TY - JOUR
T1 - Development of a spectral model based on charge transport for the Swift/BAT 32K CdZnTe detector array
AU - Sato, Goro
AU - Parsons, Ann
AU - Hullinger, Derek
AU - Suzuki, Masaya
AU - Takahashi, Tadayuki
AU - Tashiro, Makoto
AU - Nakazawa, Kazuhiro
AU - Okada, Yuu
AU - Takahashi, Hiromitsu
AU - Watanabe, Shin
AU - Barthelmy, Scott
AU - Cummings, Jay
AU - Gehrels, Neil
AU - Krimm, Hans
AU - Markwardt, Craig
AU - Tueller, Jack
AU - Fenimore, Ed
AU - Palmer, David
PY - 2005/4/1
Y1 - 2005/4/1
N2 - The properties of 32K CdZnTe (4×4mm2 large, 2 mm thick) detectors have been studied in the pre-flight calibration of the Burst Alert Telescope (BAT) on-board the Swift Gamma-ray Burst Explorer (scheduled for launch in November 2004). In order to understand the energy response of the BAT CdZnTe array, we first quantify the mobility-lifetime (μτ) products of carriers in individual CdZnTe detectors, which produce a position dependency in the charge induction efficiency and results in a low-energy tail in the energy spectrum. Based on a new method utilizing 57Co spectra obtained at different bias voltages, the μτ for electrons ranges from 5.0×10-4 to 1.0×10-2cm2V-1 while the μτ for holes ranges from 1.3×10-5 to 1.8×10-4cm2V-1. We find that this wide distribution of μτ products explains the large diversity in spectral shapes between CdZnTe detectors well. We also find that the variation of μτ products can be attributed to the difference of crystal ingots or manufacturing harness. We utilize the 32K sets of extracted μτ products to develop a spectral model of the detector. In combination with Monte Carlo simulations, we can construct a spectral model for any photon energy or any incident angle.
AB - The properties of 32K CdZnTe (4×4mm2 large, 2 mm thick) detectors have been studied in the pre-flight calibration of the Burst Alert Telescope (BAT) on-board the Swift Gamma-ray Burst Explorer (scheduled for launch in November 2004). In order to understand the energy response of the BAT CdZnTe array, we first quantify the mobility-lifetime (μτ) products of carriers in individual CdZnTe detectors, which produce a position dependency in the charge induction efficiency and results in a low-energy tail in the energy spectrum. Based on a new method utilizing 57Co spectra obtained at different bias voltages, the μτ for electrons ranges from 5.0×10-4 to 1.0×10-2cm2V-1 while the μτ for holes ranges from 1.3×10-5 to 1.8×10-4cm2V-1. We find that this wide distribution of μτ products explains the large diversity in spectral shapes between CdZnTe detectors well. We also find that the variation of μτ products can be attributed to the difference of crystal ingots or manufacturing harness. We utilize the 32K sets of extracted μτ products to develop a spectral model of the detector. In combination with Monte Carlo simulations, we can construct a spectral model for any photon energy or any incident angle.
KW - BAT
KW - CdZnTe
KW - Gamma-ray astronomy
KW - Mobility-lifetime products
KW - Spectral model
KW - Swift
UR - http://www.scopus.com/inward/record.url?scp=20144378089&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=20144378089&partnerID=8YFLogxK
U2 - 10.1016/j.nima.2005.01.078
DO - 10.1016/j.nima.2005.01.078
M3 - Article
AN - SCOPUS:20144378089
SN - 0168-9002
VL - 541
SP - 372
EP - 384
JO - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
IS - 1-2
ER -