Neutron single-particle strength in silicon isotopes: Constraining the driving forces of shell evolution

Abstract

Shell evolution is studied in the neutron-rich silicon isotopes 36,38,40 Si using neutron single-particle strengths deduced from one-neutron knockout reactions. Configurations involving neutron excita- tions across the N = 20 and N = 28 shell gaps are quantified experimentally in these rare isotopes. Comparisons with shell model calculations show that the tensor force, understood to drive the col- lective behavior in 42 Si with N = 28, is already important in determining the structure of 40 Si with N = 26. New data relating to cross-shell excitations provide the first quantitative support for repulsive contributions to the cross-shell T = 1 interaction arising from three-nucleon forces.

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Cited by in corpus (4)

• Quenching of single-particle strength from direct reactions with stable and rare-isotope beams
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• Single-neutron knockout from ${}^{20}\text{C}$ and the structure of ${}^{19}\text{C}$
• The calculation of single-nucleon energies of nuclei by considering two-body effective interaction, n(k,rho), and a Hartree-Fock inspired scheme