  The MicroBooNE detector, to be located on axis in the Booster Neutrino
Beamline (BNB) at the Fermi National Accelerator Laboratory (Fermilab),
consists of two main components: a large liquid argon time projection chamber
(LArTPC), and a light collection system. Thirty 8-inch diameter Hamamatsu
R5912-02mod cryogenic photomultiplier tubes (PMTs) will detect the
scintillation light generated in the liquid argon (LAr). This article first
describes the MicroBooNE PMT performance test procedures, including how the
light collection system functions in the detector, and the design of the PMT
base. The design of the cryogenic test stand is then discussed, and finally the
results of the cryogenic tests are reported.
