Eur. Phys. J. C (2013) 73: 2599
https://doi.org/10.1140/epjc/s10052-013-2599-z

Letter

Search for anomalies in the ν _e appearance from a ν _μ beam

¹ Laboratori Nazionali del Gran Sasso, INFN, Assergi, Italy
² Dipartimento di Fisica e Astronomia, Università di Padova and INFN, Padova, Italy
³ Dipartimento di Fisica, Università di Pavia and INFN, Pavia, Italy
⁴ Politecnico di Milano and INFN, Milano, Italy
⁵ H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Science, Kraków, Poland
⁶ Department of Physics and Astronomy, UCLA, Los Angeles, USA
⁷ Dipartimento di Scienze Fisiche, Università Federico II di Napoli and INFN, Napoli, Italy
⁸ INR RAS, Moscow, Russia
⁹ CERN, Geneva, Switzerland
¹⁰ National Centre for Nuclear Research, Otwock/Swierk, Poland
¹¹ Institute of Physics, University of Silesia, Katowice, Poland
¹² INFN Laboratori Nazionali di Frascati, Frascati, Italy
¹³ GSSI, L’Aquila, Italy
¹⁴ Institute for Radioelectronics, Warsaw University of Technology, Warsaw, Poland
¹⁵ INFN, Pisa, Italy

^* e-mail: daniele.gibin@pd.infn.it

Received: 6 August 2013
Revised: 16 September 2013
Published online: 17 October 2013

Abstract

We report an updated result from the ICARUS experiment on the search for ν _μ →ν _e anomalies with the CNGS beam, produced at CERN with an average energy of 20 GeV and traveling 730 km to the Gran Sasso Laboratory. The present analysis is based on a total sample of 1995 events of CNGS neutrino interactions, which corresponds to an almost doubled sample with respect to the previously published result. Four clear ν _e events have been visually identified over the full sample, compared with an expectation of 6.4±0.9 events from conventional sources. The result is compatible with the absence of additional anomalous contributions. At 90 % and 99 % confidence levels, the limits to possible oscillated events are 3.7 and 8.3 respectively. The corresponding limit to oscillation probability becomes consequently 3.4×10⁻³ and 7.6×10⁻³, respectively. The present result confirms, with an improved sensitivity, the early result already published by the ICARUS Collaboration.