Critical rate of energy loss for registration of charged particles in cellulose nitrate

Cellulose nitrate films LR-115 type II (Kodak-Pathe) have been exposed, at right angles, to alpha-particle beams in the energy range 2.5-5.5 MeV. From measurements of both through-etched track diameter and through-etched track density, a critical rate of energy loss for track registration of (0.85 +- 0.05) MeV cm2/mg has been derived, which corresponds to a critical alphaparticle energy of (4.6 +- 0.4) MeV. These results are compatible with those obtained by other authors whenever similar etching conditions have been used. The concepts of a threshold rate of energy loss and a threshold energy for etched-track formation are introduced, and their values are obtained from the experiment as being (0.80 +- 0.05) MeV cm2/mg and (5.1 +- 0.4) MeV, respectively. In addition, the present work provides a suitable set of useful reference data for further applications of such plastic nuclear track detector in problems concerned with the detection of low-energy alpha particles. (orig.)