40Ar+p Elastic scattering measurement at energies near the Coulomb barrier for optical potential study

Abstract

Nuclear optical potentials are essential for calculating nuclear cross-sections and for probing nuclear structures and dynamics. The phenomenological global optical model potentials (pGOMPs), such as Koning–Delaroche (KD) and Perey–Perey (PP) potentials, have been extensively tested and are generally accepted. However, optical potentials extrapolated at low energies where data do not exist are not always reliable. This study aims to measure new 40Ar+p elastic scattering data at low energies near the Coulomb barrier to extract optical model potential parameters. The elastic scattering of 40Ar+p in inverse kinematics was performed at energies of 4.4, 5.9, and 8.3 MeV/u using KoBRA at the RAON facility. The ELARK barrel-type silicon detector array was employed to detect scattered protons. The angular distributions of the elastic scattering cross-sections were analyzed and compared with those calculated using the GOMPs. Our measured angular distributions could not be reproduced by pGOMPs at low energies. The experimental angular distributions were analyzed to extract optical potential parameters via χ2 minimization, which were subsequently shown to satisfy the dispersion relation. The results show the limitations of the pGOMPs at lower energies near the Coulomb barrier and indicate the need for further studies of optical potentials with more experimental data to improve the reliability of pGOMPs in reproducing experimental observations. © 2026 The Authors