Modane Underground Laboratory Research Articles

Transition Edge Sensors with Sub-eV Resolution And Cryogenic Targets (TESSERACT) at the underground laboratory of Modane (LSM)

The future TESSERACT experiment will search for individual galactic DM particles below the proton mass through interactions with advanced, ultra-sensitive detectors. Currently TESSERACT is in a design phase aiming to produce fully defined detector technologies that will explore DM masses down to 10 MeV. It is designed to be sensitive to DM candidates interacting with the detector target material in producing both nuclear recoil DM (NRDM) and electron recoil (ERDM). To do so, multiple target materials will be used with varying detection strategies to ensure the capability to both actively reject the so-called low-energy excess and discriminate nuclear recoils against electron recoils. In addition to maximizing sensitivity to a variety of DM interactions, this provides an independent handle on instrumental backgrounds. Nowadays, the TESSERACT project encompasses two US-based technologies, namely HeRALD using superfluid helium as a target material, and SPICE using polar crystals (Al2O3 and SiO2) and scintillating crystals such as GaAs. In these proceedings, we discuss the recent proposal to host the future TESSERACT experiment at the Modane Underground Laboratory (LSM) and add a third French-based cryogenic semiconducting (Ge, Si) detector technology to the TESSERACT payload.

Cosmogenic background simulations for neutrinoless double beta decay with the DARWIN observatory at various underground sites

Xenon dual-phase time projections chambers (TPCs) have proven to be a successful technology in studying physical phenomena that require low-background conditions. With 40t\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$40\\,\ extrm{t}$$\\end{document} of liquid xenon (LXe) in the TPC baseline design, DARWIN will have a high sensitivity for the detection of particle dark matter, neutrinoless double beta decay (0νββ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0\\upnu \\upbeta \\upbeta $$\\end{document}), and axion-like particles (ALPs). Although cosmic muons are a source of background that cannot be entirely eliminated, they may be greatly diminished by placing the detector deep underground. In this study, we used Monte Carlo simulations to model the cosmogenic background expected for the DARWIN observatory at four underground laboratories: Laboratori Nazionali del Gran Sasso (LNGS), Sanford Underground Research Facility (SURF), Laboratoire Souterrain de Modane (LSM) and SNOLAB. We present here the results of simulations performed to determine the production rate of 137\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${}^{137}$$\\end{document}Xe, the most crucial isotope in the search for 0νββ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0\\upnu \\upbeta \\upbeta $$\\end{document} of 136\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${}^{136}$$\\end{document}Xe. Additionally, we explore the contribution that other muon-induced spallation products, such as other unstable xenon isotopes and tritium, may have on the cosmogenic background.

The background model of the CUPID-Mo 0nu beta beta experiment

CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a demonstrator for the next generation 0nu beta beta decay experiment, CUPID. It consisted of an array of 20 enriched Li_{2}^{100}MoO_4 bolometers and 20 Ge light detectors and has demonstrated that the technology of scintillating bolometers with particle identification capabilities is mature. Furthermore, CUPID-Mo can inform and validate the background prediction for CUPID. In this paper, we present a detailed model of the CUPID-Mo backgrounds. This model is able to describe well the features of the experimental data and enables studies of the 2nu beta beta decay and other processes with high precision. We also measure the radio-purity of the Li_{2}^{100}MoO_4 crystals which are found to be sufficient for the CUPID goals. Finally, we also obtain a background index in the region of interest of 3.7 ^{+0.9}_{-0.8} (stat)^{+1.5}_{-0.7} (syst) times ~10 ^{-3} counts/Delta E_{text {FWHM}}/text {mol}_{text {iso}}/text {year}, the lowest in a bolometric 0nu beta beta decay experiment.

The DAMIC-M experiment: Status and first results

The DAMIC-M (DArk Matter In CCDs at Modane) experiment employs thick, fully depleted silicon charged-coupled devices (CCDs) to search for dark matter particles with a target exposure of 1 kg-year. A novel skipper readout implemented in the CCDs provides single electron resolution through multiple non-destructive measurements of the individual pixel charge, pushing the detection threshold to the eV-scale. DAMIC-M will advance by several orders of magnitude the exploration of the dark matter particle hypothesis, in particular of candidates pertaining to the so-called “hidden sector.” A prototype, the Low Background Chamber (LBC), with 20g of low background Skipper CCDs, has been recently installed at Laboratoire Souterrain de Modane and is currently taking data. We will report the status of the DAMIC-M experiment and first results obtained with LBC commissioning data.

Sub-GeV dark matter searches with EDELWEISS: New results and prospects

The Edelweiss collaboration performs light Dark Matter (DM) particles searches with germanium bolometer collecting charge and phonon signals. Thanks to the Neganov-Trofimov-Luke (NTL) effect, a RMS resolution of 4.46 electron-hole pairs was obtained on a massive (200g) germanium detector instrumented with a NbSi Transition Edge Sensor (TES) operated underground at the Laboratoire Souterrain de Modane (LSM). This sensitivity made possible a search for WIMP using the Migdal effect down to 32 MeV/C^{2}2 and exclude cross-sections down to 10^{-29}−29 cm^22. It is the first measurement in cryogenic germanium with such thermal sensor, proving the high relevance of this technology. Furthermore, such TES have shown sensitivity to out-of-equilibrium phonons, paving the way for EDELWEISS new experience CRYOSEL. This is an important step in the development of Ge detectors with improved performance in the context of the EDELWEISS-SubGeV program.

New measurement of double- β decays of Mo100 to excited states of Ru100 with the CUPID-Mo experiment

The CUPID-Mo experiment, located at the Laboratoire Souterrain de Modane (France), was a demonstrator experiment for CUPID. It consisted of an array of 20Li2Mo100O4 (LMO) calorimeters, each equipped with a Ge light detector for particle identification. In this work, we present the result of a search for two-neutrino and neutrinoless double-β decays of Mo100 to the first 0+ and 2+ excited states of Ru100 using the full CUPID-Mo exposure (2.71kgyr of LMO). We measure the half-life of 2νββ decay to the 01+ state as T1/22ν→01+=(7.5±0.8(stat.)−0.3+0.4(syst.))×1020yr. The bolometric technique enables measurement of the electron energies as well as the γ rays from nuclear deexcitation and this allows us to set new limits on the two-neutrino decay to the 21+ state of T1/22ν→21+>4.4×1021yr(90% c.i.) and on the neutrinoless modes of T1/20ν→21+>2.1×1023yr(90% c.i.), T1/20ν→01+>1.2×1023yr(90% c.i.). Information on the electrons' spectral shape is obtained, which allows us to make the first comparison of the single and higher state dominance 2νββ decay models for the 01+ excited state of Ru100.8 MoreReceived 1 August 2022Accepted 2 December 2022DOI:https://doi.org/10.1103/PhysRevC.107.025503©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDouble beta decayNeutrinoless double beta decayNuclear structure & decaysPhysical SystemsMajorana neutrinosNeutrinosProperties90 ≤ A ≤ 149Nuclear Physics

Final results on the 0nu beta beta decay half-life limit of ^{100}Mo from the CUPID-Mo experiment

The CUPID-Mo experiment to search for 0nu beta beta decay in ^{100}Mo has been recently completed after about 1.5 years of operation at Laboratoire Souterrain de Modane (France). It served as a demonstrator for CUPID, a next generation 0nu beta beta decay experiment. CUPID-Mo was comprised of 20 enriched hbox {Li}_{{2}}^{100}hbox {MoO}_4 scintillating calorimeters, each with a mass of sim 0.2 kg, operated at sim 20 mK. We present here the final analysis with the full exposure of CUPID-Mo (^{100}Mo exposure of 1.47 hbox {kg} times hbox {year}) used to search for lepton number violation via 0nu beta beta decay. We report on various analysis improvements since the previous result on a subset of data, reprocessing all data with these new techniques. We observe zero events in the region of interest and set a new limit on the ^{100}Mo 0nu beta beta decay half-life of T_{1/2}^{0nu }> {1.8}times 10^{24} year (stat. + syst.) at 90% CI. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of left<m_{beta beta }right> <~{(0.28{-}0.49)} eV, dependent upon the nuclear matrix element utilized.

Search for sub-GeV dark matter via the Migdal effect with an EDELWEISS germanium detector with NbSi transition-edge sensors

The EDELWEISS collaboration reports on the search for Dark Matter (DM) particle interactions via Migdal effect with masses between $32$ MeV$\cdot$c$^{-2}$ to $2$ GeV$\cdot$c$^{-2}$ using a $200$ g cryogenic Ge detector sensitive to simultaneously heat and ionization signals and operated underground at the Laboratoire Souterrain de Modane in France. The phonon signal was read out using a Transition Edge Sensor made of a NbSi thin film. The detector was biased at $66$ V in order to benefit from the Neganov-Trofimov-Luke amplification and resulting in a resolution on the energy of electron recoils of $4.46$ eV$_{ee}$ (RMS) and an analysis threshold of $30$ eV$_{ee}$. The sensitivity is limited by a dominant background not associated to charge creation in the detector. The search constrains a new region of parameter space for cross-sections down to $10^{-29}$ cm$^2$ and masses between $32$ and $100$ MeV$\cdot$c$^{-2}$. The achieved low threshold with the NbSi sensor shows the relevance of its use for athermal-phonon sensitive devices for low-mass DM searches.

Using scientific-grade CCDs for the direct detection of dark matter with the DAMIC-M experiment

The DAMIC-M [1] project is devoted to the exploration of the hidden sector and the search for light dark matter particles using Charge-Coupled Devices (CCDs). It follows the DAMIC at SNOLAB [2] experiment which pioneered the detection of new particles through their interaction with the nucleus or the electrons of the bulk silicon of fully depleted CCDs. A kilogram-sized target mass will be installed at the Modane underground laboratory (LSM, France) which offers an excellent low background environment for rare-event search. DAMIC-M detectors demonstrate several technological advancements including the implementation of the skipper technique, and custom front-end control and read-out electronics. Skipper CCDs can perform multiple non-destructive measurements of the pixel charge which can lead to a read-out noise of a fraction of an electron. With a 15 μm × 15 μm pixel area, 675 μm thickness and the ability of 3D reconstruction using the diffusion of the particle track, the spatial resolution of our CCDs allows for the follow-up of radioactive chains, a powerful tool to discriminate genuine particle interaction from in situ radioactive decays. Together with an extremely careful fabrication procedure that controls the contaminant and the generation of bulk radioactive contamination by cosmic ray spallation, the single electron resolution will guarantee a detection energy threshold of only a few eVs, pushing the sensitivity of DAMIC-M by at least one order of magnitude better than previous experiments. I will present the current status of DAMIC-M describing our technological challenges and the solutions we have adopted. I will introduce our method to measure and mitigate the bulk radioactive contamination and discuss the ongoing assembly of a prototype detector, the Low Background Chamber (LBC), aiming at validating our design options.

Using scientific-grade CCDs for the direct detection of dark matter with the DAMIC-M experiment

The DAMIC-M (Dark matter in CCDs at Modane) experiment, successor of DAMIC at SNOLAB (Sudbury Neutrino Observatory laboratory), is devoted to the search for dark matter (DM) candidates interacting with the electrons or the nuclei of the bulk silicon of fully depleted Charge-Coupled Devices (CCDs). A kilogram-sized target mass will be installed at the Modane underground laboratory which offers an excellent low background environment for rare-event searches. The implementation of the Skipper readout allows for multiple non-destructive pixel charge measurements, reaching a readout noise of a fraction of an electron. This perfect performance in terms of charge resolution can be limited by the radioactive background and the noise introduced by the external electronics. Much effort is put into the protection of the silicon from contamination by cosmic ray spallation, careful choice of the materials to support and shield the CCDs, and development of a new acquisition system with fast and sensitive electronics for the control and readout of a CCD. All these advancements will push the detection threshold down to a few eVs, improving the sensitivity of DAMIC-M by at least one order of magnitude with respect to previous experiments. I will present the current status of DAMIC-M describing our technological challenges and the solutions we have adopted, and introduce the ongoing assembly of a prototype detector, the Low Background Chamber, aiming at validating our final design options and produce the first scientific results.

The search for Light Dark Matter with NEWS-G

The NEWS-G direct dark matter search experiment uses spherical proportional counters (SPC) with light noble gases to explore low WIMP masses. The first results obtained with an SPC prototype operated with Ne gas at the Laboratoire Souterrain de Modane (LSM) have already set competitive results for low-mass WIMPs. The forthcoming next phase of the experiment consists of a large 140 cm diameter SPC installed at SNOLAB with a new sensor design, with improved detector performance and data quality. Before its installation at SNOLAB, the detector was commissioned with pure methane gas at the LSM, with a temporary water shield, offering a hydrogen-rich target and reduced backgrounds. After giving an overview of the improvements of the detector, preliminary results of this campaign will be discussed, including UV laser and Ar-37 calibration data.

Investigation of β+β+, β+EC, EC/EC decay of 106Cd with the spectrometer TGV-2

The III phase of experiment TGV-2 to search for β+β+, β+EC, EC/EC decay of 106Cd was performed at the Modane underground laboratory (LSM, France, 4800 m w.e.). 16 foils (∼23.2 g) of enriched 106Cd were measured using the 32-detector low background HPGe spectrometer TGV-2 during 42500 h. New limit on 2νEC/EC decay of 106Cd to the ground 0+ state of 106Pd - T1/2 > 7.2 × 1020 y at 90% C.L was obtained. The limits on 2νβ+β+, 2νβ+EC decay of 106Cd, and 2νECEC decay of 106Cd to excited states of 106Pd were significantly improved in comparison with previous phase II of the TGV-2 experiment.

EXPERIMENTS AT MODANE UNDERGROUND LABORATORY OR THE SWAN SONG OF RADIOCARBON ß-COUNTING BY GAS PROPORTIONAL COUNTER

ABSTRACTIn 1991, a 14C ß-counting installation with four proportional CO2 gas counters was tested at the Modane underground laboratory, 1700 m below the summit of Pointe du Fréjus, reducing the muon flux to 4 muons per square meter and per day. With cosmic radiation attenuated by a factor of 2.106, the background level of the counters was reduced by 65 to 85% while its variability was reduced by a factor of 30–80 depending on the type of counter. The dating limit of these counters extends to well beyond 60,000 years.

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 bolometric 0νββ experiment. It consists of a 4.2kg 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 (^{100}Mo exposure of 1.17 kg×yr for 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}>1.5×10^{24} yr at 90% C.I. The limit corresponds to an effective Majorana neutrino mass ⟨m_{ββ}⟩<(0.31-0.54) eV, dependent on the nuclear matrix element in the light Majorana neutrino exchange interpretation.

Copper electroplating for background suppression in the NEWS-G experiment

New Experiments with Spheres-Gas (NEWS-G) is a dark matter direct detection experiment that will operate at SNOLAB (Canada). Similar to other rare-event searches, the materials used in the detector construction are subject to stringent radiopurity requirements. The detector features a 140-cm diameter proportional counter comprising two hemispheres made from commercially sourced 99.99% pure copper. Such copper is widely used in rare-event searches because it is readily available, there are no long-lived Cu radioisotopes, and levels of non-Cu radiocontaminants are generally low. However, measurements performed with a dedicated 210Po alpha counting method using an XIA detector confirmed a problematic concentration of 210Pb in bulk of the copper. To shield the proportional counter’s active volume, a low-background electroforming method was adapted to the hemispherical shape to grow a 500-µm thick layer of ultra-radiopure copper to the detector’s inner surface. In this paper the process is described, which was prototyped at Pacific Northwest National Laboratory (PNNL), USA, and then conducted at full scale in the Laboratoire Souterrain de Modane in France. The radiopurity of the electroplated copper was assessed through Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Measurements of samples from the first (second) hemisphere give 68% confidence upper limits of <0.58µBq/kg (<0.24µBq/kg) and <0.26µBq/kg (<0.11µBq/kg) on the 232Th and 238U contamination levels, respectively. These results are comparable to previously reported measurements of electroformed copper produced for other rare-event searches, which were also found to have low concentration of 210Pb consistent with the background goals of the NEWS-G experiment.

Searching for the β+EC and EC/EC Decays of 74Se

Double beta decay (β+EC, EC/EC) of 74Se was investigated at the Modane underground laboratory (LSM, France; 4800 m of water equivalent) using the OBELIX ultralow-background HPGe detector with a sensitive volume of 600 cm3 and a sample of natural selenium with a mass of 1.6 kg containing ~0.89% (~14.24 g) of 74Se. The new experimental limits for β+EC and EC/EC decays of 74Se to ground 0+ and excited $$2_{1}^{ + },$$ 596 keV, and $$2_{2}^{ + },$$ 1204 keV states of 74Ge, were obtained from experimental data accumulated over 135 days.

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

We report the measurement of the two-neutrino double-beta (2nu beta beta ) decay of ^{100}Mo to the ground state of ^{100}Ru using lithium molybdate (hbox {Li}_2^{;;100}hbox {MoO}_4) 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 (France). From a total exposure of 42.235 kgtimes day, the half-life of ^{100}Mo is determined to be T_{1/2}^{2nu }=[7.12^{+0.18}_{-0.14},mathrm {(stat.)}pm 0.10,mathrm {(syst.)}]times 10^{18} years. This is the most accurate determination of the 2nu beta beta half-life of ^{100}Mo to date.

Natural radionuclides as background sources in the Modane underground laboratory

The Modane underground laboratory (LSM) is the deepest operating underground laboratory in Europe. It is located under the Fréjus peak in Savoie Alps in France, with average overburden of 4800 m w. e. (water equivalent), providing low-background environment for experiments in nuclear and particle physics, astrophysics and environmental physics. It is crucial to understand individual sources of background such as residual cosmic-ray flux of high-energy muons, muon-induced neutrons and contributions from radionuclides present in the environment. The identified dominant sources of background are radioactive contamination of construction materials of detectors and laboratory walls, radon contamination of the laboratory air, and neutrons produced in the laboratory. The largest neutron contribution has been identified from (α, n) reactions in low Z materials (10−7-10−4 n s−1 Bq−1) and from spontaneous fission of 238U (1.1× 10−6 n s−1 Bq−1).

CUPID: CUORE Upgrade with Particle IDentification

CUPID is a next generation Double Beta Decay experiment based on scintillating bolometers. The already developed CUORE infrastructure will become the site in which the new detector will be installed. The technology, successfully tested in Laboratory Nazionali del Gran Sasso by CUPID-0 and in Laboratoire Souterrain de Modane by CUPID-Mo, will provide the rejection capability that allows to reduce the background by two orders of magnitude with respect to CUORE one. This result will be achieved using enriched Li2MoO4 scintillating bolometers for the study of the 100Mo isotope. The estimated discover sensitivity of CUPID for the effective neutrino Majorana mass is of the order of 20 meV .

Dark Matter in CCDs at Modane (DAMIC-M): a silicon detector apparatus searching for low-energy physics processes

Dark Matter In CCDs (DAMIC) is a silicon detector apparatus used primarily for searching for low-mass dark matter using the silicon bulk of Charge-Coupled Devices (CCDs) as targets. The silicon target within each CCD is 675 μm thick and its top surface is divided into over 16 million 15 μm × 15 μm pixels. The DAMIC collaboration has installed a number of these CCDs at SNOLAB. As of 2019, DAMIC at SNOLAB has reached operational conditions with leakage current less than 8.2 ×10-22 A cm-2 and a readout noise of 1.6 e, achieved with 5 CCDs. A new DAMIC apparatus will be installed at Laboratoire Souterrain de Modane in a few years. The DAMIC at Modane (DAMIC-M) collaboration will be using an improved version of CCDs designed by Lawrence Berkeley National Laboratory with skipper amplifiers that use non-destructive readout with multiple-sampling, enabling the CCDs to achieve a readout noise of 0.068 e. The low readout noise, in conjunction with low leakage current of these skipper CCDs, will allow DAMIC-M to observe physics processes with collisions energies as low as 1 eV. The DAMIC-M experiment will consist of an array of 50 large-area skipper CCDs with more than 36 million pixels in each CCD. The following proceeding will introduce the DAMIC apparatus at SNOLAB and its results and as well as the capabilities and the status of the new DAMIC-M experiment.