Exceptional Sensitivity to Neutrino Parameters with a Two Baseline Beta-Beam Set-up

TL;DR

This paper proposes a two-baseline Beta-beam experiment with carefully chosen detectors and ion sources at CERN to achieve high sensitivity in measuring neutrino mass parameters, including CP violation and mass ordering.

Contribution

It introduces a novel two-baseline setup with optimized ion sources and boosts, demonstrating exceptional sensitivity to neutrino parameters beyond previous configurations.

Findings

Can probe maximal CP violation and neutrino mass ordering at very small 3.

Achieves sensitivity to 3 down to 5.5  with standard luminosity.

Enhanced luminosity improves 3 reach to 1.8  and CP violation discovery for a large 3 range.

Abstract

We examine the reach of a Beta-beam experiment with two detectors at carefully chosen baselines for exploring neutrino mass parameters. Locating the source at CERN, the two detectors and baselines are: (a) a 50 kton iron calorimeter (ICAL) at a baseline of around 7150 km which is roughly the magic baseline, e.g., ICAL@INO, and (b) a 50 kton Totally Active Scintillator Detector at a distance of 730 km, e.g., at Gran Sasso. We choose 8B/8Li source ions with a boost factor \gamma of 650 for the magic baseline while for the closer detector we consider 18Ne/6He ions with a range of Lorentz boosts. We find that the locations of the two detectors complement each other leading to an exceptional high sensitivity. With \gamma=650 for 8B/8Li and \gamma=575 for 18Ne/6He and total luminosity corresponding to 5\times (1.1 \times 10^{18}) and 5\times (2.9\times 10^{18}) useful ion decays in neutrino and antineutrino modes respectively, we find that our two detector set-up can probe maximal CP violation and establish the neutrino mass ordering if \sin^22\theta_{13} is 1.4\times 10^{-4} and 2.7\times 10^{-4}, respectively, or more. The sensitivity reach for \sin^22\theta_{13} itself is 5.5 \times 10^{-4}. With a factor of 10 higher luminosity, the corresponding \sin^22\theta_{13} reach of this set-up would be 1.8\times 10^{-5}, 4.6\times 10^{-5} and 5.3\times 10^{-5} respectively for the above three performance indicators. CP violation can be discovered for 64% of the possible \delta_{CP} values for \sin^22\theta_{13} \geq 10^{-3} (\geq 8\times 10^{-5}), for the standard luminosity (10 times enhanced luminosity). Comparable physics performance can be achieved in a set-up where data from CERN to INO@ICAL is combined with that from CERN to the Boulby mine in United Kingdom, a baseline of 1050 km.