A precise calibration of the SLAC 8 GeV spectrometer using the floating wire technique

The SLAC 8 GeV/c spectrometer was optically calibrated using the floating wire technique. The forward and reconstruction optics coefficients were measured as a function of spectrometer momentum. The point-to-point uncertainty for the large, first-order coefficients was [plus minus]0.4% or better, with an absolute normalization uncertainty of[plus minus]1.0%. These coefficients were used to determine the momentum dependence of the acceptance, and to constrain a newly developed TRANSPORT model of the spectrometer which reproduces the measurements to within their errors. The central momentum, P[sub c], was measured for fourteen nominal set-points to [plus minus]0.025% absolute uncertainty. A linear fit to measured central momenta and corresponding dipole NMR field measurements gives P[sub c] = 0.41511B + 0.00054, where B is the magnetic field of the dipoles in kG, and P[sub c] is in GeV/c.