Vibrational and thermal noise reduction for cryogenic detectors

In this paper we present the excellent results obtained by mechanical decoupling of our thermal detectors from the cryostat. The starting point of this work is the necessity to improve the performances of thermal detectors and, besides, to eliminate the non-constant noise resulting from the overall cryogenic facility; this second point results to be crucial for rare-events experiments and the fundamental task for Dark Matter search. Tested on our bolometer, consisting of a 750 g tellurium oxide absorber coupled with an NTD thermistor and operated at similar to 9 mK in an Oxford 200 dilution refrigerator, this powerful technique can, moreover, provide advantages for a large variety of thermal detectors. A good energy resolution of 3.9 keV FWHM was obtained for 2.615 MeV gamma-rays. The 4.2 keV average FWHM resolution for the 5407 keV Po-210 alpha decay line is the best ever obtained for alpha-particles with any type of detector. (C) 2000 Elsevier Science B.V. All rights reserved.