The primary objective of this experiment was to measure normalized cross sections for the interaction νN → μ-X at energies up to Eν = 260 GEV.
The Fermilab dichromatic neutrino beam is made by focusing 400 GEV protons onto a BeO target to produce a secondary beam containing pions and kaons. Pions and kaons decay into neutrinos in a 340m evacuated decay pipe. The absolute π and K flux was determined by measuring the total flux of secondary particles with an ionization chamber and by measuring relative particle composition with a Cherenkov counter. The decay of pions and kaons into neutrinos was calculated to obtain the normalized ν flux at the detector.
We observed 6500 charged current interactions in an 1100 ton iron ν target. Hadron energy deposited in the detector was measured with calorimetric techniques. Muon trajectories were measured with spark chambers. Muon momenta were measured with an iron toroidal magnet.
The total charged current cross section was measured to be σ/Eν = (.700 ±. 038) x 10-38 cm2/GEV independent of energy from Eν = 25 GEV to Eν = 260 GEV. This sets a lower bound on the mass of the W boson of MW > 27 GEV at the 90% confidence level. The mean inelasticity is < y > = .484 ± .012 independent of energy. The antiquark fraction of the nucleon is α = .21 ± .07 at a mean neutrino energy of Eν = 226 GEV. The x distributions were measured in the region .1 < y < .4 at Eν = 67 GEV and at Eν = 226 GEV. Scaling violations were found at low x, but they can be removed by using the scaling variable x' = x/(1 + M2N/Q2).
These results are in good agreement with a simple quark-parton model of deep inelastic scattering.
