Feasibility of Q-value Determinations Using a Thick Ge Detector

The rapid-neutron capture process is responsible for the creation of about half of the neutron-rich heavy elements above Fe. The path of the r-process depends sensitively on the nuclear masses of the isotopes involved. To better constrain the r-process path, experimental masses can be determined and compared with theoretical calculations. The relative mass between two members of an isobaric chain can be calculated from the beta-decay Q value inferred from a measurement of the beta-decay electron energy distribution. The National Superconducting Cyclotron Laboratory has a successful beta-decay spectroscopy program exploring the characteristics of the decay of neutron-rich nuclei which was recently upgraded with a 1-cm thick central implantation Ge detector. To determine the feasibility of using a thick planar Ge detector to determine relative masses based on Q-value determinations, a measurement of the beta-decay electron distribution was performed. A cocktail of radioactive ions were implanted into the detector around 67Fe and their subsequent beta-decays were monitored. To further examine the beta-decays of these radioactive ions and the feasibility of using a planar Ge detector to obtain relative masses from Q-value measurements, the system will be compared with Geant4 simulations and previously measured mass differences.