Search for Double Alpha Decay*

In the past few years there has been an increased effort theoretically to investigate the simultaneous emission of two alpha particles from heavy nuclei, motivating experimental searches to discover this novel mode of radioactive decay. Measured double alpha decay branching ratios would provide valuable information on the dynamics of alpha- and cluster-decay of heavy nuclei. Depending on the model used to predict double alpha decay half-lives, the results can vary widely. For the case of Rn-220, the half-life predictions range over 17 orders of magnitude. The GADGET II TPC is being used to search for Rn-220 double alpha decay by reconstructing the 3D alpha tracks event-by-event, enabling verification of each double alpha candidate in the energy spectrum. To increase the detection efficiency for double alpha events, the TPC has been modified to enable operation at higher pressures. Coupling this enhanced system with the HPGe detectors of the PXCT setup, a search for new single alpha decays to excited states of four nuclei in the Rn-220 decay chain is also being conducted in the same experiment. Recently acquired data from this experiment will be presented and discussed.