Octupole transitions in 19F and other s–d shell nuclei

Abstract

The deformed Nilsson model is first applied to the study of the E3 transition from the 1.347 MeV state (Jπ = 5/2−) in 19F to the ground state (Jπ = 1/2+). The value 0.56 W.u. is obtained while the experimental one is 7.6 ± 1.3 W.u. A deformed schematic RPA calculation is then performed to describe a Q3,0 octupole oscillation. An enhanced value of 2 W.u. is obtained without changing excessively the Nilsson configuration of the excited band head. Octupole sum rules are derived and evaluated for 16O, 19F, and 20Ne. A study is made of the interplay between permanent quadrupole deformations and octupole vibrations.