Resolving power of pixel detector Timepix for wide-range electron, proton and ion detection

The resolving power of the Timepix detector for wide-range charged particle detection has been examined and evaluated in defined radiation fields. The goal is to broadly characterize mixed-radiation fields consisting namely of X-rays and charged particles in terms of particle-types (species), spectral response (energy loss) and direction in wide field-of-view (essentially 2 pi) with a single compact tracking detector. Tests and calibration measurements were performed with the same device at electron, proton and ion fields at various energies and incident directions. Event-by-event detection, together with pattern recognition analysis of the single particle tracks, are exploited to analyze events according to three degrees of freedom-the particle type (X-rays, light and heavy charged particles), energy range (low or high energy-depending on their range being smaller or larger than the pixel size of the detector semiconductor sensor) and direction (incident angle to the sensor plane). Characteristic values are determined for the cluster analysis morphology parameters, the particles stopping power or Linear Energy Transfer and derived correlated quantities. Ratios and correlations between selected parameters are analyzed including 2D-scatter plots. A physics-based wide-range classification is proposed for a total of 8 broad event groups-in terms of light charged particles (electrons, muons) of both low and high energy incident perpendicular (type 1, including X-rays) or high energy non-perpendicular (type 5), protons of low energy omnidirectional (type 2) and high energy non-perpendicular (type 6), alpha particles and light ions of low energy omnidirectional (type 3) and high energy non-perpendicular (type 7), and heavy ions of low energy omnidirectional (type 4) and high energy non-perpendicular (type 8).