MEASUREMENT OF THE ELASTIC-SCATTERING OF NEUTRINOS AND ANTINEUTRINOS BY PROTONS

We have observed 217 (66) events of the process νp→νp (ν̄p→ν̄p) with an estimated background of 82 (28). The neutral-to-charged-current ratios are σ(νp→νp) σ(νn→μ-p)=0.11±0.02 and σ(ν̄p→ν ̄p)σ(ν̄p→μ+n)=0.19±0.05 for 0.40<Q2<0.90 (GeV/c)2, where -Q2 is the square of the momentum transfer to the nucleon. These yield σ(ν̄p→ν̄p)σ(νp→νp)=0. 53±0.17. The neutral-current form factors at Q2=0 are GE=0.5-0.5+0.25, GM=1.0-0.04+0.35, and gA=0.5-0.15+0.2. © 1979 The American Physical Society.