Optimization of a timing scintillator for the MoNA-Sweeper setup at FRIB*

The MoNA Collaboration performs experiments to measure neutron-unbound states using invariant mass spectroscopy. This method requires the coincident measurement of one or more decay neutrons, the resulting charged fragment, and sometimes gamma-rays. A central aspect of this analysis is to identify the charged fragments resulting from the decay of the populated unbound states. With the Facility for Rare Isotope Beams (FRIB) currently in operation, higher energy and intensity beams allow for the study of neutron-unbound states in higher mass systems (A > 30). Sufficient isotopic separation of charged fragments in this mass region using the typical MoNA-Sweeper setup requires a Time-of-Flight (ToF) resolution of better than 100 ps. A high-resolution SiPM-based plastic scintillation detector design is being investigated as an alternative to the well-established PMT-based plastic scintillation detector for ToF measurements. A prototype is under development following Geant4 simulations that were performed to optimize the timing resolution of the SiPM-based detector design, and to compare it to the timing resolution obtained using a PMT-based design. Preliminary results from this study will be presented and discussed.