  We present the design, construction, and performance of a facility for the
characterization of Silicon Avalanche Photodiodes in the operating temperature
range between -2 $^\circ$C and 25 $^\circ$C. The system can simultaneously
measure up to 24 photo-detectors, in a completely automatic way, within one day
of operations. The measured data for each sensor are: the internal gain as a
function of the bias voltage and temperature, the gain variation with respect
to the bias voltage, and the dark current as a function of the gain. The
systematic uncertainties have been evaluated during the commissioning of the
system to be of the order of 1%. This paper describes in detail the facility
design and layout, and the procedure employed to characterize the sensors. The
results obtained from the measurement of the 380 Avalanche Photodiodes of the
CLAS12-Forward Tagger calorimeter detector are then reported, as the first
example of the massive usage of the facility.
