Detection of the natural α decay of tungsten -: art. no. 064606

The natural alpha-decay of W-180 has been unambiguously detected for the first time. The alpha peak is found in a (gamma, beta, 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)x10(18) 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.