  The Ultra-Fast Flash Observatory (UFFO) pathfinder is a space mission devoted
to the measurement of Gamma-Ray Bursts (GRBs), especially their early light
curves which will give crucial information on the progenitor stars and central
engines of the GRBs. It consists of two instruments: the UFFO Burst Alert &
Trigger telescope (UBAT) for the detection of GRB locations and the Slewing
Mirror Telescope (SMT) for the UV/optical afterglow observations, upon
triggering by UBAT. The UBAT employs a coded-mask {\gamma}/X-ray camera with a
wide field of view (FOV), and is comprised of three parts: a coded mask, a
hopper, and a detector module (DM). The UBAT DM consists of a LYSO scintillator
crystal array, multi-anode photo multipliers, and analog and digital readout
electronics. We present here the design and fabrication of the UBAT DM, as well
as its preliminary test results.
