Toward a neutrino-limited dark matter search with crystalline xenon

Experiments searching for weakly interacting massive particle dark matter are now detecting background events from solar neutrino-electron scattering. However, the dominant radioactive background in state-of-the-art experiments such as LZ and XENONnT is beta decays from radon contamination. In spite of careful detector material screening, radon progenitor atoms are ubiquitous and long-lived, and radon is extremely soluble in liquid xenon. We propose a change of phase and demonstrate that crystalline xenon offers more than a factor <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mo>×</a:mo><a:mn>500</a:mn></a:mrow></a:math> exclusion against radon ingress, compared with the liquid state. This level of radon exclusion would allow crystallized versions of existing experiments to probe spin-independent cross sections near <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:msup><c:mrow><c:mn>10</c:mn></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>47</c:mn></c:mrow></c:msup><c:mtext> </c:mtext><c:mtext> </c:mtext><c:msup><c:mrow><c:mi>cm</c:mi></c:mrow><c:mrow><c:mn>2</c:mn></c:mrow></c:msup></c:mrow></c:math> in roughly 11 years, as opposed to the 35 years required otherwise. Published by the American Physical Society 2024