First Probe of Sub-GeV Dark Matter beyond the Cosmological Expectation with the COHERENT CsI Detector at the SNS

The COHERENT Collaboration searched for scalar dark matter particles produced at the Spallation Neutron Source with masses between 1 and 220 MeV/c(2) using a CsI[Na] scintillation detector sensitive to nuclear recoils above 9 keV(nr). No evidence for dark matter is found and we thus place limits on allowed parameter space. With this low-threshold detector, we are sensitive to coherent elastic scattering between dark matter and nuclei. The cross section for this process is orders of magnitude higher than for other processes historically used for accelerator-based direct-detection searches so that our small, 14.6 kg detector significantly improves on past constraints. At peak sensitivity, we reject the flux consistent with the cosmologically observed dark-matter concentration for all coupling constants alpha(D) < 0.64, assuming a scalar dark-matter particle. We also calculate the sensitivity of future COHERENT detectors to dark-matter signals which will ambitiously test multiple dark-matter spin scenarios.

Automated summary

The COHERENT Collaboration conducted a search for scalar dark matter particles at the Spallation Neutron Source. No evidence of dark matter was found, leading to constraints on the allowed parameter space. Utilizing a low-threshold detector, they improved upon previous constraints by detecting coherent elastic scattering between dark matter and nuclei with a significantly higher cross section. They also calculated the sensitivity of future COHERENT detectors to test various dark matter spin scenarios.