Core Deformation Impact of One- and Two-Proton Halo $${}^{{27}}$$ S Nucleus

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NUCLEI Theory

Core Deformation Impact of One- and Two-Proton Halo

27

S Nucleus

J. Islam1), 2), 3) , F. H. M. Salih1), 2) , S. Radiman1), 2) , and K. S. Khoo1), 2)* Received January 30, 2020; revised March 31, 2020; accepted March 31, 2020

Abstract—The core deformation of a one- and two-proton halo 27 S nucleus was investigated based on experimental data. The Hamiltonian of the three-body systems and the root-mean-square (RMS) matter radii were used to calculate the theoretical value. The calculated theoretical value was analyzed using the relationship of the core deformation parameter (β2 ) with the binding energy of one- and two-proton halos and the RMS matter radii of nucleus 27 S. The Jacobi method was the primary tool used to describe the motion of the valence proton included in the wave function and was applied to the Hamiltonian of the threebody systems and the RMS matter radius. The calculation was run through MATLAB computational software. The results were shown with the experimental data. The RMS matter radius was large, and the core experienced clear deformation based on the binding energy of one- or two-valence protons ranging from –1.377 to –1.387 MeV. Nucleus 27 S exhibits one- and two-proton halos owing to the low binding energy of the valence nucleon and exhibits either an oblate or prolate shape based on the theoretical binding energy of one- or two-valence protons, respectively. DOI: 10.1134/S1063778820050129

1. INTRODUCTION Typically, stable nuclei are located at the N = Z drip line, while unstable nuclei are located at the proton- or neutron-drip lines [1]. During a 1985 radioactive nuclear beam experiment conducted by Tanihata et al., researchers discovered new exotic nuclei, finding that the nucleus of 11 Li had a large radius [2] and small binding energy [3]. Owing to the low binding energy between the valence nucleon and the nuclear core, the valence nucleon expanded away from the core, causing an increase in the matter radii leading to the formation of a nuclear halo [4]. Nuclear halo discovery opened a new field of study in nuclear physics, leading to both experimental and theoretical testing grounds to better understand these structures [5–7]. There are two types of halo nuclei: neutron halos, located near the neutron drip line; and proton halos, located near the proton drip line. Fewer studies have been performed on proton halos than on neutron halos, likely owing to the Coulomb barrier causing proton halos to be more difficult to form [8]. 1)

Nuclear Technology Research Centre, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia. 2) Department of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia. 3) Department of Physics, Mawlana Bhashani Science and Technology University, Santosh, Tangail-1902, Bangladesh. * E-mail: [email protected]

In an investigation performed on 8 B, the weaklybound valence proton combined with the density distribution caused a tail-like halo