Characterization of LN2 cooled LAAPDs for single photon counting applications

Large Area Avalanche Photo Diodes (LAAPDs) operated near liquid nitrogen temperatures are one of the technologies currently under investigation for the detection of low fluorescence photon rates produced in the laser spectroscopy experiment SPECTRAP at GSI. The measurement of hyperfine transitions in highly charged ions requires single photon detection capabilities at various wavelengths from the UV to the near infrared. With high quantum efficiencies (QE) LAAPDs are a possible candidate for measurements of the hyperfine transitions e.g. in hydrogen like lead ( 207 Pb 81+ ). To characterize the temperature dependent dark current, the gain and the signal to noise ratio of the detectors as a function of temperature and operating voltage, a LN2 cooled cryogenic test bed has been set up at the nuclear physics institute in Munster.