# Results from the Baksan Experiment on Sterile Neutrinos (BEST)

B.T. Cleveland, S.N. Danshin, H. Ejiri, S.R. Elliott, D. Frekers, V.N. Gavrin, V.V. Gorbachev, D.S. Gorbunov, W.C. Haxton, et al.
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Abstract

The Baksan Experiment on Sterile Transitions (BEST) was designed to investigate the deficit of electron neutrinos, , observed in previous gallium-based radiochemical measurements with high-intensity neutrino sources, commonly referred to as the \textit{gallium anomaly}, which could be interpreted as evidence for oscillations between and sterile neutrino () states. A source was placed at the center of two nested Ga volumes and measurements were made of the production of \nuc{71}{Ge} through the charged current reaction, ,e, at two average distances. The measured production rates for the inner and the outer targets respectively are () and () atoms of . The ratio () of the measured rate of production at each distance to the expected rate from the known cross section and experimental efficiencies are and . The ratio of the outer to the inner result is 0.970.07, which is consistent with unity within uncertainty. The rates at each distance were found to be similar, but 20-24\% lower than expected, thus reaffirming the anomaly. These results are consistent with oscillations with a relatively large (1 eV) and mixing sin (0.4).

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