Measurement of sin/sup 2/theta/sub w/ in semileptonic nu Fe and anti nu Fe interactions

We report results from neutral current scattering of muon neutrinos and antineutrinos on iron nuclei by the CCFRR experiment at Fermilab. Our objective is the measurement of sin/sup 2/theta/sub w/ from inclusive semileptonic neutrino-nucleon interactions. Such a measurement, even though it is subject to more corrections than the analogous measurement in neutrino-electron scattering (e.g. due to the presence of a strange quark sea in the nucleon), has a high degree of statistical accuracy and may afford the most precise test of the standard model of electro-weak interactions. Furthermore, the recent observations of the Z/sup 0/ and W/sup +-/ in proton-antiproton collisions give such a measurement added topical interest. The comparison of sin/sup 2/theta/sub w/ determined from the masses of the Z/sup 0/ and W/sup +-/ and from neutrino interactions, i.e. from different processes and energy regions, may hold some surprises. Finally, the grand-unified theories make definite predictions about the value of sin/sup 2/theta/sub w/ and the lifetime of the proton; sin/sup 2/theta/sub w/ measurements test the validity of these theories. The experiment was performed in Fermilab's dichromatic neutrino beam and utilized a large detector consisting of an iron-scintillator target calorimeter followed by a steel toroidal muon spectrometer.