α activity of natural tungsten isotopes

Abstract

The indication for the $\ensuremath{\alpha}$ decay of ${}^{180}\mathrm{W}$ with a half-life ${T}_{1/2}^{\ensuremath{\alpha}}{=1.1}_{\ensuremath{-}0.4}^{+0.8}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.3(\mathrm{syst})\ifmmode\times\else\texttimes\fi{}{10}^{18}$ yr has been observed for the first time with the help of the superlow background ${}^{116}{\mathrm{CdWO}}_{4}$ crystal scintillators. In a conservative approach the lower limit on half-life of ${}^{180}\mathrm{W}$ has been established as ${T}_{1/2}^{\ensuremath{\alpha}}{(}^{180}\mathrm{W})>~0.7\ifmmode\times\else\texttimes\fi{}{10}^{18}$ yr at 90% C.L. In addition, new ${T}_{1/2}^{\ensuremath{\alpha}}$ bounds were set for $\ensuremath{\alpha}$ decay of ${}^{182}\mathrm{W},{}^{183}\mathrm{W},{}^{184}\mathrm{W},$ and ${}^{186}\mathrm{W}$ at the level of ${10}^{20}$ yr.