1/f noise in the β decay of ${}_{}{}^{90}{}_{}{}^{}\mathrm{-}_{}^{90}{}_{}{}^{}$Y

The ${\mathrm{\beta }}^{\mathrm{-}}$ decay statistics of the radioactive ${}_{}{}^{90}{}_{}{}^{}\mathrm{-}_{}^{90}{}_{}{}^{}$Y source below 546 keV has been studied to search for the existence of 1/f noise. The presence of a flicker floor in a graph of relative Allan variance versus inverse mean count 〈${\mathit{M}}_{\mathit{T}}$${\mathrm{〉}}^{\mathrm{-}1}$ shows the existence of 1/f noise.