▁comparing ▁oscill ations ▁of ▁neut r inos ▁to ▁those ▁of ▁ant ine ut r inos , ▁as ▁well ▁as ▁more ▁precise ▁measurements ▁of ▁ Δ m ▁and ▁ θ 2 3 ▁parameters , ▁and ▁cross - section ▁measurements ▁which ▁will ▁extend ▁our ▁understanding ▁of ▁neut r ino ▁interactions ▁and ▁thus ▁improve ▁theoretical ▁models ▁used ▁in ▁neut r ino ▁gener ators . ▁ ▁Ne ut r ino ▁beam ▁ ▁T 2 K ▁uses ▁a ▁mu on ▁neut r ino ▁or ▁mu on ▁ant ine ut r ino ▁beam ▁produced ▁at ▁the ▁J - PAR C ▁facility ▁using ▁a ▁pro ton ▁beam ▁gradually ▁acceler ated ▁to ▁ 3 0 ▁Ge V ▁by ▁a ▁system ▁of ▁three ▁acceler ators : ▁first ▁to ▁ 4 0 0 ▁Me V ▁energy ▁by ▁the ▁Lin ac ▁linear ▁acceler ator , ▁then ▁up ▁to ▁ 3 ▁Ge V ▁by ▁the ▁R CS ▁( R ap id ▁Cy cle ▁Syn ch ro tr on ), ▁and ▁finally ▁up ▁to ▁ 3 0 ▁Ge V ▁by ▁the ▁MR ▁syn ch ro tr on ▁( Main ▁Ring ). ▁Pro tons ▁col lide ▁with ▁a ▁graph ite ▁target , ▁producing ▁mes ons , ▁mainly ▁p ions ▁and ▁ka ons , ▁which ▁are ▁then ▁focused ▁by ▁a ▁set ▁of ▁three ▁magnetic ▁horn s ▁and ▁directed ▁into ▁a ▁tunnel ▁called ▁the ▁decay ▁volume . ▁Depending ▁on ▁the ▁horn s ▁polar ity , ▁either ▁positive ▁or ▁negative ▁particles ▁are ▁focused . ▁Pos itive ▁p ions ▁and ▁ka ons ▁decay ▁mainly ▁into ▁ ▁and ▁, ▁forming ▁a ▁mu