Lutetium thermometry for Oklo natural reactors: a new look at old data

Abstract

Lutetium thermometry has been used to analyze Oklo natural nuclear reactor zones but leads to widely varying and puzzling predictions for the temperatures $T_O$ which in turn impacts bounds on time variation of the fine structure constant $\alpha$. We revisit results for reactor zone RZ10 in light of new measurements of the isomer branching ratio $B^g$ in ${}^{175}$Lu neutron capture at 5 and 25 keV. We recalculate predictions for $T_O$ as a function of $B^g$ using realistic models of the Oklo neutron flux. We find $T_O=100\pm 30$ C using a new value of $B^g$, in contrast to $350<T_O<500$ C using the evaluated value at thermal energy. Lutetium thermometry can be applicable to analyses of Oklo reactor data, but a better measurement of $B^g$ with thermal neutrons is needed to confirm the reliability of temperature predictions.

arXiv comment7 pages, 2 figures

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Cited by in corpus (3)

• Oklo reactors and implications for nuclear science
• Gamma-ray fluxes in Oklo natural reactors
• La138/139 Isotopic Data and Neutron Fluences for Oklo RZ10 Reactor