Results of the engineering run of the coherent neutrino nucleus interaction experiment (CONNIE)

The CONNIE detector prototype is operating at a distance of 30 m from the core of a 3.8 GWth nuclear reactor with the goal of establishing Charge-Coupled Devices (CCD) as a new technology for the detection of coherent elastic neutrino-nucleus scattering. We report on the results of the engineering run with an active mass of 4 g of silicon. The CCD array is described, and the performance observed during the first year is discussed. A compact passive shield was deployed around the detector, producing an order of magnitude reduction in the background rate. The remaining background observed during the run was stable, and dominated by internal contamination in the detector packaging materials. The in-situ calibration of the detector using X-ray lines from fluorescence demonstrates good stability of the readout system. The event rates with the reactor ON and OFF are compared, and no excess is observed coming from nuclear fission at the power plant. The upper limit for the neutrino event rate is set two orders of magnitude above the expectations for the standard model. The results demonstrate the cryogenic CCD-based detector can be remotely operated at the reactor site with stable noise below2 e RMS and stable background rates. The success of the engineering test provides a clear path for the upgraded 100 g detector to be deployed during 2016.Fil: Aguilar Arevalo, A.. Universidad Nacional Autónoma de México; MéxicoFil: Bertou, Xavier Pierre Louis. Comisión Nacional de Energía Atómica; Argentina. Comisión Nacional de Energía Atómica. Fundación José A. Balseiro; ArgentinaFil: Bonifazi, C.. Universidade Federal do Rio de Janeiro; BrasilFil: Butner, M.. Fermi National Accelerator Laboratory; Estados UnidosFil: Cancelo, G.. Fermi National Accelerator Laboratory; Estados UnidosFil: Castañeda Vazquez, A.. Universidad Nacional Autónoma de México; MéxicoFil: Cervantes Vergara, B.. Universidad Nacional Autónoma de México; MéxicoFil: Chavez, C. R.. Universidad Nacional de Asunción; ParaguayFil: Da Motta, H.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: D'Olivo, J. C.. Universidad Nacional Autónoma de México; MéxicoFil: Dos Anjos, J.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Estrada, J.. Fermi National Accelerator Laboratory; Estados UnidosFil: Fernández Moroni, Guillermo. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ford, R.. Fermi National Accelerator Laboratory; Estados UnidosFil: Foguel, A.. Centro Brasileiro de Pesquisas Físicas; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Hernandez Torres, K. P.. Universidad Nacional Autónoma de México; MéxicoFil: Izraelevitch, F.. Fermi National Accelerator Laboratory; Estados UnidosFil: Kavner, A.. University of Michigan; Estados UnidosFil: Kilminster, B.. Universitat Zurich; SuizaFil: Kuk, K.. Fermi National Accelerator Laboratory; Estados UnidosFil: Lima Jr, H. P.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Makler, M.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Molina, J.. Universidad Nacional de Asunción; ParaguayFil: Moreno Granados, G.. Universidad Nacional Autónoma de México; MéxicoFil: Moro, Juan Manuel. Universidad Nacional del Sur. Departamento de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Paolini, Eduardo Emilio. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto ; ArgentinaFil: Sofo Haro, Miguel Francisco. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Trillaud, F.. Universidad Nacional Autónoma de México; MéxicoFil: Wagner, S.. Centro Brasileiro de Pesquisas Físicas; Brasil. Pontificia Universidade Católica do Rio Grande do Sul; Brasi

Search for low-mass WIMPs in a 0.6 kg day exposure of the DAMIC experiment at SNOLAB

We present results of a dark matter search performed with a 0.6 kg day exposure of the DAMIC experiment at the SNOLAB underground laboratory. We measure the energy spectrum of ionization events in the bulk silicon of charge-coupled devices down to a signal of 60 eV electron equivalent. The data are consistent with radiogenic backgrounds, and constraints on the spin-independent WIMP-nucleon elastic-scattering cross section are accordingly placed. A region of parameter space relevant to the potential signal from the CDMS-II Si experiment is excluded using the same target for the first time. This result obtained with a limited exposure demonstrates the potential to explore the low-mass WIMP region (<10 GeV/$c^{2}$) of the upcoming DAMIC100, a 100 g detector currently being installed in SNOLAB.Comment: 11 pages, 11 figure

Correspondence: Strongly-driven Re + CO2 redox reaction at high-pressure and high-temperature

Santamaría-Perez, D.; Mcguire, C.; Makhluf, A.; Kavner, A.; Chulia-Jordan, R.; Jorda Moret, JL.; Rey Garcia, F.... (2016). Correspondence: Strongly-driven Re + CO2 redox reaction at high-pressure and high-temperature. Nature Communications. 7:1-3. doi:10.1038/ncomms13647S137Yoo, C. S. et al. Crystal structure of carbon dioxide at high pressure: “superhard” polymeric carbon dioxide. Phys. Rev. Lett. 83, 5527–5530 (1999).Santoro, M. et al. Partially collapsed cristobalite structure in the non molecular phase V in CO2 . Proc. Natl Acad. Sci. 109, 5176–5179 (2012).Datchi, F., Mallick, B., Salamat, A. & Ninet, S. Structure of polymeric carbon dioxide CO2-V. Phys. Rev. Lett. 108, 125701 (2012).Santoro, M. et al. Silicon carbonate phase formed from carbon dioxide and silica under pressure. Proc. Natl Acad. Sci. 108, 7689–7692 (2011).Santoro, M. et al. Carbon enters silica forming a cristobalite-type CO2.SiO2 solid solution. Nat. Commun. 5, 3761 (2014).Corma, A., Rey, F., Rius, J., Sabater, M. J. & Valencia, S. Supramolecular self-assembled molecules as organic directing agent for synthesis of zeolites. Nature 431, 287–290 (2004).Guth, J.-L., Kessler, H. & Wey, R. in Studies in Surface Science and Catalysis Vol. 28 (eds Murakami, Y., Iijima, A. & Ward, J. W.) 121 (Kodansha-Elsevier, 1986).Santamaria-Perez, D. et al. Exploring the chemical reactivity between carbon dioxide and three transition metals (Au, Pt, and Re) at high-pressure high-temperature conditions. Inorg. Chem. 55, 10793–10799 (2016).Magneli, A. Studies on rhenium oxides. Acta Chem. Scand. 11, 28–33 (1957)