Time-variability of alpha from realistic models of Oklo reactors

Abstract

We reanalyze Oklo ${}^{149}$Sm data using realistic models of the natural nuclear reactors. Disagreements among recent Oklo determinations of the time evolution of $\alpha$, the electromagnetic fine structure constant, are shown to be due to different reactor models, which led to different neutron spectra used in the calculations. We use known Oklo reactor epithermal spectral indices as criteria for selecting realistic reactor models. Two Oklo reactors, RZ2 and RZ10, were modeled with MCNP. The resulting neutron spectra were used to calculate the change in the ${}^{149}$Sm effective neutron capture cross section as a function of a possible shift in the energy of the 97.3-meV resonance. We independently deduce ancient ${}^{149}$Sm effective cross sections, and use these values to set limits on the time-variation of $\alpha$. Our study resolves a contradictory situation with previous Oklo $\alpha$-results. Our suggested $2\sigma$ bound on a possible time variation of $\alpha$ over two billion years is stringent: $-0.24\times 10^{-7}\le \frac{\Delta \alpha }{\alpha }\le 0.11\times 10^{-7}$, but model dependent in that it assumes only $\alpha$ has varied over time.

14 pages, 4 figures. Corrections: minus sign missing in equation 32, changed sign of change in alpha in equations 33 and 34. Also added two new references and corrected minor typographical errors

References in corpus (9)

• The fundamental constants and their variation: observational status and theoretical motivations
• Further Evidence for Cosmological Evolution of the Fine Structure Constant
• The Oklo bound on the time variation of the fine-structure constant revisited
• Limits on the time variation of the electromagnetic fine-structure constant in the low energy limit from absorption lines in the spectra of distant quasars
• New limit on the present temporal variation of the fine structure constant
• The Cosmological Evolution of the Nucleon Mass and the Electroweak Coupling Constants
• The nuclear interaction at Oklo 2 billion years ago
• Implications of Gauge Unification for Time Variation of the Fine Structure Constant
• Neutron Moderation in the Oklo Natural Reactor and the Time Variation of alpha

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