Unraveling neutrino parameters with a magical beta-beam experiment at INO

TL;DR

This paper proposes a beta-beam experiment with a large magnetized iron detector at INO, capable of precisely determining neutrino mass hierarchy and mixing angle θ13, with minimal CP phase interference at a 7500 km baseline.

Contribution

It introduces a novel experimental setup using a beta-beam at INO with a long baseline, achieving high sensitivity to neutrino parameters and reducing degeneracies.

Findings

Mass hierarchy can be determined at 3σ if sin^2 2θ13 > 5.6×10^{-4}.

Unambiguous θ13 signal at 3σ if sin^2 2θ13 > 5.1×10^{-4}.

CP phase effects are negligible at this baseline.

Abstract

We expound in detail the physics reach of an experimental set-up in which the proposed large magnetized iron detector at the India-based Neutrino Observatory (INO) would serve as the far detector for a so-called beta-beam. If this pure $\nue$ and/or $\anue$ beam is shot from some source location like CERN such that the source-detector distance $L \simeq 7500$ km, the impact of the CP phase $\delta_{CP}$ on the oscillation probability and associated parameter correlation and degeneracies are almost negligible. This ``magical'' beta-beam experiment would have unprecedented sensitivity to the neutrino mass hierarchy and $\theta_{13}$, two of the missing ingredients needed for our understanding of the neutrino sector. With Lorentz boost $\gamma=650$ and irrespective of the true value of $\delta_{CP}$, the neutrino mass hierarchy could be determined at $3\sigma$ C.L. if $\sin^22\theta_{13}{\rm {(true)}} > 5.6 \times 10^{-4}$ and we can expect an unambiguous signal for $\theta_{13}$ at $3\sigma$ C.L. if $\sin^22\theta_{13}{\rm {(true)}} > 5.1 \times 10^{-4}$ independent of the true neutrino mass hierarchy.