  Pixelated CdZnTe detectors are a promising imaging-spectrometer for gamma-ray
astrophysics due to their combination of relatively high energy resolution with
room temperature operation negating the need for cryogenic cooling. This
reduces the size, weight, and power requirements for telescope-based radiation
detectors. Nevertheless, operating CdZnTe in orbit will expose it to the harsh
radiation environment of space. This work, therefore, studies the effects of
$61 \ \mathrm{MeV}$ protons on $2 \times 2 \times 1 \ \mathrm{cm}^3$ pixelated
CdZnTe and quantifies proton-induced radiation damage of fluences up to $2.6
\times 10^8 \ \mathrm{p/cm^2}$. In addition, we studied the effects of
irradiation on two separate instruments: one was biased and operational during
irradiation while the other remained unbiased. Following final irradiation, the
$662 \ \mathrm{keV}$ centroid and nominal $1\%$ resolution of the detectors
were degraded to $642.7 \ \mathrm{keV}, 4.9 \% \ ( \mathrm{FWHM})$ and $653.8 \
\mathrm{keV}, 1.75 \% \ (\mathrm{FWHM})$ for the biased and unbiased systems
respectively. We therefore observe a possible bias dependency on proton-induced
radiation damage in CdZnTe. This work also reports on the resulting activation
and recovery of the instrument following room temperature and
$60^{\circ}\mathrm{C}$ annealing.
