Work

Systematics of the low-energy electric dipole strength in the Sn isotopic chain

Year: 2024

Type: article

Abstract: We present a systematic study of the mass dependence of the low-energy electric dipole strength (LEDS) in Sn isotopes in the range $ A = 111 - 124$ based on data obtained with the Oslo method and with relativistic Coulomb excitation in forward-angle ($p,p^\prime$) scattering. The combined data cover an energy range of $2 - 20$ MeV which permits, with minimal assumptions, a decomposition of the total strength into the contribution from the low-energy tail of the isovector giant dipole resonance (IVGDR) and possible resonance-like structures on top of it. In all cases, a resonance peaked at about 8.3 MeV is observed, exhausting an approximately constant fraction of the Thomas-Reiche-Kuhn (TRK) sum rule with a local maximum at $^{120}$Sn which might be related to shell structure effects. For heavier isotopes ($A \geq 118$) a consistent description of the data requires the inclusion of a second resonance centered at 6.5 MeV, representing the isovector response of the pygmy dipole resonance (PDR). Its strength corresponds to a small fraction of the total LEDS only and shows an approximately linear dependence on mass number. The experimental results are also compared to ab initio-based microscopic calculations to investigate the importance of an inclusion of quasiparticle vibration coupling (qPVC) for a realistic description of the LEDS. A possible interpretation of the experimentally observed two-bump structure is given.

Source: Physics Letters B

DOI: 10.1016/j.physletb.2024.139216

Authors: M. Markova, P. von Neumann-Cosel, E. Litvinova

Institution: Grand Accélérateur National d'Ions Lourds

Language: English

Topic: Nuclear physics research studies

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: diamond