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Investigated in this work were sensitivities of a prototype detector for the detection of low-mass dark matter particles produced at the Spallation Neutron Source at the Oak Ridge National Laboratory in 2 years of data taking. The presumed prototype consisted of 10 kg undoped CsI or NaI scintillation crystals directly coupled with SiPM arrays operated at 77 K. Compared to the COHERENT CsI(Na) detector, a much higher light yield was assumed for the prototype. An experiment with a cylindrical 1 kg undoped CsI crystal coupled directly to two photomultiplier tubes at about 77 K was conducted as the first step to verify the idea. A light yield of 26.0 ± 0.4 photoelectrons per keV electron-equivalent was achieved. This eliminated the concern of self light absorption in large crystals raised in some of the early studies.

We report on the technical design and expected performance of a 592 kg heavy-water-Cherenkov detector to measure the absolute neutrino flux from the pion-decay-at-rest neutrino source at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The detector will be located roughly 20 m from the SNS target and will measure the neutrino flux with better than 5 % statistical uncertainty in 2 years. This heavy-water detector will serve as the first module of a two-module detector system to ultimately measure the neutrino flux to 2-3 % at both the First Target Station and the planned Second Target Station of the SNS. This detector will significantly reduce a dominant systematic uncertainty for neutrino cross-section measurements at the SNS, increasing the sensitivity of searches for new physics.

The light yield of an undoped CsI crystal at about 77 Kelvin was measured to be $$33.5 \, \pm \, 0.7$$ 33.5 ± 0.7  photo-electrons (PE) per keV electron-equivalent (keVee) in the energy range of [13, 60] keVee using X and $$\gamma $$ γ -rays from an $$^{241}$$ 241 Am radioactive source. Based on this experimental result, the performance of 10 kg cryogenic inorganic scintillating crystals coupled to SiPM arrays to probe non-standard neutrino interactions through the detection of coherent elastic neutrino-nucleus scatterings at the spallation neutron source, Oak Ridge National Laboratory, was examined in detail.

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