arXiv subjects

E. Olivieri

Publications and source records attributed to E. Olivieri.

At least 55 records · Page 3Linked to original sources

arXiv2021

QUBIC V: Cryogenic system design and performance

Current experiments aimed at measuring the polarization of the Cosmic Microwave Background (CMB) use cryogenic detector arrays and cold optical systems to boost the mapping speed of the sky survey. For these reasons, large volume cryogenic systems, with large optical windows, working continuously for years, are needed. Here we report on the cryogenic system of the QUBIC (Q and U Bolometric Interferometer for Cosmology) experiment: we describe its design, fabrication, experimental optimization and validation in the Technological Demonstrator configuration. The QUBIC cryogenic system is based on a large volume cryostat, using two pulse-tube refrigerators to cool at ~3K a large (~1 m^3) volume, heavy (~165kg) instrument, including the cryogenic polarization modulator, the corrugated feedhorns array, and the lower temperature stages; a 4He evaporator cooling at ~1K the interferometer beam combiner; a 3He evaporator cooling at ~0.3K the focal-plane detector arrays. The cryogenic system has been tested and validated for more than 6 months of continuous operation. The detector arrays have reached a stable operating temperature of 0.33K, while the polarization modulator has been operated from a ~10K base temperature. The system has been tilted to cover the boresight elevation range 20 deg -90 deg without significant temperature variations. The instrument is now ready for deployment to the high Argentinean Andes.

astro-ph.IM↗

arXiv2021

QUBIC VIII: Optical design and performance

The Q and U Bolometric Interferometer for Cosmology (QUBIC) is a ground-based experiment that aims to detect B-mode polarisation anisotropies in the CMB at angular scales around the l=100 recombination peak. Systematic errors make ground-based observations of B modes at millimetre wavelengths very challenging and QUBIC mitigates these problems in a somewhat complementary way to other existing or planned experiments using the novel technique of bolometric interferometry. This technique takes advantage of the sensitivity of an imager and the systematic error control of an interferometer. A cold reflective optical combiner superimposes there-emitted beams from 400 aperture feedhorns on two focal planes. A shielding system composedof a fixed groundshield, and a forebaffle that moves with the instrument, limits the impact of local contaminants. The modelling, design, manufacturing and preliminary measurements of the optical components are described in this paper.

astro-ph.IM↗

arXiv2021

Phonon-mediated crystal detectors with metallic film coating capable of rejecting $α$ and $β$ events induced by surface radioactivity

Phonon-mediated particle detectors based on single crystals and operated at millikelvin temperatures are used in rare-event experiments for neutrino physics and dark-matter searches. In general, these devices are not sensitive to the particle impact point, especially if the detection is mediated by thermal phonons. In this Letter, we demonstrate that excellent discrimination between interior and surface $β$ and $α$ events can be achieved by coating a crystal face with a thin metallic film, either continuous or in the form of a grid. The coating affects the phonon energy down-conversion cascade that follows the particle interaction, leading to a modified signal shape for close-to-film events. An efficient identification of surface events was demonstrated with detectors based on a rectangular $20 \times 20 \times 10$ mm$^3$ Li$_2$MoO$_4$ crystal coated with a Pd normal-metal film (10~nm thick) and with Al-Pd superconductive bi-layers (100~nm-10~nm thick) on a $20 \times 20$ mm$^2$ face. Discrimination capabilities were tested with $^{238}$U sources emitting both $α$ and $β$ particles. Surface events are identified for energy depositions down to millimeter-scale depths from the coated surface. With this technology, a substantial improvement of the background figure can be achieved in experiments searching for neutrinoless double-beta decay.

physics.ins-det↗

arXiv2021

New Limit for Neutrinoless Double-Beta Decay of $^{100}$Mo from the CUPID-Mo Experiment

The CUPID-Mo experiment at the Laboratoire Souterrain de Modane (France) is a demonstrator for CUPID, the next-generation ton-scale cryogenic $0νββ$ experiment. It consists of a 4.2 kg array of 20 enriched Li$_{2}$$^{100}$MoO$_4$ scintillating bolometers to search for the lepton number violating process of $0νββ$ decay in $^{100}$Mo. With more than one year of operation (2.16 kg$\times$yr of physics data), no event in the region of interest and hence no evidence for $0νββ$ is observed. We report a new limit on the half-life of $0νββ$ decay in $^{100}$Mo of $T_{1/2} > 1.5 \times 10^{24}\,$yr at 90 % C.I. The limit corresponds to an effective Majorana neutrino mass $\langle m_{ββ} \rangle$ $<$ (0.31--0.54)$\,$eV, dependent on the nuclear matrix element in the light Majorana neutrino exchange interpretation.

nucl-ex↗

arXiv2021

Pulse Shape Discrimination in CUPID-Mo using Principal Component Analysis

CUPID-Mo is a cryogenic detector array designed to search for neutrinoless double-beta decay ($0νββ$) of $^{100}$Mo. It uses 20 scintillating $^{100}$Mo-enriched Li$_2$MoO$_4$ bolometers instrumented with Ge light detectors to perform active suppression of $α$ backgrounds, drastically reducing the expected background in the $0νββ$ signal region. As a result, pileup events and small detector instabilities that mimic normal signals become non-negligible potential backgrounds. These types of events can in principle be eliminated based on their signal shapes, which are different from those of regular bolometric pulses. We show that a purely data-driven principal component analysis based approach is able to filter out these anomalous events, without the aid of detector response simulations.

physics.data-an↗

arXiv2020

QUBIC VI: cryogenic half wave plate rotator, design and performances

Inflation Gravity Waves B-Modes polarization detection is the ultimate goal of modern large angular scale cosmic microwave background (CMB) experiments around the world. A big effort is undergoing with the deployment of many ground-based, balloon-borne and satellite experiments using different methods to separate this faint polarized component from the incoming radiation. One of the largely used technique is the Stokes Polarimetry that uses a rotating half-wave plate (HWP) and a linear polarizer to separate and modulate the polarization components with low residual cross-polarization. This paper describes the QUBIC Stokes Polarimeter highlighting its design features and its performances. A common systematic with these devices is the generation of large spurious signals synchronous with the rotation and proportional to the emissivity of the optical elements. A key feature of the QUBIC Stokes Polarimeter is to operate at cryogenic temperature in order to minimize this unwanted component. Moving efficiently this large optical element at low temperature constitutes a big engineering challenge in order to reduce friction power dissipation. Big attention has been given during the designing phase to minimize the differential thermal contractions between parts. The rotation is driven by a stepper motor placed outside the cryostat to avoid thermal load dissipation at cryogenic temperature. The tests and the results presented in this work show that the QUBIC polarimeter can easily achieve a precision below 0.1° in positioning simply using the stepper motor precision and the optical absolute encoder. The rotation induces only few mK of extra power load on the second cryogenic stage (~ 8 K).

astro-ph.IM↗

arXiv2020

The CROSS Experiment: Rejecting Surface Events by PSD Induced by Superconducting Films

Neutrinoless double beta ($0νββ$) decay is a hypothetical rare nuclear transition ($T_{1/2}>10^{26}$ y). Its observation would provide an important insight about the nature of neutrinos (Dirac or Majorana particle) demonstrating that the lepton number is not conserved. This decay can be investigated with bolometers embedding the double beta decay isotope ($^{76}$Ge, $^{82}$Se, $^{100}$Mo, $^{116}$Cd, $^{130}$Te...), which perform as low temperature calorimeters (10 mK) detecting particle interactions via a small temperature rise read out by a dedicated thermometer. CROSS (Cryogenic Rare-event Observatory with Surface Sensitivity) aims at the development of bolometric detectors (Li$_{2}$MoO$_{4}$ and TeO$_{2}$) capable of discriminating surface $α$ and $β$ interactions by exploiting superconducting properties of Al film deposited on the crystal surface. We report in this paper the results of tests on prototypes performed at CSNSM (Orsay, France) that showed the capability of a-few-$μ$m-thick superconducting Al film deposited on crystal surface to discriminate surface $α$ from bulk events, thus providing the detector with the required surface sensitivity capability. The CROSS technology would further improve the background suppression and simplify the detector construction with a view to future competitive double beta decay searches.

physics.ins-det↗

arXiv2020

QUBIC: the Q & U Bolometric Interferometer for Cosmology

The Q & U Bolometric Interferometer for Cosmology, QUBIC, is an innovative experiment designed to measure the polarization of the Cosmic Microwave Background and in particular the signature left therein by the inflationary expansion of the Universe. The expected signal is extremely faint, thus extreme sensitivity and systematic control are necessary in order to attempt this measurement. QUBIC addresses these requirements using an innovative approach combining the sensitivity of Transition Edge Sensor cryogenic bolometers, with the deep control of systematics characteristic of interferometers. This makes QUBIC unique with respect to others classical imagers experiments devoted to the CMB polarization. In this contribution we report a description of the QUBIC instrument including recent achievements and the demonstration of the bolometric interferometry performed in lab. QUBIC will be deployed at the observation site in Alto Chorrillos, in Argentina at the end of 2019.

astro-ph.IM↗

arXiv2019

Precise measurement of $2νββ$ decay of $^{100}$Mo with the CUPID-Mo detection technology

We report the measurement of the two-neutrino double-beta ($2νββ$) decay of $^{100}$Mo to the ground state of $^{100}$Ru using lithium molybdate (\crystal) scintillating bolometers. The detectors were developed for the CUPID-Mo program and operated at the EDELWEISS-III low background facility in the Modane underground laboratory. From a total exposure of $42.235$ kg$\times$d, the half-life of $^{100}$Mo is determined to be $T_{1/2}^{2ν}=[7.12^{+0.18}_{-0.14}\,\mathrm{(stat.)}\pm0.10\,\mathrm{(syst.)}]\times10^{18}$ years. This is the most accurate determination of the $2νββ$ half-life of $^{100}$Mo to date. We also confirm, with the statistical significance of $>3σ$, that the single-state dominance model of the $2νββ$ decay of $^{100}$Mo is favored over the high-state dominance model.

nucl-ex↗

arXiv2019

QUBIC: using NbSi TESs with a bolometric interferometer to characterize the polarisation of the CMB

QUBIC (Q \& U Bolometric Interferometer for Cosmology) is an international ground-based experiment dedicated in the measurement of the polarized fluctuations of the Cosmic Microwave Background (CMB). It is based on bolometric interferometry, an original detection technique which combine the immunity to systematic effects of an interferometer with the sensitivity of low temperature incoherent detectors. QUBIC will be deployed in Argentina, at the Alto Chorrillos mountain site near San Antonio de los Cobres, in the Salta province. The QUBIC detection chain consists in 2048 NbSi Transition Edge Sensors (TESs) cooled to 350mK.The voltage-biased TESs are read out with Time Domain Multiplexing based on Superconducting QUantum Interference Devices (SQUIDs) at 1 K and a novel SiGe Application-Specific Integrated Circuit (ASIC) at 60 K allowing to reach an unprecedented multiplexing (MUX) factor equal to 128. The QUBIC experiment is currently being characterized in the lab with a reduced number of detectors before upgrading to the full instrument. I will present the last results of this characterization phase with a focus on the detectors and readout system.

astro-ph.IM↗

arXiv2019

First data from the CUPID-Mo neutrinoless double beta decay experiment

The CUPID-Mo experiment is searching for neutrinoless double beta decay in $^{100}$Mo, evaluating the technology of cryogenic scintillating Li$_{2}^{100}$MoO$_4$ detectors for CUPID (CUORE Upgrade with Particle ID). CUPID-Mo detectors feature background suppression using a dual-readout scheme with Li$_{2}$MoO$_4$ crystals complemented by Ge bolometers for light detection. The detection of both heat and scintillation light signals allows the efficient discrimination of $α$ from $γ$&$β$ events. In this proceedings, we discuss results from the first 2 months of data taking in spring 2019. In addition to an excellent bolometric performance of 6.7$\,$keV (FWHM) at 2615$\,$keV and an $α$ separation of better than 99.9\% for all detectors, we report on bulk radiopurity for Th and U. Finally, we interpret the accumulated physics data in terms of a limit of $T_{1/2}^{0ν}\,> 3\times10^{23}\,$yr for $^{100}$Mo and discuss the sensitivity of CUPID-Mo until the expected end of physics data taking in early 2020.

hep-ex↗

arXiv2019

The $0\nu2β$-decay CROSS experiment: preliminary results and prospects

Neutrinoless double-beta decay is a key process in particle physics. Its experimental investigation is the only viable method that can establish the Majorana nature of neutrinos, providing at the same time a sensitive inclusive test of lepton number violation. CROSS (Cryogenic Rare-event Observatory with Surface Sensitivity) aims at developing and testing a new bolometric technology to be applied to future large-scale experiments searching for neutrinoless double-beta decay of the promising nuclei $^{100}$Mo and $^{130}$Te. The limiting factor in large-scale bolometric searches for this rare process is the background induced by surface radioactive contamination, as shown by the results of the CUORE experiment. The basic concept of CROSS consists of rejecting this challenging background component by pulse-shape discrimination, assisted by a proper coating of the faces of the crystal containing the isotope of interest and serving as energy absorber of the bolometric detector. In this paper, we demonstrate that ultra-pure superconductive Al films deposited on the crystal surfaces act successfully as pulse-shape modifiers, both with fast and slow phonon sensors. Rejection factors higher than 99.9% of $α$ surface radioactivity have been demonstrated in a series of prototypes based on crystals of Li$_2$MoO$_4$ and TeO$_2$. We have also shown that point-like energy depositions can be identified up to a distance of $\sim 1$ mm from the coated surface. The present program envisions an intermediate experiment to be installed underground in the Canfranc laboratory (Spain) in a CROSS-dedicated facility. This experiment, comprising $\sim 3\times 10^{25}$ nuclei of $^{100}$Mo, will be a general test of the CROSS technology as well as a worldwide competitive search for neutrinoless double-beta decay, with sensitivity to the effective Majorana mass down to 70 meV in the most favorable conditions.

nucl-ex↗

arXiv2019

The CUPID-Mo experiment for neutrinoless double-beta decay: performance and prospects

CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay ($0νββ$) of $^{100}$Mo. In this article, we detail the CUPID-Mo detector concept, assembly, installation in the underground laboratory in Modane in 2018, and provide results from the first datasets. The demonstrator consists of an array of 20 scintillating bolometers comprised of $^{100}$Mo-enriched 0.2 kg Li$_2$MoO$_4$ crystals. The detectors are complemented by 20 thin cryogenic Ge bolometers acting as light detectors to distinguish $α$ from $γ$/$β$ events by the detection of both heat and scintillation light signals. We observe good detector uniformity, facilitating the operation of a large detector array as well as excellent energy resolution of 5.3 keV (6.5 keV) FWHM at 2615 keV, in calibration (physics) data. Based on the observed energy resolutions and light yields a separation of $α$ particles at much better than 99.9\% with equally high acceptance for $γ$/$β$ events is expected for events in the region of interest for $^{100}$Mo $0νββ$. We present limits on the crystals' radiopurity ($\leq$3 $μ$Bq/kg of $^{226}$Ra and $\leq$2 $μ$Bq/kg of $^{232}$Th). Based on these initial results we also discuss a sensitivity study for the science reach of the CUPID-Mo experiment, in particular, the ability to set the most stringent half-life limit on the $^{100}$Mo $0νββ$ decay after half a year of livetime. The achieved results show that CUPID-Mo is a successful demonstrator of the technology - developed in the framework of the LUMINEU project - selected for the CUPID experiment, a proposed follow-up of CUORE, the currently running first tonne-scale cryogenic $0νββ$ experiment.

physics.ins-det↗

arXiv2019

Charge-to-heat transducers exploiting the Neganov-Trofimov-Luke effect for light detection in rare-event searches

In this work we present how to fabricate large-area (15 cm2), ultra-low threshold germanium bolometric photo-detectors and how to operate them to detect few (optical) photons. These detectors work at temperatures as low as few tens of mK and exploit the Neganov-Trofimov-Luke (NTL) effect. They are operated as charge-to-heat transducers: the heat signal is linearly increased by simply changing a voltage bias applied to special metal electrodes, fabricated onto the germanium absorber, and read by a (NTD-Ge) thermal sensor. We fabricated a batch of five prototypes and ran them in different facilities with dilution refrigerators. We carefully studied how impinging spurious infrared radiation impacts the detector performances, by shining infrared photons via optical-fiber-guided LED signals, in a controlled manner, into the bolometers. We hence demonstrated how the radiation-tightness of the test environment tremendously enhances the detector performances, allowing to set electrode voltage bias up to 90 volts without any leakage current and signal-to-noise gain as large as a factor 12 (for visible photons). As consequence, for the first time we could operate large-area NTD-Ge-sensor-equipped NTL bolometric photo-detectors capable to reach sub 10-eV baseline noise (RMS). Such detectors open new frontiers for rare-event search experiments based on low light yield Ge-NTD equipped scintillating bolometers, such the CUPID neutrinoless double-beta decay experiment.

physics.ins-det↗

arXiv2019

Searching for low-mass dark matter particles with a massive Ge bolometer operated above-ground

The EDELWEISS collaboration has performed a search for dark matter particles with masses below the GeV-scale with a 33.4-g germanium cryogenic detector operated in a surface lab. The energy deposits were measured using a neutron-transmutation-doped Ge thermal sensor with a 17.7~eV (RMS) baseline heat energy resolution leading to a 60~eV analysis energy threshold. Despite a moderate lead shielding and the high-background environment, the first sub-GeV spin-independent dark matter limit based on a germanium target has been achieved. The experiment provides the most stringent, nuclear recoil based, above-ground limit on spin-independent interactions above 600~MeV/c$^{2}$. The experiment also provides the most stringent limits on spin-dependent interactions with protons and neutrons below 1.3~GeV/c$^{2}$. Furthermore, the dark matter search results were studied in the context of Strongly Interacting Massive Particles, taking into account Earth-shielding effects, for which new regions of the available parameter space have been excluded. Finally, the dark matter search has also been extended to interactions via the Migdal effect, resulting for the first time in the exclusion of particles with masses between 45 and 150~MeV/c$^{2}$ with spin-independent cross sections ranging from $10^{-29}$ to $10^{-26}$~cm$^2$.

astro-ph.GA↗

arXiv2018

Thermal architecture for the QUBIC cryogenic receiver

QUBIC, the QU Bolometric Interferometer for Cosmology, is a novel forthcoming instrument to measure the B-mode polarization anisotropy of the Cosmic Microwave Background. The detection of the B-mode signal will be extremely challenging; QUBIC has been designed to address this with a novel approach, namely bolometric interferometry. The receiver cryostat is exceptionally large and cools complex optical and detector stages to 40 K, 4 K, 1 K and 350 mK using two pulse tube coolers, a novel 4He sorption cooler and a double-stage 3He/4He sorption cooler. We discuss the thermal and mechanical design of the cryostat, modelling and thermal analysis, and laboratory cryogenic testing.

astro-ph.IM↗

arXiv2018

Searches for electron interactions induced by new physics in the EDELWEISS-III germanium bolometers

We make use of the EDELWEISS-III array of germanium bolometers to search for electron interactions at the keV scale induced by phenomena beyond the Standard Model. A 90% C.L. lower limit is set on the electron lifetime decaying to invisibles, $τ> 1.2\times 10^{24}$ years. We investigate the emission of axions or axionlike particles (ALPs) by the Sun, constraining the coupling parameters $g_{ae}<1.1\times 10^{-11}$ and $g_{ae}\times g_{aN}^{\rm eff} < 3.5\times 10^{-17}$ at 90% C.L. in the massless limit. We also directly search for the absorption of bosonic dark matter particles that would constitute our local galactic halo. Limits are placed on the couplings of ALPs or hidden photon dark matter in the mass range $0.8 - 500$ keV/c$^2$. Prospects for searching for dark matter particles with masses down to 150 eV/c$^2$ using improved detectors are presented.

hep-ex↗

arXiv2018

Vibration decoupling system for massive bolometers in dry cryostats

Pulse-tube based dilution refrigerators are massively employed in low temperature physics. They allow to reduce the running costs and to be operated with unprecedented easiness. However, the main drawback of this technology is the mechanical vibrations induced by the pulse-tube cryocooler. These perturbations can cause extra-noises drastically affecting the detector performance. In this paper, we propose a solution to mitigate the impact of these vibrations by mounting the detectors in an elastic-pendulum based suspended tower. Based on vibration modeling and experimental tests, we show that the vibration levels are attenuated by up to two orders of magnitude at most frequencies, especially above $\sim20$ Hz, for both vertical and radial directions. Thanks to this passive isolation solution, vibration levels, both along vertical and radial directions, below 1 $μ\textrm{g/}\sqrt{\text{Hz}}$ in the frequency range [1-1000] Hz are obtained. This provides a convenient environment to test the ultimate performance of low temperature detectors. As a result, we report an improvement by one to two orders of magnitude on the noise levels of massive cryogenic bolometers, leading to thermal energy resolutions improved by a factor 5 to 40. Finally, we conclude that the energy resolution of our cryogenic bolometers are no longer limited from any residual vibrations, hence allowing the perspective of further improving our bolometer performance in the context of low-mass dark matter searches and neutrino physics applications.

physics.ins-det↗