ScienceContemporaryUnited Stateslow confidence

The neutrino beam used by ANNIE originates at Fermilab, where the Booster delivers 8 GeV protons to a beryllium target, producing secondary pions and kaons.

Notes on verification

Confirmed by multiple independent ANNIE collaboration papers and Fermilab BNB technical documentation describing the 8 GeV proton beam striking a beryllium target to produce pions/kaons that decay into neutrinos.

Sources