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arXiv · 1609.03725

Search for the decay of nature's rarest isotope $^{\rm {180m}}$Ta

Björn Lehnert·Mikael Hult·Guillaume Lutter·Kai Zuber
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Abstract

$^{\rm {180m}}$Ta is the rarest naturally occurring quasi-stable isotope and the longest lived metastable state which is known. Its possible decay via the $β^-$ or the electron capture channel has never been observed. This article presents a search for the decay of $^{\rm {180m}}$Ta with an ultra low background Sandwich HPGe gamma spectrometry setup in the HADES underground laboratory. No signal is observed and improved lower partial half-life limits are set with a Bayesian analysis to $5.8\cdot10^{16}$ yr for the $β^-$ channel and $2.0\cdot10^{17}$ yr for the electron capture channel (90% credibility). The total half-life of $^{\rm {180m}}$Ta is longer than $4.5\cdot10^{16}$ yr. This is more than a factor of two improvement compared to previous searches.

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Björn Lehnert, Mikael Hult, Guillaume Lutter, Kai Zuber. 2016-11-07. Search for the decay of nature's rarest isotope $^{\rm {180m}}$Ta. https://doi.org/10.1103/physrevc.95.044306

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