Lifetime measurements in heavy elements using the charge plunger technique

This research aims to measure lifetimes of heavy nuclei using the recently commissioned charge plunger device at the University of Jyväskylä Accelerator Laboratory. Lifetime measurements in heavy elements with large internal conversion coefficients prove difficult using standard plunger techniques, due to the reliance on the detection of Doppler shifted gamma-rays produced in nuclear decays at different velocity regions (before and after a degrader foil). A complementary approach for nuclei with high internal conversion coefficients is the charge plunger technique; a modification of the standard recoil distance Doppler-shift (RDDS) method, the technique utilises a charge reset foil, whereby the charge of ions is reset to a value dependent on their velocity. Once produced in fusion-evaporation reactions at a target, recoiling nuclei that decay via internal conversion may subsequently have their ionic charge increased due to the Auger effect. Varying the target-to-foil distance allows for the sensitivity of nuclear lifetimes to be probed, by counting the number of conversion events that occurred before and after the reset foil. The resulting charge shape distribution of recoil ions reflect the processes that occurred during their time of flight and allows for nuclear lifetimes to be extracted using the differential decay curve method (DDCM), or by fitting Bateman equations to the data. This research aims to make the first measurements of the lifetime of a non-isomeric state in No-254 (and possibly other transfermium nuclei) by employing the charge plunger technique described above.