Innovative methods for background rejection in next-generation neutrinoless double beta decay bolometric experiments

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A90263%2F23%3A00374015" target="_blank" >RIV/68407700:90263/23:00374015 - isvavai.cz</a>

Result on the web

<a href="https://theses.hal.science/tel-04327156v1" target="_blank" >https://theses.hal.science/tel-04327156v1</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Innovative methods for background rejection in next-generation neutrinoless double beta decay bolometric experiments

Original language description

The search for neutrinoless double beta decay (0ν2β) is a major challenge in contemporary physics, as its observation would demonstrate that the neutrino is a Majorana particle. The half-life of the process being related to the effective Majorana mass mββ, it would also provide a measure of the neutrino mass scale and information on its mass hierarchy. The next-generation experiment CUPID aims to reach a sensitivity high enough to explore completely the region of possible values for mββ in the case of the inverted hierarchy. It will use scintillating bolometers made of a Li₂MoO₄ (LMO) crystal, containing ¹⁰⁰Mo as the 2β candidate isotope, coupled to a Ge bolometric light detector. Thanks to the dual light/heat readout, CUPID will be able to reject the background due to α particles, which is the main source limiting the sensitivity of CUORE, its predecessor, and aims to achieve a background level of 10⁻⁴ counts/kg/keV/year (ckky) in the region of interest (ROI). However, if the 0ν2β still eludes us after CUPID, we will have to push the background reduction even further to explore the spectrum of values for mββ possible in the case of the normal mass hierarchy. It is in this context that BINGO (Bi-Isotope 0ν2β Next Generation Observatory) and the work of this thesis lay. This project aims to test innovative methods for achieving a background of 10⁻⁵ ckky in the ROI of ¹⁰⁰Mo but also of ¹3⁰Te, respectively embedded in LMO and TeO₂ crystals. Firstly, an innovative assembly of bolometers reducing the amount of passive material around the detectors has been developed and validated. Secondly, R&D on implementing a cryogenic active veto composed of scintillators around the volume containing the bolometers was done to reject external γ events by coincidence. A study of potential candidates led to the selection of the BGO for the material. A cryogenic test of a prototype veto module containing two BGOs is also reported in this thesis. Other light collection measurements have also been done at room temperature. Finally, to use TeO₂ crystals as scintillating bolometers, it is necessary to boost the performance of the light detectors. To achieve this goal, BINGO will operate light detectors using the Neganov-Trofimov-Luke (NTL) effect to amplify the signal. An R&D campaign has been conducted to test a new method for depositing aluminum electrodes and different electrode geometries.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

10304 - Nuclear physics

Project

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Continuities

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Publication year

2023

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů