The gamma = 100 Beta-Beam revisited

TL;DR

This study compares gamma=100 Beta-Beam neutrino setups using 8B/8Li decays to standard 18Ne/6He setups, analyzing their sensitivity to neutrino parameters and background suppression requirements.

Contribution

It demonstrates that 8B and 8Li based setups can independently detect the mass hierarchy due to stronger matter effects, highlighting their potential advantages over standard configurations.

Findings

8B/8Li setups are sensitive to mass hierarchy at sin^2 2theta_{13} > 10^-2

Higher energy neutrinos require larger fluxes for comparable sensitivity

A background suppression factor of 10^-4 effectively eliminates atmospheric background

Abstract

We study the performance of gamma = 100 Beta-Beam setups based on the decays of 8B and 8Li as a function of the achievable production fluxes and compare them with the standard setups based on 18Ne and 6He decays. For the standard setup we also investigate the physics potential for reduced 18Ne fluxes, since it seems experimentally challenging to achieve the baseline numbers. We find that, contrary to the standard setup, setups based in 8B and 8Li can be sensitive to the mass hierarchy down to values of sin^2 2theta_{13} > 10^-2 by themselves, due to the stronger matter effects granted by the higher energy of the neutrinos. On the other hand, the longer baseline required for neutrinos to oscillate at these higher energies reduces the statistics at the detector and fluxes around three times larger are required to reach the sensitivity to theta_{13} and CP violation for the smallest values of sin^2 2theta_{13} that the standard setup provides. We also studied the required suppression factor of the atmospheric background. In all the setups studied, we found that a suppression factor of 10^-4 is equivalent to removing completely the atmospheric background. Suppression factors of order 10^-3 do not imply a significant loss in sensitivity while suppressions of 10^-2 still allow good CP discovery potential if sin^2 2theta_{13} > 10^-2 and the flux is not too low.