$p$-$sd$ shell gap reduction in neutron-rich systems and cross-shell excitations in ${}^{20}$O

Abstract

Excited states in ${}^{20}$O were populated in the reaction ${}^{10}$Be(${}^{14}$C,$\alpha$) at Florida State University. Charged particles were detected with a particle telescope consisting of 4 annularly segmented Si surface barrier detectors and $\gamma$ radiation was detected with the FSU $\gamma$ detector array. Five new states were observed below 6 MeV from the $\alpha$-$\gamma$ and $\alpha$-$\gamma$-$\gamma$ coincidence data. Shell model calculations suggest that most of the newly observed states are core-excited 1p-1h excitations across the $N=Z=8$ shell gap. Comparisons between experimental data and calculations for the neutron-rich O and F isotopes imply a steady reduction of the $p$-$sd$ shell gap as neutrons are added.

References in corpus (2)

• Onset of intruder ground state in exotic Na isotopes and evolution of the N=20 shell gap
• Discrete and continuum spectra in the unified shell model approach

Cited by in corpus (4)

• Gamow shell model and realistic nucleon-nucleon interactions
• Antisymmetrized molecular dynamics studies for exotic clustering phenomena in neutron-rich nuclei
• Testing ab initio nuclear structure in neutron-rich nuclei: lifetime measurements of second 2+ states in 16C and 20O
• One-neutron knockout reaction of 17C on a hydrogen target at 70 MeV/nucleon