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arXiv · 1301.4290

First demonstration of a sub-keV electron recoil energy threshold in a liquid argon ionization chamber

S. Sangiorgio·T. H. Joshi·A. Bernstein·J. Coleman·M. Foxe·C. Hagmann·I. Jovanovic·K. Kazkaz·K. Mavrokoridis·V. Mozin·S. Pereverzev·P. Sorensen
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Abstract

We describe the first demonstration of a sub-keV electron recoil energy threshold in a dual-phase liquid argon time projection chamber. This is an important step in an effort to develop a detector capable of identifying the ionization signal resulting from nuclear recoils with energies of order a few keV and below. We obtained this result by observing the peaks in the energy spectrum at 2.82 keV and 0.27 keV, following the K- and L-shell electron capture decay of Ar-37, respectively. The Ar-37 source preparation is described in detail, since it enables calibration that may also prove useful in dark matter direct detection experiments. An internally placed Fe-55 x-ray source simultaneously provided another calibration point at 5.9 keV. We discuss the ionization yield and electron recombination in liquid argon at those three calibration energies.

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S. Sangiorgio, T. H. Joshi, A. Bernstein, J. Coleman, M. Foxe, C. Hagmann, I. Jovanovic, K. Kazkaz, K. Mavrokoridis, V. Mozin, S. Pereverzev, P. Sorensen. 2013-01-18. First demonstration of a sub-keV electron recoil energy threshold in a liquid argon ionization chamber. https://doi.org/10.1016/j.nima.2013.06.061

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