Electromagnetic characterization of the 990 ton gapless magnets for the OPERA experiment

The instrumented targets of the OPERA neutrino experiment are complemented by two massive spectrometers based on gapless iron magnets. In 2006, a systematic assessment of their electromagnetic properties have been carried out. In this document, we report the results of such characterization and demonstrate that the achieved performance fulfill the physics requirements for the study of νμ→ντ oscillations

Alternative Fourier Expansions for Inverse Square Law Forces

Few-body problems involving Coulomb or gravitational interactions between pairs of particles, whether in classical or quantum physics, are generally handled through a standard multipole expansion of the two-body potentials. We discuss an alternative based on a compact, cylindrical Green's function expansion that should have wide applicability throughout physics. Two-electron "direct" and "exchange" integrals in many-electron quantum systems are evaluated to illustrate the procedure which is more compact than the standard one using Wigner coefficients and Slater integrals.Comment: 10 pages, latex/Revtex4, 1 figure

The instrumented magnets for the OPERA experiment: construction and commissioning

The design and construction of the 990-ton gapless iron magnets for the OPERA experiment represent a major challenge from the point of view of mechanics, electric and heat engineering. Two of such magnets have been built in a deep underground hall of the Gran Sasso laboratories between 2003 and 2006 and they have been switched on for the first time in March 2006. In this paper we discuss the construction and characterization of these devices. First experience with the CNGS beam are also reported. © 2007 Elsevier B.V. All rights reserved

Tagging and localization of ionizing events using NbSi transition edge phonon sensors for dark matter searches

In the context of direct searches of sub-GeV dark matter particles with germanium detectors, the EDELWEISS collaboration has tested a new technique to tag ionizing events using NbSi transition edge athermal phonon sensors. The emission of the athermal phonons generated by the Neganov-Trofimov-Luke effect associated with the drift of electrons and holes through the detectors is used to tag ionization events generated in specific parts of the detector localized in front of the NbSi sensor and to reject by more than a factor 5 [at 90% confidence level (CL)] the background from heat-only events that dominates the spectrum above 3 keV. This method is able to improve by a factor of 2.8 the previous limit on spinindependent interactions of 1 GeV=c2 weakly interacting massive particles obtained with the same detector and dataset but without this tagging technique.The help of the technical staff of the Laboratoire Souterrain de Modane and the participant laboratories is gratefully acknowledged. The EDELWEISS project is supported in part by the French Agence Nationale pour la Recherche (ANR-21-CE31-0004), by the P2IO LabEx (ANR-10-LABX-0038) in the framework “Investissements d’Avenir” (ANR-11-IDEX-0003-01), and the LabEx Lyon Institute of Origins (ANR-10-LABX-0066) within the framework of the program France 2030, also operated by the National Research Agency of France. B. J. Kavanagh thanks the Spanish Agencia Estatal de Investigación (AEI, MICIU) for the support to the Unidad de Excelencia María de Maeztu Instituto de Física de Cantabria, Ref. MDM-2017-0765. B. J. K. also acknowledges funding from the Ramón y Cajal Grant RYC2021-034757-I, financed by MCIN/AEI/10.13039/ 501100011033 and by the European Union “NextGenerationEU”/PRTR

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 particle interactions via Migdal effect with masses between 32 MeV · c−2 to 2 GeV · 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 eVee (102.58 eV at 66 V) and an analysis threshold of 30 eVee. 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 cm2 and masses between 32 and 100 MeV · c−2. The achieved low threshold with the NbSi sensor shows the relevance of its use for out-of-equilibrium phonon sensitive devices for low-mass dark matter searches.The EDELWEISS project is supported in part by the French Agence Nationale pour la Recherche (ANR) and the LabEx Lyon Institute of Origins (ANR-10-LABX 0066) of the Universit´e de Lyon within the program “Investissements d’Avenir” (ANR-11-IDEX-00007), by the P2IO LabEx (ANR-10-LABX-0038) in the framework “Investissements d’Avenir” (ANR-11-IDEX-0003-01) managed by the ANR (France), and the Russian Foundation for Basic Research (Grant No. 18-02- 00159). This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 838537. B. J. K. thanks the Spanish Agencia Estatal de Investigación (AEI, MICIU) for the support to the Unidad de Excelencia María de Maeztu Instituto de Física de Cantabria, Ref. MDM-2017-0765. We thank J. P. Lopez (IP2I) and the Physics Department of Universit´e Lyon 1 for their contribution to the radioactive sources