Low-energy neutrinos at off-axis from a standard beta beam

We discuss a scenario to extract up to 150 MeV neutrinos at a standard beta-beam facility using one and two detectors off-axis. In particular we show that the high-energy component of the neutrino fluxes can be subtracted through a specific combination of the response of two off-axis detectors. A systematic analysis of the neutrino fluxes using different detector geometries is presented, as well as a comparison with the expected fluxes at a low-energy beta-beam facility. The presented option could offer an alternative way to perform low-energy neutrino experiments.

Figure 1

The location of the single off-axis detector $D$ is shown relative to the standard beta-beam storage ring with straight section $AO$.

Figure 2

Off-axis antineutrino fluxes ($\times 20$) evaluated at point $D$ of Fig. 1 for two different ion boosts and neutrino energy cuts. The neutrino flux from a low-energy beta-beam (LE) at $\gamma =14$ is shown for comparison.

Figure 3

Schematic view of the two off-axis detector locations, $D_1$ and $D_2$, relative to the straight section of the beta-beam storage ring, $AO$.

Figure 4

Comparison of the different low-energy neutrino fluxes (left panel) and the corresponding number of antineutrino-hydrogen events for the water detectors (right panel). The presented results are obtained for a standard beta-beam exploiting two detectors off-axis (Fig. 3) and the subtraction method described in the text (these fluxes are multiplied by 6). The different curves correspond to four different detector geometries, namely, the cylinder-sausage ($d_1$), the cylinder-normal ($d_2$), the cylinder-disc ($d_3$), and the spherical (Table ). As a comparison, the fluxes from an LE beta-beam, and for a single off-axis detector $d_2$ as described in Sec. 2b (HE), are given. The last flux is multiplied by 20.

Figure 5

Neutrino fluxes obtained by placing two detectors $d_1$ (Table ) off-axis and using the subtraction method described in the text. The different curves correspond to two ion boosts and m aximum neutrino energy cutoff. The first detector is located at $y=5\mathrm{m}$.

Figure 6

Same as Fig. 5 but for different $y$ locations.