Detection of the natural α decay 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 T_1/2 = (1.8±0.2) × 10¹⁸ years and an energy release of Q= [2516.4±1.1 (stat.) ±1.2 (sys.) ] keV have been measured. New limits are also set on the half-lives of the other naturally occurring tungsten isotopes.