Detection of the naturalαdecay of tungsten

The natural α-decay of ¹⁸⁰W has been unambiguously detected for the first time. The α peak is found in a (γ, β, and neutron)-free background spectrum. This has been achieved by the simultaneous measurement of phonon and light signals with the CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) cryogenic detectors. A half-life of T1∕2=(1.8±0.2)×10¹⁸0.3em0exyears and an energy release of Q=[2516.4±1.1(stat.)±1.2(sys.)]0.3em0exkeV have been measured. New limits are also set on the half-lives of the other naturally occurring tungsten isotopes.