Current status of new SAGE project with 51 Cr neutrino source
A very short-baseline neutrino oscillation experiment with an intense 51 Cr neutrino source is currently under construction at the Baksan Neutrino Observatory of the Institute for Nuclear Research RAS (BNO). The experiment, which is based on the existing SAGE experiment, will use an upgraded Gallium-Germanium Neutrino Telescope (GGNT) and an artificial 51 Cr neutrino source with activity ~3 MCi to search for transitions of active neutrinos to sterile states with Δm 2 ~1 eV 2 . The neutrino source will be placed in the center of a liquid Ga metal target that is divided into two concentric zones, internal and external. The average path length of neutrinos in each zone will be the same and the neutrino capture rate will be measured separately in each zone. The oscillation signature, which comes from the ratio of events in the near and far gallium volumes, will be largely free of systematic errors, such as may occur from cross section and source strength uncertainties, and will provide a clean signal of electron neutrino disappearance into a sterile state at baselines of about 0.6 and 2.0 m. The sensitivity to the disappearance of electron neutrinos is expected to be a few percent. Construction of this set of new facilities, including a two-zone tank for irradiation of 50 tons of Ga metal with the intense 51 Cr source, as well as additional modules of the GGNT counting and extraction systems, is close to completion. In order to check the new facilities they will first be used for SAGE solar neutrino measurements.