Constraints on the decay of \(^{180m}\)Ta

\(^{180m}\)Ta is a rare nuclear isomer whose decay has never been observed. Its remarkably long lifetime surpasses the half-lives of all other known \(\beta\) and electron capture decays due to the large K-spin differences and small energy differences between the isomeric and lower energy states. Detecting its decay presents a significant experimental challenge but could shed light on neutrino-induced nucleosynthesis mechanisms, the nature of dark matter and K-spin violation. For this study, we repurposed the MAJORANA DEMONSTRATOR, an experimental search for the neutrinoless double-beta decay of \(^{76}\)Ge using an array of high-purity germanium detectors, to search for the decay of \(^{180m}\)Ta. More than 17 kilograms, the largest amount of tantalum metal ever used for such a search was installed within the ultra-low background detector array. In this paper we present results from the first year of Ta data taking and provide an updated limit for the \(^{180m}\)Ta half-life on the different decay channels. With new limits up to 1.5 x \(10^{19}\) years, we improved existing limits by one to two orders of magnitude. This result is the most sensitive search for a single \(\beta\) and electron capture decay ever achieved.