2012 journal article

Lu-176/Lu-175 thermometry for the Oklo natural reactors: A new examination of old data


By: C. Gould & E. Sharapov*

Source: Web Of Science
Added: August 6, 2018

Background: 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 $\ensuremath{\alpha}$.Purpose: 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.Method: We recalculate predictions for ${T}_{O}$ as a function of ${B}^{g}$ using realistic models of the Oklo neutron flux.Results: We find ${T}_{O}=100\ifmmode\pm\else\textpm\fi{}30$ ${}^{\ensuremath{\circ}}$C using a new value of ${B}^{g}$, in contrast to $350<{T}_{O}<500$ ${}^{\ensuremath{\circ}}$C using the evaluated value at thermal energy.Conclusions: 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.