Background: The density of most nuclei is constant in the central region and is smoothly decreasing at the surface. A depletion in the central part of the nuclear density can have nuclear structure effects leading to the formation of “bubble” nuclei. However, probing the density profile of the nuclear interior is, in general, very challenging.

Purpose: The aim of this paper is to investigate the nuclear bubble structure, with nucleon-nucleus scattering, and quantify the effect that the bubble structure has on the nuclear surface profile.

Method: We employed high-energy nucleon-nucleus scattering, using the Glauber model to analyze various reaction observables, which helps in quantifying the nuclear bubble. The effectiveness of this method is tested on ${}^{28}\mathrm{Si}$ with harmonic-oscillator (HO) densities, before applying it on even-even $N=14$ isotones, in the $22\le A\le 34$ mass range, with realistic densities obtained from antisymmetrized molecular dynamics (AMD).

Results: Elastic scattering differential cross sections and reaction probability for the proton-${}^{28}\mathrm{Si}$ reaction are calculated using the HO density to design tests for signatures of the nuclear bubble structure. We then quantify the degree of bubble structure for $N=14$ isotones with the AMD densities by analyzing their elastic scattering at 325, 550, and 800 MeV incident energies. The present analyses suggest ${}^{22}\mathrm{O}$ as the most measurable candidate for a bubble nucleus, among even-even $N=14$ isotones, in the $22\le A\le 34$ mass range.

Conclusion: We have shown that the bubble structure information is imprinted on the nucleon-nucleus elastic scattering differential cross section, especially in the first diffraction peak. Bubble nuclei tend to have a sharper nuclear surface and deformation seems to be a hindrance in their emergence.

• Received 11 June 2020
• Revised 2 August 2020
• Accepted 15 September 2020

DOI:https://doi.org/10.1103/PhysRevC.102.034619