Engineering topics

Vacri, M. L. Di

Publications and source records attributed to Vacri, M. L. Di.

5 records

DOE OSTI2020

Reflectivity and PDE of VUV4 Hamamatsu SiPMs in liquid xenon

Considering reflective properties of materials and photodetection efficiency (PDE) of photodetectors is important for optimizing energy resolution and sensitivity of the next generation neutrinoless double beta decay, direct detection dark matter, and neutrino oscillation experiments that will use noble liquid gases, such as nEXO, DARWIN, DarkSide-20k, and DUNE . Little information is currently available about reflectivity and PDE in liquid noble gases, because such measurements are difficult to conduct in a cryogenic environment and at short enough wavelengths. Here we report a measurement of specular reflectivity and relative PDE of Hamamatsu VUV4 silicon photomultipliers (SiPMs) with 50 μ m micro-cells conducted with xenon scintillation light ( ~ 175 nm) in liquid xenon. The specular reflectivity at 15 o incidence of three samples of VUV4 SiPMs is found to be 30.4 ± 1.4%, 28.6 ± 1.3%, and 28.0 ± 1.3%, respectively. The PDE at normal incidence differs by ± 8% (standard deviation) among the three devices. The angular dependence of the reflectivity and PDE was further measured for one of the SiPMs. Both the reflectivity and PDE decrease as the angle of incidence increases. This is the first measurement of an angular dependence of PDE and reflectivity of a SiPM in liquid xenon.

47 OTHER INSTRUMENTATION↗

DOE OSTI2019

First results from the CUORE experiment

CUORE (Cryogenic Underground Observatory for Rare Events) is a ton-scale experiment aiming to the search of neutrino-less double beta decay in 130 Te with a projected sensitivity on the Majorana effective mass close to the inverted hierarchy region. The CUORE detector consists of a segmented array of 988 TeO 2 bolometers, organized in 19 towers and operated at a temperature of about 10 mK thanks to a custom cryogenic system which, besides the uncommon scale, observes several constraints from the radio-purity of the materials to the mechanical decoupling of the cooling systems. The successful commissioning of the CUORE cryogenic system has been completed early in 2016 and represents an outstanding achievement by itself. The installation of the detector proceeded along 2016 followed by the cooldown to base temperature at the beginning of 2017. The CUORE detector is now operational and has been taking science data since Spring 2017. With the first ~3 weeks of collected data, we present here the most stringent constraint on the 130 Te half-live for the neutrino-less double beta decay.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2019

Initial performance of the CUORE detector

CUORE, the Cryogenic Underground Observatory for Rare Events, is an experiment searching for the neutrinoless double-beta decay of 130 Te. The first CUORE dataset was acquired in May and June 2017 and consisted of 10.6 kg-yr of TeO 2 exposure, with several days of calibration data before and after the physics dataset. We discuss here the initial performance of the CUORE detector and cryostat in this first dataset.

47 OTHER INSTRUMENTATION↗

DOE OSTI2019

Simulation of charge readout with segmented tiles in nEXO

nEXO is a proposed experiment to search for the neutrino-less double beta decay (0νββ) of 136 Xe in a tonne-scale liquid xenon time projection chamber (TPC). The nEXO TPC will be equipped with charge collection tiles to form the anode. In this work, the charge reconstruction performance of this anode design is studied with a dedicated simulation package. A multi-variate method and a deep neural network are developed to distinguish simulated 0νββ signals from backgrounds arising from trace levels of natural radioactivity in the detector materials. These simulations indicate that the nEXO TPC with charge-collection tiles shows promising capability to discriminate the 0νββ signal from backgrounds. Furthermore, the estimated half-life sensitivity for 0νββ decay is improved by 20 32)% with the multi-variate (deep neural network) methods considered here, e sensitivity estimated in the nEXO pre-conceptual design report.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2019

Double-beta decay of $^{130}\hbox {Te}$ to the first $0^+$ excited state of $^{130}\hbox {Xe}$ with CUORE-0

We report on a search for double beta decay of 130 Te to the first 0 + excited state of 130 Xe using a 9.8kg·yr exposure of 130 Te collected with the CUORE-0 experiment. In this work we exploit different topologies of coincident events to search for both the neutrinoless and two-neutrino double beta decay modes. We find no evidence for either mode and place lower bounds on the half-lives: $T_{0_1^+}^{0ν}$ > 7.9·10 23 yr and $T_{0_1^+}^{2ν}$ > 2.4·10 23 yr (90%CL). Combining our results with those obtained by the CUORICINO experiment, we achieve the most stringent constraints available for these processes: $T_{0_1^+}^{0ν}$ > 1.4·10 24 yr and $T_{0_1^+}^{2ν}$ > 2.5·10 23 yr (90%CL).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗