Jacob Heery

Lifetime measurements in Pt-178 with excited states de-exciting through gamma-ray transitions and internal electron conversions have been performed. Ionic charges were selected by the in-flight mass separatorMARAand measured at the focal plane in coincidence with the 4(1)(+) -> 2(1)(+) 257 keV gamma-ray transition detected using the JUROGAM 3 spectrometer. The resulting charge-state distributions were analysed using the differential decay curve method (DDCM) framework to obtain a lifetime value of 430(20) ps for the 2(1)(+) state. This work builds on a method that combines the charge plunger technique with the DDCM analysis. As an alternative analysis, ions were selected in coincidence with the Pt-178 alpha decay (E-alpha = 5.458(5) MeV) at the focal plane. Lifetime informationwas obtained by fitting a two-state Bateman equation to the decay curve with the lifetime of individual states defined by a single quadrupolemoment. This yielded a lifetime value of 430(50) ps for the 2(1)(+) state, and 54(6) ps for the 4(1)(+) state. An analysis method based around the Bateman equation will become especially important when using the charge plunger method for the cases where utilising coincidences between prompt gamma rays and recoils is not feasible.

The neutron -rich strontium, zirconium, and molybdenum nuclei have been observed to undergo a dramatic evolution, becoming strongly deformed around N = 60, sometimes interpreted as a quantum phase transition between "normal" and intruder configurations. Key to understanding this evolution is to understand the configurations in isolation, in regions where interference can be neglected. A deformed coexisting configuration is inferred from the presence of a 0 2 state which decreases in excitation energy with increasing neutron number, becoming the first -excited state at 98Mo. We present here the results of a low -energy Coulomb -excitation measurement of the nucleus 96Mo, extracting B(E2) values and quadrupole moments. It is found that, while the B(E2) values agree with those found in the literature, there is a significant disagreement with literature spectroscopic quadrupole moments. The results are compared with shell -model calculations using a 88Sr core with good agreement found, likely indicating that intruder structures do not significantly impact the ground -state structure, in contrast with the heavier molybdenum isotopes.