  The effect of 30 keV Ga^+ ion beam irradiation on the low-temperature
photoluminescence from a single crystal of the hybrid organic-inorganic
perovskite MAPbBr3 is presented for the first time. The irradiation leads to
the suppression of the crystal's excitonic luminescence starting from the dose
of 10^14/cm2. However, its integral luminescence does not drop up to the doses
of two orders of magnitude higher. Further increase of the irradiation dose
starts to affect the integral luminescence and causes the crystal to sputter.
The spatial resolution of modification by the ion beam found in the experiment
is no worse than 50 {\mu}m. The theoretical resolution limit estimated by
Monte-Carlo modeling using SRIM is three orders of magnitude lower. This work
paves the way for the design of devices based on the spatial modulation of
perovskite's excitonic properties or direct focused ion beam writing.
