TY - JOUR
T1 - Simulating CCDs for the Chandra Advanced CCD Imaging Spectrometer
AU - Townsley, L. K.
AU - Broos, P. S.
AU - Chartas, G.
AU - Moskalenko, E.
AU - Nousek, J. A.
AU - Pavlov, G. G.
N1 - Funding Information:
Financial support for this effort was provided by Professor Gordon Garmire, Principal Investigator of the ACIS project, via NASA contract NAS8-38252. This work made use of the NASA Astrophysics Data System.
PY - 2002/7/1
Y1 - 2002/7/1
N2 - We have implemented a Monte Carlo algorithm to model and predict the response of various kinds of CCDs to X-ray photons and minimally ionizing particles and have applied this model to the CCDs in the Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer. This algorithm draws on empirical results and predicts the response of all basic types of X-ray CCD devices. It relies on new solutions of the diffusion equation, including recombination, to predict the radial charge cloud distribution in field-free regions of CCDs. By adjusting the size of the charge clouds, we can reproduce the event grade distribution seen in calibration data. Using a model of the channel stops developed here and an insightful treatment of the insulating layer under the gate structure developed at MIT, we are able to reproduce all notable features in ACIS calibration spectra. The simulator is used to reproduce ground and flight calibration data from ACIS, thus confirming its fidelity. It can then be used for a variety of calibration tasks, such as generating spectral response matrices for spectral fitting of astrophysical sources, quantum efficiency estimation, and modeling of photon pile-up.
AB - We have implemented a Monte Carlo algorithm to model and predict the response of various kinds of CCDs to X-ray photons and minimally ionizing particles and have applied this model to the CCDs in the Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer. This algorithm draws on empirical results and predicts the response of all basic types of X-ray CCD devices. It relies on new solutions of the diffusion equation, including recombination, to predict the radial charge cloud distribution in field-free regions of CCDs. By adjusting the size of the charge clouds, we can reproduce the event grade distribution seen in calibration data. Using a model of the channel stops developed here and an insightful treatment of the insulating layer under the gate structure developed at MIT, we are able to reproduce all notable features in ACIS calibration spectra. The simulator is used to reproduce ground and flight calibration data from ACIS, thus confirming its fidelity. It can then be used for a variety of calibration tasks, such as generating spectral response matrices for spectral fitting of astrophysical sources, quantum efficiency estimation, and modeling of photon pile-up.
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U2 - 10.1016/S0168-9002(01)02155-6
DO - 10.1016/S0168-9002(01)02155-6
M3 - Article
AN - SCOPUS:0036645473
SN - 0168-9002
VL - 486
SP - 716
EP - 750
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 - 3
ER -