High-precision measurement of $^{215}$Po half-life via delayed-coincidence analysis

We performed a high-precision study of the $^{215}$ Po $α$-decay using a LaBr$_3$ scintillating detector in a low-background environment. The $^{227}$Ac intrinsic contamination in the LaBr$_3$ crystal undergoes a decay chain, producing the intermediate pair of $^{219}$Rn$\rightarrow^{215}$Po$\rightarrow^{211}$Pb decays. The fast time response and good energy resolution of the detector allow for extracting the short half-life of $^{215}$Po from the time correlation of the two subsequent $α$-decays by using the delayed coincidence method. Thanks to high statistics and a comprehensive uncertainty assessment, we obtain the most precise half-life value to date of $^{215}$Po, corresponding to $1.77804\pm0.00091$(stat.)$\pm0.00067$(syst.) ms.