An upgraded track structure model: experimental validation.

The track nanodosemeter developed at the National Laboratories of Legnaro (LNL), Italy allows the direct investigation of the properties of particle tracks, by measuring ionisation-cluster-size distributions caused by ionising particles within a 'nanometre-sized' target volume while passing it at a well-specified impact parameter. To supplement the measurements, a dedicated Monte Carlo code was developed which is able to reproduce the general shape of measured cluster-size distributions with a satisfactory quality. To reduce the still existing quantitative differences between measured and simulated data, the validity of cross sections used in the Monte Carlo model was revisited again, taking into account the large amount of data available now from recent track structure measurements at LNL. Here, special emphasis was laid on a deeper and detailed investigation of the cross sections applied to calculate the energy of secondary electrons after impact ionisation of primary particles: the cross sections due to the HKS model and the so-called Rudd model. Representative results for 240 MeV (12)C-ions are presented.