An algorithm for filtering detector instabilities in search of novel non-exponential decay and in conventional half-life determinations.

Recent reports of Solar modulation of beta-decay have reignited interest in whether or not radioactive half-lives are constants. A numerical approach for filtering instrumental effects on residuals is developed, using correlations with atmospheric conditions recorded while counting204 Tl emissions with a Geiger-Müller counter. Half-life oscillations and detection efficiency oscillations can be separated provided their periods are substantially different. A partial uncertainty budget for the204 Tl half-life shows significant decreases to medium-frequency instabilities correlated with pressure and temperature, which suggests that further development may aid general improvements in half-life determinations.