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 and 8Li source ions with a boost factor γ of 650 for the magic baseline while for the closer detector we consider 18Ne and 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 × 10 18 ) and 5 × ( 2.9 × 10 18 ) useful ion decays in neutrino and antineutrino modes respectively, we find that the two-detector set-up can probe maximal CP violation and establish the neutrino mass ordering if sin 2 2 θ 13 is 1.4 × 10 −4 and 2.7 × 10 −4 , respectively, or more. The sensitivity reach for sin 2 2 θ 13 itself is 5.5 × 10 −4 . With a factor of 10 higher luminosity, the corresponding sin 2 2 θ 13 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 δ CP values for sin 2 2 θ 13 ⩾ 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.