rich nuclei using the continuum quasiparticle random-phase approximation. This formulation is designed to be applied to neutron-rich nuclei around the r-process path, for which the compound nuclear model may not be appropriate. It takes into account effects of various excitation modes such as the soft dipole excitation, the giant resonances, and the quasiparticle resonance in addition to the surface vibrations such as quadrupole and octupole modes. We perform numerical calculations to demonstrate new features of the present theory, employing reactions 89\rm Ge(n,γ)90\rm Ge and 91\rm Zn(n,γ)92\rm Zn with E1 transitions populating the ground state, collective 2+1 and 3-1 states in 90\rm Ge and 92\rm Zn. With these examples, we discuss enhanced resonance contributions in the (n,γ) reaction at low energy, which originate from the quasiparticle resonance and the pygmy quadrupole resonance located just above the one neutron separation energy, and from combination with the low-lying octupole vibrational state.