Veto authority over muons

This striking red wall, in combination with scintillator paddles behind it (not seen in the photo), is known as the MINERvA veto wall. Located in the NuMI neutrino beamline 105 meters underground, the veto wall tags muons that come from neutrinos that interact in the rock upstream of the wall. The muons then pass through into the rest of the MINERvA detector (into the plane of the picture). Marking these particles as they enter the detector allows scientists to distinguish between the muons from upstream and those created in the MINERvA detector, behind the wall. The muons (and other particles) arising from the neutrino interactions inside the detector are the ones scientists want to measure to better understand neutrinos themselves. Photo: Ruben Carcagno, TD