Towards BINGO : development of advanced background reduction technologies for neutrinoless double-beta decay bolometric experiments

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A90263%2F25%3A00390829" target="_blank" >RIV/68407700:90263/25:00390829 - isvavai.cz</a>

Result on the web

<a href="https://theses.hal.science/tel-05240476v1" target="_blank" >https://theses.hal.science/tel-05240476v1</a>

DOI - Digital Object Identifier

—

Result language

angličtina

Original language name

Towards BINGO : development of advanced background reduction technologies for neutrinoless double-beta decay bolometric experiments

Original language description

Neutrinoless double-beta decay (0ν2β) is a key process in the search for Majorana neutrinos. Its observation would confirm the violation of lepton number conservation, demonstrating that neutrinos are their own antiparticles, and provide crucial insight into the absolute neutrino mass scale and hierarchy. The CUPID (CUORE Upgrade with Particle ID) experiment aims to achieve the sensitivity required to probe the inverted hierarchy region of the neutrino mass pattern and a significant fraction of the normal (or direct) one. It will employ an array of scintillating bolometers composed of Li₂MoO₄ (LMO) crystals enriched in ¹⁰⁰Mo, coupled with Ge bolometric light detectors. This dual heat-light readout enables an efficient rejection of the α background, which currently limit the sensitivity of its predecessor, CUORE. CUPID aims to reach an unprecedented background index of 10⁻⁴ counts/kg/keV/year (ckky) in the region of interest (ROI) and to establish the technology required for a future ton-scale bolometric 0ν2β experiment. Beyond CUPID, further sensitivity improvements are necessary to probe deeper the normal hierarchy region. The BINGO (Bi-Isotope 0ν2β Next Generation Observatory) project, the focus of this thesis, introduces novel strategies to reduce background levels to 10⁻⁵ ckky for the simultaneous study of ¹⁰⁰Mo and ¹3⁰Te isotopes. The major innovation in BINGO is the development of an innovative detector assembly that minimizes passive materials surrounding the detectors, thereby reducing background contamination from surface radioactivity. The assembly was tested in cryogenic measurements, demonstrating good mechanical stability and bolometric performance. Additionally, a cryogenic active veto system was designed to tag and reject external γ radiation. A prototype veto module, consisting of four BGO crystals, was tested in cryogenic conditions, confirming the feasibility of this approach. Complementary room-temperature light collection measurements were also conducted to optimize the light yield using different reflecting materials. Finally, BINGO explores advancements in light detection. TeO₂ crystals, a leading choice for bolometric calorimetry, require improved light collection to operate as luminiscent bolometers. This challenge is addressed through the implementation of Neganov-Trofimov-Luke (NTL) light detectors, which amplify scintillation signals to enhance particle identification and reject background events. This thesis presents R&D on detector fabrication, exploring various electrode geometries to maximize NTL gain. The results of this work contribute directly to the development of the MINI-BINGO demonstrator, a key step toward scaling up the technology. In addition, this thesis has given a fundamental contribution to the demonstrator’s design, the development of passive cryostat shielding, and its role as a proof-of-concept for a future ton-scale 0ν2β experiment. The transition from a demonstrator to a large-scale experiment is discussed, with a focus on the integration of BINGO into the CUORE cryostat and the implications for next-generation searches.

Czech name

—

Czech description

—

Type

O - Miscellaneous

CEP classification

—

OECD FORD branch

10304 - Nuclear physics

Project

—

Continuities

—

Publication year

2025

Confidentiality

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