  MOONS is a multi-object spectrograph for the ESO VLT covering a simultaneous
wavelength range of 0.6-1.8 microns using approximately 1000 fibres. It uses
four Teledyne Imaging Systems H4RG-15 4K x 4K detectors with 2.5 $\mu$m cut-off
material for the two longer wavebands (YJ and H). Since the spectrographs
utilize an extremely fast modified Schmidt camera design, then the detectors
are situated in the optical beam and hence required the development of a novel
64- channel cryogenic differential cryogenic preamplifier, minimized for
optical footprint which will be reported on. We have operated the Engineering
Grade H4RG detector at a range of temperatures from 90K to 40K and we will
report on the advantages of the lower operational temperature. We have
completed a full persistence analysis and are able to model it reasonably well
and will offer a correction for it in our data pipeline. We have also
configured the detector for use with both unbuffered and buffered outputs and
report on the differences in performance between the two output types. We have
also seen some programming issues with the detector type and will report on our
work-around for this, we will also describe the use of the column-deselect
feature and row skipping to minimize the effects of PEDs. We have also measured
charge injection per read and report on this, likewise we have also measured
the inter-pixel capacitance in different regions of the detector. We will
present all these results together with a summary of the complete performance
characteristics of this detector family.
