Spectral calibration and modeling of the NuSTAR CdZnTe pixel detectors

Takao Kitaguchi; Brian W. Grefenstette; Fiona A. Harrison; Hiromasa Miyasaka; Varun B. Bhalerao; Walter R. Cook III; Peter H. Mao; Vikram R. Rana; Steven E. Boggs; Andreas C. Zoglauer

doi:10.1117/12.896972

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13 September 2011 Spectral calibration and modeling of the NuSTAR CdZnTe pixel detectors

Takao Kitaguchi, Brian W. Grefenstette, Fiona A. Harrison, Hiromasa Miyasaka, Varun B. Bhalerao, Walter R. Cook III, Peter H. Mao, Vikram R. Rana, Steven E. Boggs, Andreas C. Zoglauer

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Proceedings Volume 8145, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XVII; 814507 (2011) https://doi.org/10.1117/12.896972
Event: SPIE Optical Engineering + Applications, 2011, San Diego, California, United States

Abstract

The Nuclear Spectroscopic Telescope Array (NuSTAR) will be the first space mission to focus in the hard X-ray (5-80 keV) band. The NuSTAR instrument carries two co-aligned grazing incidence hard X-ray telescopes. Each NuSTAR focal plane consists of four 2 mm CdZnTe hybrid pixel detectors, each with an active collecting area of 2 cm x 2 cm. Each hybrid consists of a 32x32 array of 605 μm pixels, read out with the Caltech custom low-noise NuCIT ASIC. In order to characterize the spectral response of each pixel to the degree required to meet the science calibration requirements, we have developed a model based on Geant4 together with the Shockley-Ramo theorem customized to the NuSTAR hybrid design. This model combines a Monte Carlo of the X-ray interactions with subsequent charge transport within the detector. The combination of this model and calibration data taken using radioactive sources of ⁵⁷Co, ¹⁵⁵Eu and ²⁴¹Am enables us to determine electron and hole mobility-lifetime products for each pixel, and to compare actual to ideal performance expected for defect-free material.

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Takao Kitaguchi, Brian W. Grefenstette, Fiona A. Harrison, Hiromasa Miyasaka, Varun B. Bhalerao, Walter R. Cook III, Peter H. Mao, Vikram R. Rana, Steven E. Boggs, and Andreas C. Zoglauer "Spectral calibration and modeling of the NuSTAR CdZnTe pixel detectors", Proc. SPIE 8145, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XVII, 814507 (13 September 2011); https://doi.org/10.1117/12.896972

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