Gallium experiments with artificial neutrino sources as a tool for investigation of transition to sterile states

Abstract

We propose to place a very intense source of 51Cr at the center of a 50-tonne target of gallium metal that is divided into two concentric spherical zones and to measure the neutrino capture rate in each zone. This experiment can set limits on transitions from active to sterile neutrinos with Delta m^2 ~ 1 eV^2 with a sensitivity to disappearance of electron neutrinos of a few percent.

Figures (4)

• Figure 1: Region of allowed mixing parameters inferred from gallium source experiments assuming oscillations to a sterile neutrino. Plus sign at $\Delta m^2=2.15$ eV$^2$ and $\sin^2 2\theta=0.24$ indicates the best-fit point.
• Figure 2: Schematic drawing of proposed neutrino source experiment. $R_1$ and $R_2$ are the ratios of measured capture rate to predicted rate in the inner and outer zones, respectively. Outer radii $r$ of the two zones and diameter $\phi$ of source reentrant tube are indicated in mm.
• Figure 3: Ratio of rates in the outer and inner zones versus $\Delta m^2$ for the case of $\sin^2 2\theta = 0.3$.
• Figure 4: Regions of allowed mixing parameters for various possible outcomes of new two-zone Ga experiment. $R_1$ and $R_2$ are the ratios of measured rate to predicted rate in the inner and outer zones, respectively. Plus sign indicates the best-fit point.