Lifetime measurement of the Ex = 2485.3 keV level of 25Al populated through 24Mg(p,γ)25Al resonance reaction

Abstract

Results of our experimental study of the ²⁴Mg${(p,\gamma )}^{25}$Al resonance reaction at E${}_p{}^{lab}=223$ keV are presented. The proton beam energy is varied from 220 to 265 keV. An evaporated Mg target with thick Ta backing is used. We remeasure a mean lifetime of $\tau ={6.04}_{-2.65}^{+3.03}$ fs for the E${}_x=2485.3$ keV level of ²⁵Al, using Doppler shift attenuation (DSA) method. Three most successfully used empirical effective interactions developed for the sd shell by Wildenthal (w), Chung-Wildenthal (cw) and Preedom-Wildenthal (pw), are utilized to calculate energy spectra, spectroscopic factors, beta decay properties, transition probabilities and the lifetime of the resonance state in ²⁵Al within the framework of nuclear shell model. The theoretical results agree reasonably well with the experimental data. However, a detailed study for each set to identify the most preferred interaction for this nucleus is performed. Calculated lifetimes using two of the interactions (w, cw) agree better with the central value of the experimental lifetime of the resonance state measured in the present work.