Mean lifetimes of 20 out of 31 bound levels in [Formula Presented] below an excitation energy of 8.0 MeV are deduced from the Doppler-broadened [Formula Presented]-ray line shapes produced in the reactions [Formula Presented] and [Formula Presented] Of the 20 levels, lifetimes for 4 are reported here for the first time. For the remaining 16 levels, the lifetime values obtained in this work are considered to be more reliable and accurate than those reported in the literature. Compared to lifetime measurements reported in the literature, significant procedural improvements have been made by (i) using the entire line shape in the data analysis, (ii) making measurements with targets implanted in high-stopping-power media, and (iii) simulating with the Monte-Carlo method the slowing-down process, experimental conditions, and the delayed feeding from higher levels to the level being analyzed. The low-lying portion of the level scheme, level lifetimes, [Formula Presented]-ray branchings, [Formula Presented] mixing ratios, and reduced transition probabilities are compared with shell-model calculations. The reduced [Formula Presented] values for 16 out of 18 transitions and [Formula Presented] values for 5 out of 10 transitions are reproduced to within a factor of 5. A one-to-one correspondence between 33 experimental and predicted states is established up to 8.2 MeV for both positive- and negative-parity states.
ASJC Scopus subject areas
- Nuclear and High Energy Physics