Abstract
Luminescent bolometers are double-readout devices able to measure simultaneously the phonon and the light yields after a particle interaction in the detector. This operation allows in some cases to tag the type of the interacting quantum, crucial issue for background control in rare event experiments such as the search for neutrinoless double beta decay and for interactions of particle dark matter candidates. The light detectors used in the LUCIFER and LUMINEU searches (projects aiming at the study of the double beta interesting candidates 82Se and 100Mo using ZnSe and ZnMoO4 scintillating bolometers) consist of hyper-pure Ge thin slabs equipped with NTD thermistors. A substantial sensitivity improvement of the Ge light detectors can be obtained applying a proper anti-reflective coatings on the Ge side exposed to the luminescent bolometer. The present paper deals with the investigation of this aspect, proving and quantifying the positive effect of a SiO2 and a SiO coating and setting the experimental bases for future tests of other coating materials. The results confirm that an appropriate coating procedure helps in improving the sensitivity of bolometric light detectors by an important factor (in the range 20% – 35%) and needs to be included in the recipe for the development of an optimized radio-pure scintillating bolometer.
Highlights
Introduction and motivation1.1 Consideration on the coating effectThe simplest form of anti-reflective coating is based on the so-called index matching
It is confirmed that the SiO2 coating gives reproducible positive effects on the light collection efficiency, which prevail over any other possible systematic factors that could simulate or fade this result
The measurements were performed at very low temperatures and in conditions very similar to those in which scintillating bolometers normally operate
Summary
The simplest form of anti-reflective coating is based on the so-called index matching. The materials that we have deposited are SiO2 [4] and SiO The former has a refractive index of 1.54 in crystalline form (quartz) and 1.45 in amorphous form (fused silica), while for the latter the refractive index is 2.48, at room temperature and at 632 nm. These values lead to calculate an absorbed fraction of 64.5% and 63.1% for crystalline and amorphous SiO2 respectively, which corresponds to. In order to get a redundant confirmation of the results and to overcome inevitable small side asymmetries in the detector configuration, more bolometers of each type have been realized
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
