1202.3682 (C. R. Gould et al.)

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

C. R. Gould, E. I. Sharapov

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.

View original: http://arxiv.org/abs/1202.3682