Empirical decomposition and error propagation of medium-term instabilities in half-life determinations

Abstract A least-squares fit of exponential functions to a measured radioactive decay rate curve provides an estimate the half-life and its statistical uncertainty in assumption that all deviations from theoretical are purely random nature. The result may be biased error underestimated as soon experiment suffers instabilities exceed duration individual measurements. Contrary long-term systematic errors, medium-frequency cyclic perturbations observable autocorrelated structures residuals. In this work, empirical decomposition algorithm is used separate effects component residuals, such custom propagation factors can calculated. study made for sine square wave perturbations. method demonstrated on synthetic spectrum, time series solar neutrino detection rates, two experimental curves 134 Cs ionisation chamber.