arXiv subjects

S. Marnieros

Publications and source records attributed to S. Marnieros.

At least 19 recordsLinked to original sources

arXiv2026

The CROSS experiment: detector construction, background projection, and sensitivity to $^{100}$Mo $0\nu2\beta$ decay

The CROSS experiment to search for neutrinoless double-beta ($0\nu2\beta$) decay in $^{100}$Mo with the help of an array of scintillating cryogenic calorimeters, containing 4.9 kg of $^{100}$Mo, has been ongoing in a low-background setup at the Canfranc underground laboratory (Spain) since mid-November 2025. In this paper, we present the construction of the CROSS detector and the description of Geant4-based Monte Carlo simulations of expected background in the region of interest. The simulations predict the background index in a 100-keV-wide interval centered at the $Q$-value of $^{100}$Mo (3034 keV) on the level of 3.2(5) $\times$ 10$^{-3}$ cnts/keV/kg/yr. Taking into account an 18% deadtime induced by the muon veto cut and a typical 90% duty cycle of the facility, such background level would allow to reach the world-leading sensitivity to $^{100}$Mo $0\nu2\beta$ decay (lim $T_{1/2} \sim 4 \times 10^{24}$ yr) in 1 year of data taking. Considering conservatively a factor 3 (10) worse background index due to unpredictable radioactive contamination of construction materials and/or detector performance, a 2-yr-long operation of the CROSS array would be still compatible with the best (competitive) sensitivity to $0\nu2\beta$ decay in $^{100}$Mo.

physics.ins-det↗

arXiv2026

Low Energy Phonon Bursts Created By Fast Neutron Damage

Solid state athermal phonon calorimeters used in the search for low mass dark matter or coherent neutrino-nucleus interactions have long observed a large excess of events below several hundred eV. The relaxation of damage created by the interaction of fast cosmic ray neutrons with the detector has been proposed as a source of these excess events. By comparing neutron exposed detectors to control detectors, we report the first measurement of phonon bursts caused by damage created by fast neutrons. Differences in the spectral shape, the rate dependence on thermal history, and the observed spectral rate scaled to the neutron exposure between irradiated and control detectors suggest that our observed LEE backgrounds are not dominated by neutron damage-induced phonon bursts.

physics.ins-det↗

arXiv2025

Observation of two nuclear recoil peaks induced by neutron capture on Al2O3

We report the observation of two nuclear recoil peaks induced by neutron capture on aluminum in a cryogenic Al$_2$O$_3$ detector developed by the NUCLEUS collaboration for the detection of reactor neutrinos via coherent elastic neutrino-nucleus (CEvNS) process. Data collected at the Technical University of Munich in 2024 with a $^{252}$Cf source reveal a main recoil line at 1145 eV from single-$\gamma$ de-excitation of $^{28}$Al and a newly observed structure near 575 eV originating from several two-$\gamma$ cascades. The latter constitutes the first direct measurement of a nuclear recoil line induced by multi-$\gamma$ cascades. It is predicted by our simulations when the recoiling nucleus has time to stop before the emission of the next $\gamma$-ray in the cascade. These results demonstrate the potential performance of the CRAB (Calibration Recoil for Accurate Bolometry) method for in situ nuclear recoil calibration and highlight the importance of accurately modeling recoil stopping and nuclear de-excitation times in cryogenic detectors of CEvNS and dark matter interactions.

physics.ins-det↗

arXiv2025

Muon veto system for the CROSS double-beta decay search experiment

In preparation to the CROSS experiment at the Canfranc underground laboratory (Spain) $-$ aiming to search for neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{100}$Mo using low-temperature detectors with heat-scintillation readout $-$ we report on development of a dedicated muon veto system. The need for the muon veto in CROSS is caused by a comparatively high residual cosmic muon flux at the experimental site ($\sim$20 $\mu$/m$^2$/h), being a dominant background in the region of interest (ROI) at $\sim$3 MeV. Thus, we installed the muon veto system around the CROSS low-background setup, forming four lateral, one top, and four bottom sectors. In this paper we describe the design, construction and operation of the CROSS muon veto system, as well as its optimization and validation by comparing dedicated Monte Carlo (MC) simulations of muons with low-temperature measurements in the setup. We demonstrate a stable operation of the veto system with the average trigger rates compatible with MC simulations. Also, we investigated two muon trigger logics based on coincidences with either 2 sectors or a single sector of the veto. The MC study shows that, in combination with the multiplicity cut of thermal detectors, these trigger logics allow to reject 99.2\% and 99.7\% of muon-induced events in the ROI, respectively. Despite a comparatively high dead time ($\sim$18\%) introduced by coincidences with any of nine sectors of the veto $-$ the adopted strategy $-$ the muon-induced background in the ROI of the CROSS experiment can be reduced down to $\sim$2 $\times 10^{-3}$ cnts/keV/kg/yr, i.e., an acceptable level compatible with a high-sensitivity $0\nu\beta\beta$ decay search foreseen in CROSS.

physics.ins-det↗

arXiv2025

Cryogenic light detectors with thermal signal amplification for $0\nu\beta\beta$ search experiments

As a step towards the realization of cryogenic-detector experiments to search for neutrinoless double-beta decay (such as CROSS, BINGO, and CUPID), we investigated a batch of 10 Ge light detectors (LDs) assisted by Neganov-Trofimov-Luke (NTL) signal amplification. Each LD was assembled with a large cubic light-emitting crystal (45 mm side) using the recently developed CROSS mechanical structure. The detector array was operated at milli-Kelvin temperatures in a pulse-tube cryostat at the Canfranc underground laboratory in Spain. We achieved good performance with scintillating bolometers from CROSS, made of Li$_{2}$$^{100}$MoO$_4$ crystals and used as reference detectors of the setup, and with all LDs tested (except for a single device that encountered an electronics issue). No leakage current was observed for 8 LDs with an electrode bias up to 100 V. Operating the LDs at an 80 V electrode bias applied in parallel, we obtained a gain of around 9 in the signal-to-noise ratio of these devices, allowing us to achieve a baseline noise RMS of $O$(10 eV). Thanks to the strong current polarization of the temperature sensors, the time response of the devices was reduced to around half a millisecond in rise time. The achieved performance of the LDs was extrapolated via simulations of pile-up rejection capability for several configurations of the CUPID detector structure. Despite the sub-optimal noise conditions of the LDs (particularly at high frequencies), we demonstrated that the NTL technology provides a viable solution for background reduction in CUPID.

physics.ins-det↗

arXiv2025

The CRAB facility at the TU Wien TRIGA reactor: status and related physics program

The CRAB (Calibrated nuclear Recoils for Accurate Bolometry) project aims to precisely characterize the response of cryogenic detectors to sub-keV nuclear recoils of direct interest for coherent neutrino-nucleus scattering and dark matter search experiments. The CRAB method relies on the radiative capture of thermal neutrons in the target detector, resulting in a nuclear recoil with a well-defined energy. We present a new experimental setup installed at the TRIGA Mark-II reactor at Atominstitut (Vienna), providing a low intensity beam of thermal neutrons sent to the target cryogenic detector mounted inside a wet dilution refrigerator Kelvinox 100. A crown of BaF$_2$ detectors installed outside the dewar enables coincident detection of the high-energy $\gamma$ escaping the target crystal after neutron capture. After the presentation of all components of the setup we report the analysis of first commissioning data with a CaWO$_4$ detector of the \NUCLEUS experiment. They show stable operation of the cryostat and detectors on a week-scale. Due to an energy resolution currently limited to 20 eV we use neutron beam induced events at high energy, in the 10 to 100 keV range, to demonstrate the excellent agreement between the data and simulation and the accurate understanding of external background. Thanks to these data we also propose an updated decay scheme of the low-lying excited states of $^{187}$W. Finally, we present the first evidence of neutron-capture induced coincidences between $\gamma$-detectors and a cryogenic detector. These promising results pave the way for an extensive physics program with various detector materials, like CaWO$_4$, Al$_2$O$_3$, Ge and Si.

physics.ins-det↗

arXiv2024

Precise $^{113}$Cd $\beta$ decay spectral shape measurement and interpretation in terms of possible $g_A$ quenching

Highly forbidden $\beta$ decays provide a sensitive test to nuclear models in a regime in which the decay goes through high spin-multipole states, similar to the neutrinoless double-$\beta$ decay process. There are only 3 nuclei ($^{50}$V, $^{113}$Cd, $^{115}$In) which undergo a $4^{\rm th}$ forbidden non-unique $\beta$ decay. In this work, we compare the experimental $^{113}$Cd spectrum to theoretical spectral shapes in the framework of the spectrum-shape method. We measured with high precision, with the lowest energy threshold and the best energy resolution ever, the $\beta$ spectrum of $^{113}$Cd embedded in a 0.43 kg CdWO$_4$ crystal, operated over 26 days as a bolometer at low temperature in the Canfranc underground laboratory (Spain). We performed a Bayesian fit of the experimental data to three nuclear models (IBFM-2, MQPM and NSM) allowing the reconstruction of the spectral shape as well as the half-life. The fit has two free parameters, one of which is the effective weak axial-vector coupling constant, $g_A^{\text{eff}}$, which resulted in $g_A^{\text{eff}}$ between 1.0 and 1.2, compatible with a possible quenching. Based on the fit, we measured the half-life of the $^{113}$Cd $\beta$ decay including systematic uncertainties as $7.73^{+0.60}_{-0.57} \times 10^{15}$ yr, in agreement with the previous experiments. These results represent a significant step towards a better understanding of low-energy nuclear processes.

nucl-ex↗

arXiv2024

Development of large-volume $^{130}$TeO$_2$ bolometers for the CROSS $2\beta$ decay search experiment

We report on the development of thermal detectors based on large-size tellurium dioxide crystals (45x45x45 mm), containing tellurium enriched in $^{130}$Te to about 91%, for the CROSS double-beta decay experiment. A powder used for the crystals growth was additionally purified by the directional solidification method, resulting in the reduction of the concentration of impurities by a factor 10, to a few ppm of the total concentration of residual elements (the main impurity is Fe). The purest part of the ingot (the first ~200 mm, about 80% of the total length of the cylindrical part of the ingot) was determined by scanning segregation profiles of impurities and used for the $^{130}$TeO$_2$ powder production with no evidence of re-contamination. The crystal growth was verified with precursors produced from powder with natural Te isotopic composition, and two small-size (20x20x10 mm) samples were tested at a sea-level laboratory showing high bolometric and spectrometric performance together with acceptable $^{210}$Po content (below 10 mBq/kg). This growth method was then applied for the production of six large cubic $^{130}$TeO$_2$ crystals and 4 of them were taken randomly to be characterized at the Canfranc underground laboratory, in the CROSS-dedicated low-background cryogenic facility. Two $^{130}$TeO$_2$ samples were coated with a thin, $O$(100 nm), metal film in form of Al layer (on 4 sides) or AlPd grid (on a single side) to investigate the possibility to tag surface events by pulse-shape discrimination. Similarly to the small natural precursors, large-volume $^{130}$TeO$_2$ bolometers show high performance and even better internal purity ($^{210}$Po activity $\sim$ 1 mBq/kg, while activities of $^{228}$Th and $^{226}$Ra are below 0.01 mBq/kg), satisfying requirements for the CROSS and, potentially, next-generation experiments.

physics.ins-det↗

arXiv2024

A novel mechanical design of a bolometric array for the CROSS double-beta decay experiment

The CROSS experiment will search for neutrinoless double-beta decay using a specific mechanical structure to hold thermal detectors. The design of the structure was tuned to minimize the background contribution, keeping an optimal detector performance. A single module of the structure holds two scintillating bolometers (with a crystal size of 45x45x45 mm and a Ge slab facing the crystal's upper side) in the Cu frame, allowing for a modular construction of a large-scale array. Two designs are released: the initial $Thick$ version contains around 15% of Cu over the crystal mass (lithium molybdate, LMO), while this ratio is reduced to ~6% in a finer ($Slim$) design. Both designs were tested extensively at aboveground (IJCLab, France) and underground (LSC, Spain) laboratories. In particular, at LSC we used a pulse-tube-based CROSS facility to operate a 6-crystal array of LMOs enriched/depleted in $^{100}$Mo. The tested LMOs show high spectrometric performance in both designs; notably, the measured energy resolution is 5--7 keV FWHM at 2615 keV $\gamma$s, nearby the Q-value of $^{100}$Mo (3034 keV). Due to the absence of a reflective cavity around LMOs, a low scintillation signal is detected by Ge bolometers: ~0.3 keV (150 photons) for 1-MeV $\gamma$($\beta$) LMO-event. Despite that, an acceptable separation between $\alpha$ and $\gamma$($\beta$) events is achieved with most devices. The highest efficiency is reached with light detectors in the $Thick$ design thanks to a lower baseline noise width (0.05--0.09 keV RMS) when compared to that obtained in the $Slim$ version (0.10--0.35 keV RMS). Given the pivotal role of bolometric photodetectors for particle identification and random coincidences rejection, we will use the structure here described with upgraded light detectors, featuring thermal signal amplification via the Neganov-Trofimov-Luke effect, as also demonstrated in the present work.

physics.ins-det↗

arXiv2024

Searching for Beyond the Standard Model physics using the improved description of $^{100}$Mo $2\nu\beta\beta$ decay spectral shape with CUPID-Mo

The current experiments searching for neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay also collect large statistics of Standard Model allowed two-neutrino double-$\beta$ ($2\nu\beta\beta$) decay events. These can be used to search for Beyond Standard Model (BSM) physics via $2\nu\beta\beta$ decay spectral distortions. $^{100}$Mo has a natural advantage due to its relatively short half-life, allowing higher $2\nu\beta\beta$ decay statistics at equal exposures compared to the other isotopes. We demonstrate the potential of the dual read-out bolometric technique exploiting a $^{100}$Mo exposure of 1.47 kg $\times$ y, acquired in the CUPID-Mo experiment at the Modane underground laboratory (France). We set limits on $0\nu\beta\beta$ decays with the emission of one or more Majorons, on $2\nu\beta\beta$ decay with Lorentz violation, and $2\nu\beta\beta$ decay with a sterile neutrino emission. In this analysis, we investigate the systematic uncertainty induced by modeling the $2\nu\beta\beta$ decay spectral shape parameterized through an improved model, an effect never considered before. This work motivates searches for BSM processes in the upcoming CUPID experiment, which will collect the largest amount of $2\nu\beta\beta$ decay events among the next-generation experiments.

nucl-ex↗

arXiv2024

BINGO innovative assembly for background reduction in bolometric $0\nu\beta\beta$ experiments

BINGO is a project aiming to set the grounds for large-scale bolometric neutrinoless double-beta-decay experiments capable of investigating the effective Majorana neutrino mass at a few meV level. It focuses on developing innovative technologies (a detector assembly, cryogenic photodetectors and active veto) to achieve a very low background index, of the order of $10^{-5}$ counts/(keV kg yr) in the region of interest. The BINGO demonstrator, called MINI-BINGO, is designed to investigate the promising double-beta-decay isotopes $^{100}$Mo and $^{130}$Te and it will be composed of Li$_2$MoO$_4$ and TeO$_2$ crystals coupled to bolometric light detectors and surrounded by a Bi$_4$Ge$_3$O$_{12}$-based veto. This will allow us to reject a significant background in bolometers caused by surface contamination from $\alpha$-active radionuclides by means of light yield selection and to mitigate other sources of background, such as surface contamination from $\beta$-active radionuclides, external $\gamma$ radioactivity, and pile-up due to random coincidence of background events. This paper describes an R\&D program towards the BINGO goals, particularly focusing on the development of an innovative assembly designed to reduce the passive materials within the line of sight of the detectors, which is expected to be a dominant source of background in next-generation bolometric experiments. We present the performance of two prototype modules -- housing four cubic (4.5-cm side) Li$_2$MoO$_4$ crystals in total -- operated in the Canfranc underground laboratory in Spain within a facility developed for the CROSS double-beta-decay experiment.

physics.ins-det↗

arXiv2024

Results from a Prototype TES Detector for the Ricochet Experiment

Coherent elastic neutrino-nucleus scattering (CE$ν$NS) offers valuable sensitivity to physics beyond the Standard Model. The Ricochet experiment will use cryogenic solid-state detectors to perform a precision measurement of the CE$ν$NS spectrum induced by the high neutrino flux from the Institut Laue-Langevin nuclear reactor. The experiment will employ an array of detectors, each with a mass of $\sim$30 g and a targeted energy threshold of 50 eV. Nine of these detectors (the "Q-Array") will be based on a novel Transition-Edge Sensor (TES) readout style, in which the TES devices are thermally coupled to the absorber using a gold wire bond. We present initial characterization of a Q-Array-style detector using a 1 gram silicon absorber, obtaining a baseline root-mean-square resolution of less than 40 eV.

physics.ins-det↗

arXiv2023

Measuring the CMB primordial B-modes with Bolometric Interferometry

The Q&U Bolometric Interferometer for Cosmology (QUBIC) is the first bolometric interferometer designed to measure the primordial B-mode polarization of the Cosmic Microwave Background (CMB). Bolometric interferometry is a novel technique that combines the sensitivity of bolometric detectors with the control of systematic effects that is typical of interferometry, both key features in the quest for the faint signal of the primordial B-modes. A unique feature is the so-called "spectral imaging", i.e., the ability to recover the sky signal in several sub-bands within the physical band during data analysis. This feature provides an in-band spectral resolution of Δν/ν \sim 0.04 that is unattainable by a traditional imager. This is a key tool for controlling the Galactic foregrounds contamination. In this paper, we describe the principles of bolometric interferometry, the current status of the QUBIC experiment and future prospects.

astro-ph.CO↗

arXiv2023

Test of $^{116}$CdWO$_4$ and Li$_2$MoO$_4$ scintillating bolometers in the CROSS underground facility with upgraded detector suspension

In preparation to the CROSS $2\beta$ decay experiment, we installed a new detector suspension with magnetic dumping inside a pulse-tube cryostat of a dedicated low-background facility at the LSC (Spain). The suspension was tested with two scintillating bolometers based on large-volume 116CdWO4 (CWO-enr) and Li2MoO4 (LMO) crystals. The former, a reference device, was used for testing new noise conditions and for comparing bolometric performance of an advanced Li2MoO4 crystal developed in the framework of the CLYMENE project, in view of next-generation double-beta decay experiments like CUPID. We cooled down detectors to 15 mK and achieved high performance for all tested devices. In particular both CWO-enr and LMO bolometers demonstrated the energy resolution of 6 keV FWHM for the 2.6 MeV gamma quanta, among the best for thermal detectors based on such compounds. The baseline noise resolution (FWHM) of the CWO-enr detector was improved by 2 keV, compared to the best previous measurement of this detector in the CROSS facility, while the noise of the Ge-based optical bolometer was improved by a factor 2, to 100 eV FWHM. Despite of the evident progress in the improving of noise conditions of the set-up, we see high-frequency harmonics of a pulse-tube induced noise, suggesting a noise pick-up by cabling. Another Ge light detector was assisted with the signal amplification exploiting the Neganov-Trofimov-Luke effect, which allowed to reach 20 eV FWHM noise resolution by applying 60 V electrode bias. Highly-efficient particle identification was achieved with both detectors, despite a low scintillation efficiency of the LMO material. The radiopurity level of the LMO crystal is rather high; only traces of 210Po and 226Ra were detected (0.1 mBq/kg each), while the 228Th activity is expected to be at least an order of magnitude lower, as well as a 40K activity is found to be < 6 mBq/kg.

physics.ins-det↗

arXiv2023

Measurement of the $2νββ$ decay rate and spectral shape of $^{100}$Mo from the CUPID-Mo experiment

Neutrinoless double beta decay ($0νββ$) is a yet unobserved nuclear process which would demonstrate Lepton Number violation, a clear evidence of beyond Standard Model physics. The process two neutrino double beta decay ($2νββ)$ is allowed by the Standard Model and has been measured in numerous experiments. In this letter, we report a measurement of $2νββ$ decay half-life of $^{100}$Mo to the ground state of $^{100}$Ru of $(7.07~\pm~0.02~\text{(stat.)}~\pm~0.11~\text{(syst.)})~\times~10^{18}$~yr by the CUPID-Mo experiment. With a relative precision of $\pm~1.6$ \% this is the most precise measurement to date of a $2νββ$ decay rate in $^{100}$Mo. In addition, we constrain higher-order corrections to the spectral shape which provides complementary nuclear structure information. We report a novel measurement of the shape factor $ξ_{3,1}=0.45~\pm 0.03~\text{(stat.)} \ \pm 0.05 \ \text{(syst.)}$, which is compared to theoretical predictions for different nuclear models. We also extract the first value for the effective axial vector coupling constant obtained from a spectral shape study of $2νββ$ decay.

nucl-ex↗

arXiv2023

Observation of a nuclear recoil peak at the 100 eV scale induced by neutron capture

Coherent elastic neutrino-nucleus scattering and low-mass Dark Matter detectors rely crucially on the understanding of their response to nuclear recoils. We report the first observation of a nuclear recoil peak at around 112 eV induced by neutron capture. The measurement was performed with a CaWO$_4$ cryogenic detector from the NUCLEUS experiment exposed to a $^{252}$Cf source placed in a compact moderator. The measured spectrum is found in agreement with simulations and the expected peak structure from the single-$γ$ de-excitation of $^{183}$W is identified with 3 $σ$ significance. This result demonstrates a new method for precise, in-situ, and non-intrusive calibration of low-threshold experiments.

nucl-ex↗

arXiv2023

First demonstration of 30 eVee ionization energy resolution with Ricochet germanium cryogenic bolometers

The future Ricochet experiment aims to search for new physics in the electroweak sector by measuring the Coherent Elastic Neutrino-Nucleus Scattering process from reactor antineutrinos with high precision down to the sub-100 eV nuclear recoil energy range. While the Ricochet collaboration is currently building the experimental setup at the reactor site, it is also finalizing the cryogenic detector arrays that will be integrated into the cryostat at the Institut Laue Langevin in early 2024. In this paper, we report on recent progress from the Ge cryogenic detector technology, called the CryoCube. More specifically, we present the first demonstration of a 30~eVee (electron equivalent) baseline ionization resolution (RMS) achieved with an early design of the detector assembly and its dedicated High Electron Mobility Transistor (HEMT) based front-end electronics. This represents an order of magnitude improvement over the best ionization resolutions obtained on similar heat-and-ionization germanium cryogenic detectors from the EDELWEISS and SuperCDMS dark matter experiments, and a factor of three improvement compared to the first fully-cryogenic HEMT-based preamplifier coupled to a CDMS-II germanium detector. Additionally, we discuss the implications of these results in the context of the future Ricochet experiment and its expected background mitigation performance.

astro-ph.IM↗

arXiv2023

Study of collision and $γ$-cascade times following neutron-capture processes in cryogenic detectors

The emission of $γ$-rays after a neutron capture in a cryogenic detector can generate mono-energetic nuclear recoils in the sub-keV regime, of direct interest for the calibration of Dark Matter and Coherent Elastic Neutrino Nucleus Scattering experiments. Here we show that accurate predictions of the nuclear recoil spectra induced by neutron captures require taking into account the interplay between the development in time of the de-excitation $γ$-cascade of the target nucleus and that of the associated atomic collisions in matter. We present detailed simulations coupling the FIFRELIN code for the description of the $γ$-cascades and the IRADINA code for the modelling of the fast atomic movements in matter. Nuclear recoil spectra are predicted, and made available to the community, for concrete cases of Al$_2$O$_3$, Si, Ge and CaWO$_4$ crystals exposed to a low intensity beam of thermal neutrons. We find that timing effects cause new calibration peaks to emerge in the recoil spectra and also impact the shape of the continuous recoil distribution. We discuss how they could give access to a rich physics program, spanning the accurate study of the response of cryogenic detectors in the sub-keV range, tests of solid state physics simulations and tests of nuclear models.

physics.ins-det↗