Measurement of the neutrino velocity with the ICARUS detector at the CNGS beam

TL;DR

This study measures neutrino velocity using the ICARUS detector with a precisely timed, tightly bunched beam, finding neutrinos arrive at the speed of light, contradicting earlier OPERA results suggesting superluminal speeds.

Contribution

It provides a high-precision time-of-flight measurement of neutrinos with a novel beam structure, challenging previous claims of superluminal neutrino speeds.

Findings

Neutrinos arrive consistent with the speed of light.

The measurement contradicts earlier OPERA superluminal neutrino claims.

The experiment demonstrates the effectiveness of tightly bunched beam structures for timing accuracy.

Abstract

The CERN-SPS accelerator has been briefly operated in a new, lower intensity neutrino mode with ~10^12 p.o.t. /pulse and with a beam structure made of four LHC-like extractions, each with a narrow width of 3 ns, separated by 524 ns. This very tightly bunched beam structure represents a substantial progress with respect to the ordinary operation of the CNGS beam, since it allows a very accurate time-of-flight measurement of neutrinos from CERN to LNGS on an event-to-event basis. The ICARUS T600 detector has collected 7 beam-associated events, consistent with the CNGS delivered neutrino flux of 2.2 10^16 p.o.t. and in agreement with the well known characteristics of neutrino events in the LAr-TPC. The time of flight difference between the speed of light and the arriving neutrino LAr-TPC events has been analysed. The result is compatible with the simultaneous arrival of all events with equal speed, the one of light. This is in a striking difference with the reported result of OPERA that claimed that high energy neutrinos from CERN should arrive at LNGS about 60 ns earlier than expected from luminal speed.