From NigelJTSmith on Twitter: A slug of radon in the ⁦@TRIUMFLab⁩ cloud chamber, showing the alpha decays from the chain (thick tracks). Radon is a challenging background for dark matter detectors as it leads to nuclear recoil backgrounds that mimic the signal. https://twitter.com/NigelJTSmith/status/1621711578939949058/video/1