Neutrino oscillation studies at INO ICAL
ABSTRACT :
The proposed 50 kTon magnetised Iron Calorimeter (ICAL) detector at India-based Neutrino Observatory (INO) aims to study the effect of Earth matter on the propagation of atmospheric neutrinos and determine neutrino oscillation parameters. The main goal of ICAL is to determine neutrino mass hierarchy and perform precision measurements on the 2-3 mixing angle and mass-squared difference. The ICAL detector is optimised to detect charged current (CC) muon neutriuno and anti-neutrino events. These events have a muon track and hadron shower in the final state. Using a magnetic field, the charge of the muon can be determined and thus neutrino and anti-neutrino events can be identified separately. Muons have excellent energy and direction resolutions in ICAL. The only information about hadrons available in ICAL are the number and position of hits in the shower. Using this the energy and direction of hadrons can be reconstructed. Though have comparitively worse resolutions than muons, adding hadron energy along with muon momentum and direction as one of the final state observables improves the sensitivity to oscillation parameters. Performing the analysis in a wider range of observed muon energy, i.e, 0.5-25 GeV, and also imposing a constraint on the ration of muon-neutrino and anti-neutrino events improves the sensitivity to parameters especially to the 2-3 mixing angle. ICAL being a huge detector can be used to probe exotic phenomena like neutrino decay. Analysis of 500kTon exposure of ICAL with only CC muon-neutrino and anti-neutrino events can constrain the life time of the third mass eigen state, two orders of magnitude tighter than MINOS. If decay is present in nature it will affect the measurement of the standard oscillation parameters also. These are also studied.