Beta strength to excited states in the decays of f72 mirror nuclides

Abstract The distribution and strength of the Gamow-Teller transitions have been studied in the β + decays of f 7 2 mirror nuclides. Experimental studies were performed using light-ion-induced reactions, the He-jet transport technique and the on-line isotope separator IGISOL. New transitions leading to excited states of the daughter nucleus were observed for 49 Mn, 51 Fe and 53 Co. Theoretical calculations were performed with a shell-model code employing the (f 7 2 ) n + ( f 7 2 ) n−1 0( p 3 2 , f 5 2 , p 1 2 ) 1 ) shell space. A quenching factor of th but the decays of 49 Mn and 53 Co are observed to be quenched only by a factor of 0.8. The formation of the giant Gamow-Teller resonance is clearly shown in the shell-model calculation. In the case of 53 Co about 95% of the beta strength is predicted to lie in the resonance region outside the β-decay energy window.