A Monte Carlo track structure code for electrons (similar to 10 eV-10 keV)and protons (similar to 0.3-10 MeV) in water: partitioning of energy and collision events
D. Emfietzoglou et al., A Monte Carlo track structure code for electrons (similar to 10 eV-10 keV)and protons (similar to 0.3-10 MeV) in water: partitioning of energy and collision events, PHYS MED BI, 45(11), 2000, pp. 3171-3194
An event-by-event Monte Carlo simulation code for track structure studies i
s described. In the present form the code transports protons (similar to0.3
-10 MeV) and electrons (similar to 10 eV-10 keV) in a water medium in the g
as phase approximation. For the type of particles and energy range consider
ed, ionization, electronic excitation and electron elastic scattering are t
he most important collision events accounted for in the transport simulatio
n. Efforts were made to ensure that the analytic representation of the vari
ous interaction cross sections rests on well established experimental data
and theory. For example, the secondary-electron spectrum as well as partial
and total ionization cross sections are represented by a semitheoretical f
ormulation combining Bethe's asymptotic expansion and binary-encounter theo
ry. Binding effects for five levels of ionization and eight levels of elect
ronic excitation of the water molecule are explicitly considered. The valid
ity of the model cross sections is examined against available experimental
data and theoretical predictions from other similar studies. Results pertai
ning to the partitioning of energy loss and interaction events for the firs
t-collision probability and nanometre-size track segments are presented.