LAAPD low temperature performance in X-ray and visible-light detection

The performance of a large area avalanche photodiode (LAAPD) has been investigated for X-ray and visible-light detection as a function of temperature. Energy resolution improves significantly with decreasing temperature down to 0/spl deg/C and, below that value, at a much slower rate, achieving 9.6% for 5.9 keV X-rays at 0/spl deg/C and for a gain of 60. The gain drift with temperature increases with the reverse bias voltage and is almost constant for temperatures above -15/spl deg/C, reaching rates higher than -5% per degrees Celsius, for a bias voltage of 1770 V. Similar results were obtained for X-ray and visible-light detection. LAAPD nonlinearity between X-ray and light gains is less than 2%, even for gains around 300, and decreases with temperature, being less than 0.5% at 0/spl deg/C, for gains up to 200. For X-rays, the minimum detectable energy is about 0.7 keV at operation temperatures around 16/spl deg/C, for gains above 100, decreasing to about 0.3 keV at temperatures less than 0/spl deg/C, for gains above 200.