A Test of Geant4 Simulation Efficiency Predictions for the Short-lived Isotope Counting System*

 Ultrafast high-power lasers may be used to generate short pulses of energetic ions that can be used for nuclear activation cross section measurements.  The Short-Lived Isotope Counting System (SLICS) was developed to count the beta decays of radioactive product nuclei resulting from light ion reactions generated in this way.  One important SLICS parameter, which has been determined using a Geant4 simulation, is the detection efficiency, the ratio of detected betas to number of product nuclei.  To test this prediction, an experiment was carried out using the SUNY Geneseo Pelletron.  A deuteron beam incident on a thin natural Li target created 840 ms half-life ⁸Li via the ⁷Li(d,p)⁸Li reaction. The beta particles from the ⁸Li decay were identified and counted by the SLICS detector, a dE-E phoswich detector telescope.  Alpha particles from ⁶Li(d,α)⁴He on the same natural lithium target were counted by a silicon surface barrier detector at various backward angles.  The efficiency of the SLICS detector was determined using the number of the α and β particles counted by the two detectors and the previously measured cross- sections and Li isotopic abundances.