4 research outputs found
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????) 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)
Wide-range tracking and LET-spectra of energetic light and heavy charged particles
We developed a highly-selective technique to measure the energy loss and linear-energy-transfer (LET) spectra of energetic charged particles in high-resolution and over a large collection of particle-event types. Precise and wide-range spectral and tracking measurements were performed with a single semiconductor pixel detector. The quantum-counting sensitivity, high-granularity and per-pixel spectrometric response of the Timepix ASIC chip enable the detailed spectral-tracking registration of single charged particles across the detector semiconductor sensor. Both the deposited energy along the particle trajectory (energy loss) and the path length of the particle track across the semiconductor sensor are precisely measured for each particle. This allows for the determination of the particle LET in silicon in high accuracy and over a wide-range of energies, particle types and directions. The tracking and energy loss response together with the resolving power at the particle-event level make it possible to selectively provide LET distributions of the light and heavy charged particle components in mixed-radiation and omnidirectional fields. This technique applies to energetic (E > 10 MeV/u) charged particles generating tracks greater than the pixel size and incident at nonperpendicular direction (>20◦) to the sensor plane. The technique applies also to electrons of energy above few MeV as well as highly energetic and minimum-ionizing-particles (MIPs). We make use of existing and in part newly collected data at well-defined radiation fields with proton and light ion beam accelerators. Flexible measurements, ease of deployment and online response are possible by the use of compact readout electronics such as the miniaturized radiation camera MiniPix (size < 8 cm, weight < 50 g) operable by any PC. Results are given for protons and light ions (He, C) of selected energies above 10 MeV/u and directions (2π FoV). We include also electrons (20 MeV). Selective and detailed LET spectra are produced over a wide range (10−1 to 102 keV/μm) in silicon