Alpha-particle calibration of CR-39 using a beehive collimator

A device to determine the detection efficiency of CR-39 for alpha particles is presented. A beehive collimator restricted the angle of incidence of alpha particles on a CR-39 sheet, such that the total number of alpha emitters could be determined. This makes it possible to obtain the critical angle of incidence, ΘC, and the maximum angle of incidence resulting in round (diameter ratio <1.100) etch pits, Θmax. In this work, these angles were determined for incidence energies around 7.5 MeV (more specifically 6.1 and 8.8 MeV).