CALCULATIONS OF MICRODOSIMETRIC SPECTRA FOR BETA-PARTICLES AT A WATER-AIR INTERFACE

Calculations of microdosimetric spectra are important in attempts to i nfer mechanisms of biological action from radiobiological experiments, and also have applications in the area of radiation protection. In th is work, distributions of ionisation frequency and lineal energy in sm all volumes from beta emitters at a water-air interface are calculated . This system is a model for skin dosimetry. The Oak Ridge Electron-Tr ansport Code (OREC) is used, which computes the full Monte Carlo trans port and energy loss of a primary electron and all its secondaries in liquid water. The results are understood qualitatively on the basis of the statistics of primary ionisations and the invariance of propertie s of delta ray tracks with the energy of the primary projectile.