Work

Implications of a weakening N=126 shell closure away from stability for r-process astrophysical conditions

Year: 2025

Type: article

Abstract: The formation of the third r -process abundance peak near A ∼ 195 is highly sensitive to both nuclear structure far from stability and the astrophysical conditions that produce the heaviest elements. In particular, the N = 126 shell closure plays a crucial role in shaping this peak. Experimental data hints that the shell weakens as proton number departs from Z = 82 , a trend largely missed by global mass models. To investigate its impact on r -process nucleosynthesis, we employ both standard global models with strong closures and modified Duflo-Zuker (DZ) models that reproduce the weakening, combined with three sets of β − -decay rates. Strong shell closures generate sharply peaked abundances, whereas weakened closures consistent with the experimental trend produce broader, flatter patterns. Accurately reproducing the solar third peak under weakened shell strength requires sufficiently neutron-rich conditions that significant fission occurs, and slower decay rates. These results demonstrate that a weakening N = 126 shell closure away from stability imposes significant constraints on the astrophysical environments of the r -process and underscores the need for precise mass measurements and improved characterization of β − -decay properties in this region.

Source: Physics Letters B

DOI: 10.1016/j.physletb.2025.140109

Authors: Mengke Li, Gail C. McLaughlin, Rebecca Surman

Institutions: University of Notre Dame, University of California, Berkeley, North Carolina State University

Language: English

Topic: Nuclear physics research studies

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: diamond