Timepix3 Chip: Calibration Procedure and Results

Abstract:

The Timepix3 (TPX3) device is a low power radiation, single-photon counting detector of the Medipix family, developed at CERN by international collaboration. The readout chip is bump-bonded to either Si or CdTe as a radiation-sensitive material. By utilizing two pixel-modes of operation, Time over Threshold (ToT) and Time-of-Arrival (ToA), it can measure both time and energy synchronously. Pixet, the TPX3 chip's software readout package, boasts many user-friendly functions to prepare the chip, take data, and display spectra. Tools such as the Threshold DAC scan allow users to measure spectra directly.

We report in detail the development and testing of the HXR Imager detector assembly based on Timepix 3 detectors. We describe the characteristics and differences for CdTe and Si substrate detectors as well as an efficient full calibration procedure for both global and per-pixel calibration of the TPX3 chip. We discuss the current state of a 2x2 CdTe TPX3 array board design in preparation to be used on the FOXSI-4 (Focusing Optics X-ray Solar Imager) sounding rocket experiment and other space missions. Our method for energy and time walk calibration includes using radioactive sources, fluorescence targets, as well as sampling the detector energy response function using test pulses. Due to the TPX3 chips accessibility, capability, and resolution, it is an ideal candidate for applications in space and solar astrophysics in the 3-100 keV range