2021

Heery, J.; Barber, L.; Vilhena, J.; Nara Singh, B. S.; Herzberg, R.-D.; Cullen, D. M.; Müller-Gatermann, C.; Beeton, G.; Bowry, M.; Dewald, A.; Grahn, T.; Greenlees, P. T.; Illana, A.; Julin, R.; Juutinen, S.; Keatings, J. M.; Leino, M.; Luoma, M.; O’Donnell, D.; Ojala, J.; Pakarinen, J.; Rahkila, P.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Sinclair, J.; Smith, J. F.; Sorri, J.; Spagnoletti, P.; Tann, H.; Uusitalo, J.; Zimba, G.

Lifetime measurements in 178Pt with excited states de-exciting through γ-ray transitions and internal electron conversions have been performed. Ionic charges were selected by the in-flight mass separator MARA and measured at the focal plane in coincidence with the 4+1→2+1 257keV γ-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 178Pt alpha decay (Ealpha=5.458(5) MeV) at the focal plane. Lifetime information was obtained by fitting a two-state Bateman equation to the decay curve with the lifetime of individual states defined by a single quadrupole moment. 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 γ rays and recoils is not feasible.