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arXiv · 2512.09820

Scintillation response of cryogenic CsI to few-keV and sub-keV nuclear recoils

J. I. Collar·C. M. Lewis·A. Simón·S. G. Yoon
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Abstract

Monochromatic neutron emissions from photonuclear sources $^{88}$Y/Be and $^{124}$Sb/Be are employed to obtain the response of pure (undoped) cesium iodide at 80 K. The use of a low-noise, high-quantum-efficiency avalanche photodiode in combination with a novel waveshifter results in a 70 eV analysis threshold. This reach allows to observe signals from sub-keV nuclear recoils originating in neutron scattering. The extracted quenching factor drops much faster towards low energy than the extrapolation of a model developed for room-temperature CsI[Na]. We comment on the impact of our measurement on planned use of cryogenic CsI in neutrino physics and dark matter experiments.

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J. I. Collar, C. M. Lewis, A. Simón, S. G. Yoon. 2025-12-10. Scintillation response of cryogenic CsI to few-keV and sub-keV nuclear recoils. https://arxiv.org/abs/2512.09820

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