Measurement of the velocity of neutrinos from the CNGS beam with the Large Volume Detector

TL;DR

This paper reports a precise measurement of neutrino velocity over a 732 km baseline, establishing that neutrinos travel at speeds indistinguishable from light within very tight experimental limits.

Contribution

The study provides the most accurate direct measurement of neutrino velocity to date, significantly reducing the uncertainty compared to previous experiments.

Findings

Neutrino velocity difference from light is within -3.8 x 10^-6 to 3.1 x 10^-6 at 99% confidence level.

48 neutrino events detected with high timing accuracy.

Results improve constraints on neutrino speed compared to prior measurements.

Abstract

We report the measurement of the time-of-flight of ~17 GeV muon neutrinos on the CNGS baseline (732 km) with the Large Volume Detector (LVD) at the Gran Sasso Laboratory. The CERN-SPS accelerator has been operated from May 10th to May 24th 2012, with a tightly bunched-beam structure to allow the velocity of neutrinos to be accurately measured on an event-by-event basis. LVD has detected 48 neutrino events, associated to the beam, with a high absolute time accuracy. These events allow to establish the following limit on the difference between the neutrino speed and the light velocity: -3.8 x 10-6 < (v-c)/c < 3.1 x 10-6 (at 99% C.L.). This value is an order of magnitude lower than previous direct measurements.