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

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 $\text{nue}$ and/or $\text{anue}$ 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 ${\sin }^{2}2{\theta }_{13}(\mathrm{true})>5.6\times 10^{-4}$ and we can expect an unambiguous signal for ${\theta }_{13}$ at $3\sigma$ C.L. if ${\sin }^{2}2{\theta }_{13}(\mathrm{true})>5.1\times 10^{-4}$ independent of the true neutrino mass hierarchy.

Comments: 26 pages, 20 eps figures, version to appear in Nucl.Phys.B