Characterization of fine-pitch cadmium telluride detectors for the FOXSI sounding rocket experiment (Conference Presentation)

Abstract

We present on the detector characterization activities and flight results for fine-pitch (60um) cadmium telluride (CdTe) strip detectors designed for the Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket experiment. FOXSI, optimized for observations in the range 4-20 keV, is the first solar-dedicated instrument to utilize the technology of focusing optics for observing the Sun in hard X-rays. Each of the seven FOXSI optics modules is paired with a semiconductor strip detector from which the energy and position of each incoming photon can be derived. While the first FOXSI experiment (FOXSI-1) flew only silicon (Si) detectors, both of the next two FOXSI sounding rocket experiments (FOXSI-2 and FOXSI-3) upgraded some of the detectors to CdTe (60um pitch) for enhanced efficiency at energies >10 keV. Here we present the measurements and analysis performed to characterize components of the CdTe detector response for FOXSI-2 and FOXSI-3, including the gain, energy resolution, and efficiency. Additionally, we explore the effects of charge sharing for these fine-pitch detectors and describe how these effects are accounted for in our calibration and data analysis. Results from spectral analysis of a solar microflare using CdTe data from the FOXSI-2 flight will be shown.