Sources of the systematic errors in measurements of Po-214 decay half-life time variations at the Baksan deep underground experiments

TL;DR

This study investigates systematic errors in Po-214 half-life measurements at the Baksan underground experiments, identifying potential sources of error and observing annual and daily variations in the measured half-life.

Contribution

The paper introduces improved measurement sensitivity and analyzes systematic error sources affecting Po-214 half-life measurements, revealing periodic variations.

Findings

Detected annual variation in half-life with amplitude ~7 x 10^{-4}

Observed daily variation with amplitude ~10 x 10^{-4}

Measured average half-life as 163.45 ms

Abstract

The design changes of the Baksan low-background TAU-1 and TAU-2 set-ups allowed to improve a sensitivity of Po-214 half-life (\tau) measurements up to the 2.5 x 10^{-4} are described. Different possible sources of systematic errors influencing on the $\tau$-value are studed. An annual variation of Po-214 half-life time measurements with an amplitude of A=(6.9 \pm 3) x 10^{-4} and a phase of (\phi=93 \pm 10) days was found in a sequence of the week-collected \tau-values obtained from the TAU-2 data sample with total duration of 480 days. 24 hours' variation of the \tau-value measurements with an amplitude of A=(10.0 \pm 2.6) x 10^{-4} and phase of (\phi=1 \pm 0.5) hours was found in a solar day 1 hour step \tau-value sequence formed from the same data sample. It was found that the Po-214 half-life averaged at 480 days is equal to (163.45 \pm 0.04) mks.