Claudio Gotti (Universita & INFN, Milano-Bicocca (IT))
Experiments searching for rare nuclear events, such as the neutrinoless double beta decay, need to operate for several years in order to reach the required sensitivity. The readout electronics for such systems must guarantee stable operation during the whole data taking phase. Major experiments in the field are CUORE and LUCIFER, both based on macrobolometers and currently under construction underground at the Laboratori Nazionali del Gran Sasso (LNGS) in central Italy. The electronic readout system for these experiments is being designed and built to meet the required stringent specifications on low noise and stability. The power supply system must provide the front-end electronics with very stable operating voltages, and is composed by three items. Commercial AC/DC converters are used to provide a +48 V supply from the mains line. Several low ripple DC/DC converters are used to bring the +48 V to dual ±8 V, ±12 V and ±15 V to the crates housing the electronics. The last and most critical stage is composed by linear power conditioners with low noise (< 0.1ppm, down to 0.1 Hz) and low drift (a few ppm/°C) to provide the detectors and the front-end electronics with the required operating voltages. The output voltages can be set between +/- 3.75 V and +/- 12.5 V in eight steps. The rated current from each output is 4 A. The circuits are protected against failures and shorts at the output by a novel thermal foldback scheme, that dinamically adjusts the maximum output current based on the temperature the output transistor.