Avalanche photodiodes ( APDs ) are promising light sensor for various fields of experimental physics .
It has been argued , however , that variation of APD gain with temperature could be a serious problem preventing APDs from replacing traditional photomultiplier tubes ( PMTs ) in some applications .
Here we develop an active gain-control system to keep the APD gain stable under moderate temperature variations .
As a performance demonstration of the proposed system , we have tested the response of a scintillation photon detector consisting of a 5 \times 5 mm ^ { 2 } reverse-type APD optically coupled with a CsI ( Tl ) crystal .
We show that the APD gain was successfully controlled under a temperature variation of \Delta T = 20 ^ { \circ } C , within a time-cycle of 6000 sec .
The best FWHM energy resolution of 6.1 \pm 0.2 \% was obtained for 662 keV \gamma -rays , and the energy threshold was as low as 6.5 keV , by integrating data from +20 ^ { \circ } C - 0 ^ { \circ } C cycles .
The corresponding values for - 20 ^ { \circ } C - 0 ^ { \circ } C cycles were 6.9 \pm 0.2 \% and 5.2 keV , respectively .
These results are comparable , or only slightly worse than that obtained at a fixed temperature .
Our results suggest new potential uses for APDs in various space researches and nuclear physics .
As examples , we briefly introduce the NeXT and Cute-1.7 satellite missions that will carry the APDs as scientific instruments for the first time .