A fast, compact particle detector for tuning radioactive beams at ATLAS

Radioactive ion beams (RIB) at the Argonne Tandem Linear Accelerator System (ATLAS) are produced either from the in-flight method at 5-15 MeV/u for A < 30, or via reacceleration of fission fragments from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) at 4-10 MeV/u for 80 < A < 160. These RIB are typically accompanied by contaminant beams >100x more intense. The goal of this work is to develop a fast (>10⁵ pps), compact (retractable from the beam line) particle detector capable of A and Z identification to enable accelerator optimization on the exact species of interest. The detector should have an energy resolution of ≤5% and be resistant to radiation damage. A gas ionization chamber supplemented with an inorganic scintillator was chosen as the basic conceptual design. GSO:Ce was chosen as the primary candidate scintillator due to a demonstrated energy resolution of ~3% for 15 MeV/u He and less irradiation induced performance degradation than other candidate materials.