A charge plunger device to measure the lifetimes of excited nuclear states where transitions are dominated by internal conversion

摘要

A charge plunger device has been commissioned based on the DPUNS plunger (Taylor et al., 2013) using the in-flight mass separator MARA at the University of Jyvaeskylae. The ~(152)Sm(~(32)S,4n)~(180)Pt reaction was used to populate excited states in ~(180)Pt. A lifetime measurement of the 2_1~+ state was performed by applying the charge plunger technique, which relies on the detection of the charge state-distribution of recoils rather than the detection of the emitted γ rays. This state was a good candidate to test the charge plunger technique as it has a known lifetime and depopulates through a converted transition that competes strongly with γ-ray emission. The lifetime of the 2_1~+ state was measured to be 480(10) ps, which is consistent with previously reported lifetimes that relied on the standard γ-ray techniques. The charge plunger technique is a complementary approach to lifetime measurements of excited states that depopulate through both γ-ray emission and internal conversion. In cases where it is not possible to detect Doppler-shifted γ rays, for example, in heavy nuclei where internal conversion dominates, it may well be the only feasible lifetime analysis approach.