Improvements for heavy-ion accelerator mass spectrometry at the university of Notre Dame’s nuclear science laboratory

The detection of heavy (A > 127), long-lived trace radionuclides using accelerator mass spectrometry requires accelerator systems with high mass resolution and detectors with high efficiency, timing and energy resolution, and resistance to degradation. At the University of Notre Dame’s Nuclear Science Laboratory, a two-anode gas ionization detector, similar to others employed at ETH Zurich, Vienna, and the Australia National University, has been built to be used with a time-of-flight system. This new detector is more robust than the existing Si detector, with two high resolution ΔE segments. This work describes the detector design and modifications to the time-of-flight system, summarizes the observed performance, and provides comparisons to a Geant4 model. The energy resolution (9% for 44 MeV 238U beams) was found to be better than the existing Si detector and its larger acceptance contributed a factor of five improvement (from 4% to 20%) in transmission through the detection system for uranium beams.