Calibration of Solid State Nuclear Track Detectors for Rare Event Searches

The calibration of the CR39 and Makrofol Nuclear Track Detectors of the MoEDAL experiment at the CERN-LHC was performed by exposing stacks of detector foils to heavy ion beams with energies ranging from 340 MeV/nucleon to 150 GeV/nucleon. After chemical etching, the base areas and lengths of etch-pit cones were measured using automatic and manual optical microscopes. The response of the detectors, as measured by the ratio of the track-etching rate over the bulk-etching rate, was determined over a range extending from their threshold at Z/$\beta \sim 7$ and $\sim 50$ for CR39 and Makrofol, respectively, up to Z/$\beta \sim 92$