Measurement of neutrino velocity with the MINOS detectors and NuMI neutrino beam

The velocity of a $\sim 3\mathrm{GeV}$ neutrino beam is measured by comparing detection times at the near and far detectors of the MINOS experiment, separated by 734 km. A total of 473 far detector neutrino events was used to measure $(v-c)/c=5.1\pm 2.9\times {10}^{-5}$ (at 68% C.L.). By correlating the measured energies of 258 charged-current neutrino events to their arrival times at the far detector, a limit is imposed on the neutrino mass of $m_{\nu }<50\mathrm{MeV}/c^2$ (99% C.L.).

Figure 1

Neutrino event time distribution measured at the MINOS near detector. The top plot corresponds to events in 5-batch spills $P_1^5(t_1)$ while the bottom plot corresponds to 6-batch spills $P_1^6(t_1)$.

Figure 2

Time distribution of FD events relative to prediction after fitting the time of flight. The top plot shows events in 5-batch spills, the bottom 6-batch spills. The normalized expectation curves $P_2^5(t)$ and $P_2^6(t)$ are shown as the solid lines.

Figure 3

The time and reconstructed energy for contained ${\nu }_{\mu }$ charged-current events. The points show the measured times of events and reconstructed energy $E_{\mathrm{reco}}$. The horizontal error bars indicate the $\sim 1\sigma$ energy uncertainty. The gray filled region indicates the allowed range of times predicted by a neutrino with $m_{\nu }=50\mathrm{MeV}/c^2$. The solid lines indicate the allowed range predicted $m_{\nu }=17\mathrm{MeV}/c^2$.