Higher-spin structures in 21F and 25Na
Abstract
Excited states were investigated in 21F and 25Na using the 9Be(14C,p n γ ) reaction at 30, 35, and 45 MeV and the 9Be(18O,p n γ ) reaction at 35 MeV. Protons were detected and identified in an E -Δ E telescope at 0∘ in coincidence with one or more γ radiations in the FSU Compton-suppressed Ge detector array. Many new levels and electromagnetic decays were observed, especially among the higher spin states. Angular distributions and mean lifetimes were measured wherever possible in both nuclei. The energy levels of the positive-parity states in the two nuclei agree rather well with shell model calculations using both the USDA and WBP interactions up to the highest spins observed of 13 /2 ℏ . Both a weak coupling approximation and shell model calculations using the WBP interaction generally reproduce the negative-parity states in 21F. The shell model calculations reproduce relatively well the measured M 1 and E 2 transitions in both nuclei, but overpredict the parity-changing E 1 transitions in 21F, the only nucleus in which negative-parity states were observed in the present experiment.
- Publication:
-
Physical Review C
- Pub Date:
- September 2015
- DOI:
- 10.1103/PhysRevC.92.034301
- Bibcode:
- 2015PhRvC..92c4301V
- Keywords:
-
- 27.30.+t;
- 23.20.En;
- 21.60.Cs;
- 25.60.Je;
- 20<
- =A<
- =38;
- Angular distribution and correlation measurements;
- Shell model;
- Transfer reactions