The temperature stabilization system of CUORICINO: an array of macro bolometers

We present our circuit solution for the implementation of a very simple temperature stabilization system of an array of 62 large mass bolometric detectors, CUORICINO. The implemented instrument exploits one of the front-end channels to close the feedback loop between a thermistor and a heather, both of them located on the detector holder in the refrigerating system. A very compact layout was developed that avoids any possible presence of EMI interference, which would otherwise be introduced if a commercial instrument were adopted. The stabilized temperature is obtained exploiting the offset correcting circuit of the remotely programmable front-end channel to autogenerate the reference operating point for the feedback loop. Thanks to the adopted configuration, the instability of the cryogenic apparatus, which induced a drift corresponding to about 50 keV/day, was reduced to less than about 0.5 keV/day. To model the system behavior, we have reformulated the bolometer theory of operation using the concept of a feedback network. The obtained results will be shown.