1 research outputs found
The Mid-Infrared Instrument for the James Webb Space Telescope, VII: The MIRI Detectors
The MIRI Si:As IBC detector arrays extend the heritage technology from the
Spitzer IRAC arrays to a 1024 x 1024 pixel format. We provide a short
discussion of the principles of operation, design, and performance of the
individual MIRI detectors, in support of a description of their operation in
arrays provided in an accompanying paper (Ressler et al. (2015)). We then
describe modeling of their response. We find that electron diffusion is an
important component of their performance, although it was omitted in previous
models. Our new model will let us optimize the bias voltage while avoiding
avalanche gain. It also predicts the fraction of the IR-active layer that is
depleted (and thus contributes to the quantum efficiency) as signal is
accumulated on the array amplifier. Another set of models accurately predicts
the nonlinearity of the detector-amplifier unit and has guided determination of
the corrections for nonlinearity. Finally, we discuss how diffraction at the
interpixel gaps and total internal reflection can produce the extended
cross-like artifacts around images with these arrays at short wavelengths, ~ 5
microns. The modeling of the behavior of these devices is helping optimize how
we operate them and also providing inputs to the development of the data
pipeline