  HgCdTe detector arrays with a cutoff wavelength of ~10 ${\mu}$m intended for
the NEOCam space mission were subjected to proton beam irradiation at the
University of California Davis Crocker Nuclear Laboratory. Three arrays were
tested - one with 800 $\mu$m substrate intact, one with 30 $\mu$m substrate,
and one completely substrate-removed. The CdZnTe substrate, on which the HgCdTe
detector is grown, has been shown to produce luminescence in shorter wave
HgCdTe arrays that causes elevated signal in non-hit pixels when subjected to
proton irradiation. This testing was conducted to ascertain whether or not full
substrate removal is necessary. At the dark level of the dewar, we detect no
luminescence in non-hit pixels during proton testing for both the
substrate-removed detector array and the array with 30 ${\mu}$m substrate. The
detector array with full 800 ${\mu}$m substrate exhibited substantial
photocurrent for a flux of 103 protons/cm$^2$-s at a beam energy of 18.1 MeV (~
750 e$^-$/s) and 34.4 MeV ($\sim$ 65 e$^-$/s). For the integrated space-like
ambient proton flux level measured by the Spitzer Space Telescope, the
luminescence would be well below the NEOCam dark current requirement of <200
e$^-$/s, but the pattern of luminescence could be problematic, possibly
complicating calibration.

Instrumentation and Detectors;Instrumentation and Methods for Astrophysics