Directional detection of charged particles and cosmic rays with the miniaturized radiation camera MiniPIX Timepix

Abstract

We evaluate and characterize the directional response of the semiconductor pixel detector Timepix to charged particles and secondary cosmic rays. The detector granularity and per-pixel spectrometric response enable to perform directional sensitive tracking of energetic charged particles in wide field-of-view. In the highly integrated MiniPIX readout the detector serves as a miniaturized, low-power and easily deployable particle micro-tracker. Angular measurements require normalization for the acceptance angle and geometric factor which are described and taken into account. The methodology and evaluation of directional response are developed for light charged particles and atmospheric secondary cosmic rays. Tests and calibration of angular resolution were performed with electron and proton beams. Resulting angular distributions are expressed in terms of elevation and azimuth angles in 14 bins and 36 bins, respectively, over the full 2π acceptance range. For zenith angle β > 28° the angular distribution is fitted by ∼ cos n (β) with n = 2.0 ± 0.2 expected from secondary cosmic ray muon distribution.