Investigating ionisation cluster size distribution due to sub-1 keV electrons in view of Heisenberg's Uncertainty

Abstract

As the wavelengths of low energy electrons become comparable with the length scale of the mean ionisation step size, each event particle should be treated with care as the condition outlined in Heisenberg's uncertainty principle (HUP) should also be satisfied. Within this quantum-classical regime, spatial delocalisations of individual ionisation event sites that are generated outside the target region are calculated, and particular attention is given to the validity of using classical transport methods in simulations of nanodosimetric parameters such as mean cluster size, first and second moments, variance and cumulative frequency of ionisation cluster-size probability distributions. This paper presents the comparison between conventionally calculated nanodosimetric quantities and the ones where interacting particles are treated semi-classically with spatial uncertainties satisfied by HUP. The simulated primary charged particles are electrons of energies between 100 eV and 1 keV in DNA equivalent target aqueous water volumes using GEANT4-DNA.