Measurement of the track etch rates along proton and alpha particle trajectories in CR-39 and calculation of the detection efficiency

Computation of the neutron response of CR-39 detectors needs to simulate th e track formation by neutron induced charged particles taking into account the bulk etch rate and the track etch rate varying along the particle traje ctories. The latter one was determined experimentally by track length measu rement. The results allowed to derive the relationship between the track et ch rate and the restricted energy loss of the charged particles. On this ba sis, the geometrical track parameters and track etch rates as well as the c ritical angle of particle incidence could be determined for protons and alp ha particles in the energy range from 0.2 to 8.8 MeV. The energy dependence of the critical angle enabled to determine the detection efficiency for a charged particle of given energy and direction.