MONTE-CARLO SIMULATION OF RANGE AND ENERGY DEPOSITION BY ELECTRONS INGASEOUS AND LIQUID WATER

A stochastic simulation method employing suitable experimentally based cross sections has been developed for probing the spatial distributio n of energy loss and the trajectory of 100 eV to 1 MeV electrons in ga seous and liquid water. Elastic collisions and large-energy-loss inela stic collisions strongly influence the passage of electrons such that the separation between the initial and final (E = 25 eV) position is c onsiderably smaller than the path length. At all energies, the mean ax ial and the mean radial penetrations are somewhat similar, however, th e former is strongly influenced by inelastic collisions and the latter by elastic collisions. The effect of phase on the density-normalized range is small for energetic electrons, but differences are apparant a t the lowest energies, <2 keV. The spatial distribution of energy depo sition shows a marked dependence on electron energy. The spatial depen dence of radial energy deposition and dose distributions in the axial and radial directions have been calculated.