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Title: Modeling ionization and recombination from low energy nuclear recoils in liquid argon

Coherent neutrino-nucleus scattering (CNNS) is an as-yet undetected, flavor-independent neutrino interaction predicted by the Standard Model. CNNS is a flavor-blind interaction, which offers potential benefits for its use in nonproliferation (nuclear reactor monitoring) and astrophysics (supernova and solar neutrinos) applications. One challenge with detecting CNNS is the low energy deposition associated with a typical CNNS nuclear recoil. In addition, nuclear recoils are predicted to result in lower ionization yields than those produced by electron recoils of the same energy. This ratio of nuclear- and electron-induced ionization, known as the nuclear quenching factor, is unknown at energies typical for CNNS interactions in liquid xenon (LXe) and liquid argon (LAr), detector media being considered for CNNS detection. While there have been recent measurements [1] of the ionization yield from nuclear recoils in LAr, there is no universal model for nuclear quenching and ionization yield. For this reason, a Monte Carlo simulation has been developed to predict the ionization yield at sub-10 keV energies. The local ionization yield of a recoiling atom in the medium is calculated first. The ejected electrons are subsequently tracked in the electric field resulting from both the local electric charges and the externally applied drift field. The dependencemore » of the ionization yield on the drift electric field is obtained by combining the calculated ionization yield for the initial collision cascade with the electron escape probability. An updated estimate of the CNNS signal expected in a LAr detector operated near a nuclear power reactor is presented.« less
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Journal Article
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Journal Name: Astroparticle Physics, 69:24-29
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
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Country of Publication:
United States
Low-Energy Ionization; Liquid Argon; Neutrino-Nucleus; Coherent Neutrino-Nucleus Scattering; CNNS; Liquid Xenon; CNNS Detection