SOME LIFETIMES IN A = 15-25 MASS RANGE

The mean lifetimes of twenty excited states in 15,16N, 16,17,18,19O, 19,20F, 19,20,21,22Ne, 23,25Na and 25Mg were measured by means of the plunger technique. The levels were fed by several-nucleon transfer reactions employing beams of 14N and 16,17,18O incident on targets of 6,7,8Li, 9Be and 10B. An integral transform technique was used to fit measured fractional stopped/total ratios using the detailed flight-peak line shape as measured by a Ge(Li) detector at 0°. The measured lifetimes compared to their single-particle estimates showed M1 retardation by one to two orders of magnitude and considerable E2 enhancement. The ground state transitions from the mirror pair 19Ne(275 keV) and 19F(109.8 keV) both show equal E1 retardation. © 1969.