Microdosimetric Aspects of 0.3- to 20-MeV Proton Tracks: I. Crossers

Track structures of fast protons obtained by computer simulation using a detailed-history Monte Carlo method were evaluated to obtain stochastic frequency distributions for energy imparted and number of ionizations. These microdosimetric quantities were calculated for 0.3to 20-MeV protons passing through spherical sites (crossers) of 2 nm to 1 Am diameter in unit density water. From the distributions, the dependencies of their first two moments on ion energy, site size, and position of the track within the site were computed. The frequency distribu