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Towards Characterization of sub-keV Nuclear Recoils in Liquid Argon

Abstract: Dual-phase noble liquids detectors have become a popular choice for WIMP dark matter experiments. More recently, they have been proposed also to search for coherent neutrino-nucleus scattering (CNNS). In both cases, the only signature in the detector is a low-energy nuclear recoil. For the most common WIMP scenarios, nuclear recoil energies between 10-100 keVr in liquid Ar or Xe are expected. Access to lower-energy recoils would allow to probe a broader range of light-mass WIMPs. For CNNS, sensitivity to nuclear recoils of a few hundred eVr is needed for reactor neutrino sources. In providing detector sensitivity at these low energies, it is critical to understand the detector response to nuclear recoils as compared to electron recoils i.e. by measuring the ionization yield of nuclear recoils in this regime. In this presentation, I will report on LLNL’s steps toward these goals using a dual-phase liquid-argon ionization chamber. I will present the detector design and operation and the latest results (sub-keV electron-recoil spectroscopy and single electron sensitivity). I will also discuss the measurement of the nuclear-recoil ionization yield in liquid argon, outlining in particular our work on a filtered and collimated neutron source that will provide access to argon nuclear recoils at ~7keVr and below.
Speaker: Samuele Sangiorgio - Lawrence Livermore National Laboratory
Speaker Bio: Samuele Sangiorgio received his Master degree in Physics at the University of Milano and his Ph.D. from the University of Insubria in Italy, where he developed an innovative detector technique for the rejection of radioactive contamination in bolometric experiments. As a postdoc at the University of Wisconsin-Madison, he led the effort to design and prototype the calibration system of the CUORE experiment, searching for neutrinoless double beta decay. He is currently a postdoc research staff at the Lawrence Livermore National Lab, where he focuses on the development of detectors for nuclear safeguards and non-proliferation using technologies that are also employed to answer the fundamental scientific questions about neutrinos and dark matter.
Poster Link: Poster
Presentation: Presentation on 2/20/2013 (PDF)