On thermalization of positrons in water vapour

POSTER

Abstract

Water being the main component of the human tissue is the primary candidate for the basis of models describing positron diagnostics and therapy. Our calculations are based on the elementary binary cross sections measured or calculated. We use a Monte Carlo code following all individual collisions and trajectories allowing for the addition of external fields and accurate representation of non-conservative processes. In order to obtain realistic results completeness should be achieved for energy, momentum and number balances. Rather than determining transport coefficients which have only been measured in few cases for positrons we determine other observables. We determine the thermalization of a group of positrons released at a point in water vapour. The thermalization times may be scaled using Nt scaling. We also calculate the range of positrons, the corresponding diffusion coefficient and show shapes of individual trajectories. Finally we also establish the energy loss spectrum on the basis of binary processes. This allows us comparisons with other codes used to model transport of positrons.

Authors

  • Srdjan Marjanovic

    • Institute of Physics Belgrade, University of Belgrade, Serbia
    • Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Zemun, Serbia

  • Ana Bankovic

    • Institute of Physics Belgrade, University of Belgrade, Serbia
    • Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Zemun, Serbia

  • Stephen Buckman

    • Centre for Antimatter-Matter Studies, Australian National University, Canberra, ACT

  • Gustavo Garcia

    • Instituto de F\'isica Fundamental, Consejo Superior de Investigaciones Cient\'ificas, Madrid, Spain

  • Ronald White

    • Centre for Antimatter-Matter Studies, James Cook University, Townsville, Australia

  • Michael Brunger

    • Physics Department, Flinders University of South Australia, Adelaide, South Australia
    • ARC Centre for Antimatter-Matter Studies, School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 Australia
    • ARC Centre of Excellence for Antimatter-Matter Studies
    • Flinders University

  • Milovan Suvakov

    • Institute of Physics Belgrade, University of Belgrade, Serbia
    • Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Zemun, Serbia

  • Gordana Malovic

    • Institute of Physics Belgrade, University of Belgrade, Serbia

  • Sasa Dujko

    • Institute of Physics Belgrade, University of Belgrade, Serbia

  • Zoran Lj. Petrovic

    • Institute of Physics, University of Belgrade, PO Box 68, Zemun 11080, Belgrade, Serbia
    • Institute of Physics Belgrade, University of Belgrade, Serbia
    • Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Zemun, Serbia