A Thermal Model for Low Temperature TeO 2 Calorimeters

In this paper, we present the application of a simplified thermal model in order to extract some of the fundamental parameters needed to understand the response function of low-temperature calorimeters consisting of TeO 2 crystals read-out by neutron transmutation doped (NTD) thermistors operated at temperatures T∼ 10 mK. To this aim, four detectors were hosted in two different holders, one made of copper and the other made of Stratasys VeroClear TM, a 3D-printed plastic material very similar to acrylic. The static characterization of the detectors through the analysis of their load curves at different temperatures, guided by the thermal model, enabled the identification of the main thermal link to the heat sink of the two systems: the glue between the crystal and the copper frame (scaling as T3) for the detectors in the copper holder, and the NTD gold read-out wires (scaling as T2.5) for the detectors in the plastic holder. As a subdominant contribution, we could also extract the electron–phonon decoupling characteristic of our NTDs, described by a thermal conductance scaling as T4.