Probing the j dependence of angular distributions and N = 20 shell rigidity via the S 36 ( p , d ) S 35 reaction

An investigation of the N = 20 36 S nucleus has been performed through a detailed study of the 36 S(p, d) 35 S neutron-removal reaction, employing a 66 MeV proton beam at iThemba LABS and an innovative target design.Using the high-resolution K=600 magnetic spectrometer, 98 states in 35 S were identified up to 16 MeV excitation energy, including 47 previously unobserved states.Angular distributions and spectroscopic factors, including isobaric analog state contributions, were extracted for 81 levels.A pronounced j-dependence in the angular distributions of ℓ = 2 states provides refined insights into the spin-orbit splitting.Finite-range adiabatic distorted wave approximation calculations qualitatively reproduce the observed j-dependence.Comparisons of the measured 1d 5/2 spectroscopic strength distribution with large-scale shell-model and ab-initio calculations show good agreement overall, and the robustness of the N = 20 shell closure in 36 S is confirmed when comparing the relatively low f p orbital occupancies in 40 Ca and 36 S across the Fermi surface.This study underscores the utility of neutron-removal reactions in probing nuclear structure and the Fermi surface of sd nuclei and beyond.The findings advance our understanding of shell evolution and offer constraining data for theoretical models.