Exceptional Sensitivity to Neutrino Parameters with a Two Baseline Beta-Beam Set-up
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 γ 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 γ=650 for 8B/8Li and γ=575 for 18Ne/6He and total luminosity corresponding to 5× (1.1 × 1018) and 5× (2.9× 1018) 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 22θ13 is 1.4× 10-4 and 2.7× 10-4, respectively, or more. The sensitivity reach for 22θ13 itself is 5.5 × 10-4. With a factor of 10 higher luminosity, the corresponding 22θ13 reach of this set-up would be 1.8× 10-5, 4.6× 10-5 and 5.3× 10-5 respectively for the above three performance indicators. CP violation can be discovered for 64% of the possible δCP values for 22θ13 ≥ 10-3 (≥ 8× 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.