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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.
Uncertainty in the operating temperatures of Oklo reactor zones impacts the precision of bounds derived for time variation of the fine structure constant $alpha$. Improved $^{176}$Lu/$^{175}$Lu thermometry has been discussed but its usefulness may be
From the discovery of the neutrino to the precision neutrino oscillation measurements in KamLAND, nuclear reactors have proven to be an important source of antineutrinos. As their power and our knowledge of neutrino physics has increased, more sensit
We present techniques that allow for $alpha$-cluster channels with realistic $alpha$-particle wave functions from No Core Shell Model calculations to be constructed. We compare results of several clustering calculations with realistic $alpha$ wave fu
The 4He total photoabsorption cross section is calculated with the realistic nucleon-nucleon potential Argonne V18 and the three-nucleon force (3NF) Urbana IX. Final state interaction is included rigorously via the Lorentz Integral Transform method.
In the context of f(R)=R + alpha R^2 gravity, we study the existence of neutron and quark stars with no intermediate approximations in the generalised system of Tolman-Oppenheimer-Volkov equations. Analysis shows that for positive alphas the scalar c