Temperature dependence of the thin dead layer avalanche photodiode for low energy electron measurements

We have investigated the temperature dependence of the Hamamatsu spl 6815 Avalanche Photodiode (APD) response, when used as an low energy electron detector, over the temperature range from -9 to 30∘C. In order to make precise measurements, relevant to the particles of interest, electrons were actually used to calibrate the APD response. The gain variation over the temperature was -1.2%/K at 10∘C for a nominal bias voltage. Although a slight dead layer effect was found, the linearity of the response was excellent over all measured temperatures, and the variation of the energy resolution was acceptably small to maintain good performance. The temperature effects can be readily canceled out with an active bias voltage control based on the ambient temperature so long as the internal gain is maintained between 15 and 20.