A novel method of identification of in-ring decay and its application in the half-life estimates of 94mRu44+

Isochronous Mass Spectrometry is a practical approach for studying decays of short-lived isomers. However, solely relying on the time stamps between the isomer and ground state does not provide clear sign of decay. To address this issue, we proposed a method for extracting decay time point by analyzing the residuals of time stamps within a window of ($20\mu s$, $180\mu s$) after the start of data acquisition. Decay events out of the window were disregarded due to poor accuracy of revolution time. In this paper, we propose a novel approach based on the discrete Fourier transform technique, which was tested by simulation data. We found that the accuracy of the decay time point can be improved, leading to an expanded window of ($15\mu s$, $185\mu s$). Furthermore, as the novel method was applied to experimental data, additional five decay events were identified. The newly determined half-life of ${}^{94m}$Ru${}^{44+}$ is consistent with the previous value.