Publications

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• Measurement of low-energy Compton and neutron scattering in Si CCDs for dark matter searches

  Radomir Smida for the DAMIC-M Collaboration

  SciPost Phys. Proc. 12, 015 (2023) · published 3 July 2023 | Toggle abstract · pdf

  For optimal sensitivity to low-mass dark matter candidates experiments like DAMIC-M employ skipper charged-coupled devices (CCDs) with detection threshold of just a few ionization charges. Ionization signals from small-angle Compton scatters of environmental $\gamma$-rays, an important component of the background in dark matter searches, must thus be characterized down to $O$(10 eV) energy. Using a $^{241}$Am $\gamma$-ray source, we report a precise measurement of scattering on Si atomic shell electrons in a skipper CCD with single-electron resolution. Notable differences are observed between data and theoretical expectations in the L-shell energy region ($<$150 eV). We also present preliminary data from a skipper CCD exposed to low-energy neutrons ($<$24 keV) from a $^{124}$Sb$^9$Be photoneutron source, demonstrating a measurement of the nuclear recoil ionization efficiency in Si down to few ionization charges.

• The DAMIC-M experiment: Status and first results

  Isaac J. Arnquist, Nicolas Avalos, Philippe Bailly, David Baxter, Xavier Bertou, Mircea Bogdan, Christian Bourgeois, J. Brandt, Arnaud Cadiou, Nuria Castelló-Mor, Alvaro E. Chavarria, Marcel Conde, Nicholas J. Corso, J. C. Gutiérrez, Julian Cuevas-Zepeda, Ali Dastgheibi-Fard, Claudia De Dominicis, Olivier Deligny, R. Desani, Marc Dhellot, Jean-Jacques Dormard, Jordi Duarte-Campderros, E. Estrada, D. Florin, N. Gadola, R. Gaïor, J. González Sánchez, Todd W. Hossbach, Michael Huehn, Latifa Khalil, Ben Kilminster, Agustin Lantero-Barreda, Ian Lawson, Hervé Lebbolo, Steven Lee, Pascal Leray, Antoine Letessier-Selvon, Pia Loaiza, Amparo Lopez-Virto, David Martin, Ariel Matalon, Kellie McGuire, T. Milleto, Pitam Mitra, David M. Martin, S. Munagavalasa, Danielle Norcini, Cory T. Overman, Giorgos Papadopoulos, S. Paul, David Peterson, Alexander Piers, Olivier Pochon, Paolo Privitera, Karthik Ramanathan, Denis Reynet, Peter Robmann, Ryan Roehnelt, Mariangela Settimo, Radomir Smida, Ben Stillwell, Ryan Thomas, Michelangelo Traina, Philippe Vallerand, Tim Van Wechel, Ivan Vila, Rocio V. Cortabitarte, Achim Vollhardt, Guillaume Warot, D. Wolf, Rachana Yajur, J-P. Zopounidis

  SciPost Phys. Proc. 12, 014 (2023) · published 3 July 2023 | Toggle abstract · pdf

  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.

  2 citations

• Latest observations on the low energy excess in CRESST-III

  G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. von Feilitzsch, N. Ferreiro Iachellini, S. Fichtinger, D. Fuchs, A. Fuss, A. Garai, V. M. Ghete, S. Gerster, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff, M. Ješkovský, J. Jochum, M. Kaznacheeva, A. Kinast, H. Kluck, H. Kraus, A. Langenkämper, M. Mancuso, L. Marini, L. Meyer, V. Mokina, A. Nilima, M. Olmi, T. Ortmann, C. Pagliarone, L. Pattavina, F. Petricca, W. Potzel, P. Povinec, F. Pröbst, F. Pucci, F. Reindl, J. Rothe, K. Schäffner, J. Schieck, D. Schmiedmayer, S. Schönert, C. Schwertner, M. Stahlberg, L. Stodolsky, C. Strandhagen, R. Strauss, I. Usherov, F. Wagner, M. Willers, V. Zema

  SciPost Phys. Proc. 12, 013 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The CRESST experiment observes an unexplained excess of events at low energies. In the current CRESST-III data-taking campaign we are operating detector modules with different designs to narrow down the possible explanations. In this work, we show first observations of the ongoing measurement, focusing on the comparison of time, energy and temperature dependence of the excess in several detectors. These exclude dark matter, radioactive backgrounds and intrinsic sources related to the crystal bulk as a major contribution.

  4 citations

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

  Hugues Lattaud on behalf of the EDELWEISS collaboration

  SciPost Phys. Proc. 12, 012 (2023) · published 3 July 2023 | Toggle abstract · pdf

  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$^{2}$ and exclude cross-sections down to 10$^{-29}$ cm$^2$. 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.

  1 citation

• The low-energy spectrum in DAMIC at SNOLAB

  Alvaro E. Chavarria

  SciPost Phys. Proc. 12, 011 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The DAMIC experiment employs large-area, thick charge-coupled devices (CCDs) to search for the interactions of low-mass dark matter particles in the galactic halo with silicon atoms in the CCD target. From 2017 to 2019, DAMIC collected data with a seven-CCD array (40-gram target) installed in the SNOLAB underground laboratory. We report dark-matter search results, including a conspicuous excess of events above the background model below 200$V_{ee}$, whose origin remains unknown. We present details of the published spectral analysis, and update on the deployment of skipper CCDs to perform a more precise measurement by early 2023.

• Energy loss due to defect creation in solid state detectors

  Matti Heikinheimo, Sebastian Sassi, Kimmo Tuominen, Kai Nordlund, Nader Mirabolfathi

  SciPost Phys. Proc. 12, 010 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The threshold displacement energy in solid state detector materials varies from several eV to $\lesssim$ 100 eV. If a stable or long lived defect is created as a result of a nuclear recoil event, some part of the recoil energy is stored in the deformed lattice and is therefore not observable in a phonon detector. Thus, an accurate model of this effect is necessary for precise calibration of the recoil energy measurement in low threshold phonon detectors. Furthermore, the sharpness of the defect creation threshold varies between materials. For a hard material such as diamond, the sharp threshold will cause a sudden onset of the energy loss effect, resulting in a prominent peak in the observed recoil spectrum just below the threshold displacement energy. We describe how this effect can be used to discriminate between nuclear and electron recoils using just the measured recoil spectrum.

• Dark matter searches and energy accumulation and release in materials

  Sergey Pereverzev

  SciPost Phys. Proc. 12, 009 (2023) · published 3 July 2023 | Toggle abstract · pdf

  Efforts to identify dark matter by detecting nuclear recoils produced by dark matter particles reveal low-energy backgrounds of unknown origin in different types of detectors. In many cases, energy accumulation and delayed burst-like releases of stored energy could provide an explanation. These dynamics follow Prigogine's ideas on systems with energy flow and the general Self-Organized Criticality scenario. We compare these models with properties of excess backgrounds in cryogenic solid-state detectors, relaxation processes in glasses and crystals, our observations of delayed luminescence in NaI(Tl), and make predictions for more phenomena present in these systems and in superconducting photon detectors and qubits. Experiments to create accurate phenomenological models are needed.

• Ionization efficiency at sub-keV energies for crystals and noble liquids

  Youssef Sarkis, Alexis A. Aguilar-Arevalo, Juan Carlos D'Olivo

  SciPost Phys. Proc. 12, 008 (2023) · published 3 July 2023 | Toggle abstract · pdf

  We study the ionization and light yields produced by nuclear recoils at low energies in pure crystals and noble liquids in the context of Lindhard's integral equation, incorporating the effects of binding energy, improved modeling of the electronic stopping, and electronic straggling. We consider three different models for the electronic stopping power that incorporate Coulomb repulsion effects at low energies, and Bohr electronic stripping for high energies. Finally, we discuss possible new effects near threshold.

• Underground laboratories

  Aldo Ianni

  SciPost Phys. Proc. 12, 007 (2023) · published 3 July 2023 | Toggle abstract · pdf

  A brief review on underground laboratories at the time of IDM 2022 is reported. General characteristics of these research infrastructures are discussed and a few highlights from different laboratories are reported. The idea of networking between underground laboratories is discussed.

  3 citations

• The status of the galactic center gamma-ray excess

  Dan Hooper

  SciPost Phys. Proc. 12, 006 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The Galactic Center Gamma-Ray Excess has a spectrum, angular distribution, and overall intensity that agree remarkably well with that expected from annihilating dark matter particles in the form of a $m_X \sim$ 50 GeV thermal relic. Previous claims that these photons are clustered on small angular scales or trace the distribution of known stellar populations once appeared to favor interpretations in which this signal originates from a large population of unresolved millisecond pulsars. More recent work, however, has overturned these conclusions, finding that the observed gamma-ray excess does not contain discernible small scale power, and is distributed with approximate spherical symmetry, not tracing any known stellar populations. In light of these results, it now appears significantly more likely that the Galactic Center Gamma-Ray Excess is produced by annihilating dark matter.

  2 citations