Fast-timing measurements in the ground-state band of 114Pd

Abstract

Using a hybrid Gammasphere array coupled to 25 LaBr3(Ce) detectors, the lifetimes of the first three levels of the yrast band in 114Pd, populated via 252Cf decay, have been measured. The measured lifetimes are τ2+ = 103(10) ps, τ4+ = 22(13) ps, and τ6+ 10 ps for the 2+ 1 , 4+ 1 , and 6+ 1 levels, respectively. Palladium-114 was predicted to be the most deformed isotope of its isotopic chain, and spectroscopic studies have suggested it might also be a candidate nucleus for low-spin stable triaxiality. From the lifetimes measured in this work, reduced transition probabilities B(E2; J → J − 2) are calculated and compared with interacting boson model, projected shell model, and collective model calculations from the literature. The experimental ratio RB(E2) = B(E2; 4+ 1 → 2+ 1 )/B(E2; 2+ 1 → 0+ 1 ) = 0.80(42) is measured for the first time in 114Pd and compared with the known values RB(E2) in the palladium isotopic chain: the systematics suggest that, for N = 68, a transition from γ -unstable to a more rigid γ -deformed nuclear shape occurs.