A new algorithm is presented to discriminate reconstructed hadronic decays of tau leptons (? h) that originate from genuine tau leptons in the CMS detector against ? h candidates that originate from quark or gluon jets, electrons, or muons. The algorithm inputs information from all reconstructed particles in the vicinity of a ? h candidate and employs a deep neural network with convolutional layers to efficiently process the inputs. This algorithm leads to a significantly improved performance compared with the previously used one. For example, the efficiency for a genuine ? h to pass the discriminator against jets increases by 10-30% for a given efficiency for quark and gluon jets. Furthermore, a more efficient ? h reconstruction is introduced that incorporates additional hadronic decay modes. The superior performance of the new algorithm to discriminate against jets, electrons, and muons and the improved ? h reconstruction method are validated with LHC proton-proton collision data at s = 13 TeV.

A scintillating bolometer based on a large cubic Li2100MoO4 crystal (45 mm side) and a Ge wafer (scintillation detector) has been operated in the CROSS cryogenic facility at the Canfranc underground laboratory in Spain. The dual-readout detector is a prototype of the technology that will be used in the next-generation 0?2? experiment CUPID . The measurements were performed at 18 and 12 mK temperature in a pulse tube dilution refrigerator. This setup utilizes the same technology as the CUORE cryostat that will host CUPID and so represents an accurate estimation of the expected performance. The Li2100MoO4 bolometer shows a high energy resolution of 6 keV FWHM at the 2615 keV ? line. The detection of scintillation light for each event triggered by the Li2100MoO4 bolometer allowed for a full separation (~8?) between ?(?) and ? events above 2 MeV . The Li2100MoO4 crystal also shows a high internal radiopurity with 228Th and 226Ra activities of less than 3 and 8 ?Bq/kg, respectively. Taking also into account the advantage of a more compact and massive detector array, which can be made of cubic-shaped crystals (compared to the cylindrical ones), this test demonstrates the great potential of cubic Li2100MoO4 scintillating bolometers for high-sensitivity searches for the 100Mo 0?2? decay in CROSS and CUPID projects.

We have developed and tested a new way of coupling bolometric light detectors to scintillating crystal bolometers based upon simply resting the light detector on the crystal surface, held in position only by gravity. This straightforward mounting results in three important improvements: (1) it decreases the amount of non-active materials needed to assemble the detector, (2) it substantially increases the light collection efficiency by minimizing the light losses induced by the mounting structure, (3) and it enhances the thermal signal induced in the light detector thanks to the extremely weak thermal link to the thermal bath.We tested this new technique with a 16 cm(2) Ge light detector with thermistor readout sitting on the surface of a large TeO2 bolometer. The light collection efficiency was increased by greater than 50% compared to previously tested alternative mountings. We obtained a baseline energy resolution on the light detector of 20 eV RMS that, together with increased light collection, enabled us to obtain the best alpha vs beta/gamma discrimination ever obtained with massive TeO2 crystals. At the same time we achieved rise and decay times of 0.8 and 1.6 ms, respectively. This superb performance meets all of the requirements for the CUPID (CUORE Upgrade with Particle IDentification) experiment, which is a 1-ton scintillating bolometer follow up to CUORE.