Search for Periodic Modulations of the Rate of Double-Beta Decay of ${}^{100}$Mo in the NEMO-3 Detector

Abstract

Double-beta decays of ${}^{100}$Mo from the 6.0195-year exposure of a 6.914 kg high-purity sample were recorded by the NEMO-3 experiment that searched for neutrinoless double-beta decays. These ultra-rare transitions to ${}^{100}$Ru have a half-life of approximately $7\times 10^{18}$ years, and have been used to conduct the first ever search for periodic variations of this decay mode. The Lomb-Scargle periodogram technique, and its error-weighted extension, were employed to look for periodic modulations of the half-life. Monte Carlo modeling was used to study the modulation sensitivity of the data over a broad range of amplitudes and frequencies. Data show no evidence of modulations with amplitude greater than 2.5% in the frequency range of $0.33225{\mathrm{y}}^{-1}$ to $365.25{\mathrm{y}}^{-1}$.