implantation scintillator for fast-timing measurements in beta-decay studies of rare isotopes near the N=20 island of inversion *

Understanding changes in nuclear structure as a function of proton and neutron number is critical to develop a predicative model of the atomic nucleus. Nuclear transition rates can be used as sensitive probes of underlying nuclear configurations. One method to measure longer-lived half-lives is through the direct measurement of the time delay between two emitted radiations following β decay. A β-decay experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) where radioactive nuclei were implanted within a thin CeBr₃ scintillator and a variety of states in daughter nuclei were subsequently populated. The CeBr₃ scintillator, coupled to a position-sensitive photomultiplier tube (PSPMT) was chosen due to its superior energy resolution compared to thick plastic scintillators which were used in previous experiments. Sixteen high-purity Ge detectors were situated around the CeBr₃ for γ-ray detection as well as 15 LaBr₃(Ce) detectors ideal for fast-timing measurements. Preliminary results obtained using β-γ, β-γ-γ and γ-γ timing methods will be presented.