Abe, K. and Adam, J. and Aihara, H. and Akiri, T. and Andreopoulos, C. and Aoki, S. and Ariga, A. and Ariga, T. and Assylbekov, S. and Autiero, D. and Barbi, M. and Barker, G. J. and Barr, G. and Bass, M. and Batkiewicz, M. and Bay, F. and Bentham, S. W. and Berardi, V. and Berger, B. E. and Berkman, S. and Bertram, I. and Bhadra, S. and Blaszczyk, F. d M. and Blondel, A. and Bojechko, C. and Bordoni, S. and Boyd, S. B. and Brailsford, Dominic and Bravar, A. and Bronner, C. and Buchanan, N. and Calland, R. G. and Caravaca Rodriguez, J. and Cartwright, S. L. and Castillo, R. and Catanesi, M. G. and Cervera, A. and Cherdack, D. and Christodoulou, G. and Clifton, A. and Coleman, J. and Dealtry, Thomas and Finch, A. J. and Grant, N. and Kormos, L. L. and Lamont, I. and O'Keeffe, H. M. and Ratoff, P. N. and Reeves, M. and Southwell, L. (2014) Measurement of the intrinsic electron neutrino component in the T2K neutrino beam with the ND280 detector. Physical Review D, 89 (9): 092003. ISSN 1550-7998
Abstract
The T2K experiment has reported the first observation of the appearance of electron neutrinos in a muon neutrino beam. The main and irreducible background to the appearance signal comes from the presence in the neutrino beam of a small intrinsic component of electron neutrinos originating from muon and kaon decays. In T2K, this component is expected to represent 1.2% of the total neutrino flux. A measurement of this component using the near detector (ND280), located 280 m from the target, is presented. The charged current interactions of electron neutrinos are selected by combining the particle identification capabilities of both the time projection chambers and electromagnetic calorimeters of ND280. The measured ratio between the observed electron neutrino beam component and the prediction is 1.01 +/- 0.10 providing a direct confirmation of the neutrino fluxes and neutrino cross section modeling used for T2K neutrino oscillation analyses. Electron neutrinos coming from muons and kaons decay are also separately measured, resulting in a ratio with respect to the prediction of 0.68 +/- 0.30 and 1.10 +/- 0.14, respectively.