MEASUREMENT OF THE LONGITUDINAL SPIN-DEPENDENT NEUTRON-PROTON TOTAL CROSS-SECTION DIFFERENCE DELTA-SIGMA-L(NP) BETWEEN 500 AND 800-MEV

A measurement of DELTAsigma(L)(np), the difference between neutron-pro ton total cross sections for pure longitudinal spin states, is describ ed. Data were taken at LAMPF for five neutron beam kinetic energies: 4 84, 568, 634, 720, and 788 MeV. The statistical errors are in the rang e 0.64-1.35 mb. Various sources of systematic effects were investigate d and are described. Overall systematic errors are estimated to be on the order of 0.5 mb and include an estimate for the uncertainty in the neutron beam polarization. The DELTAsigma(L) results are consistent w ith previous results from PSI and Saclay. These data, when combined wi th other results and fitted to a Breit-Wigner curve, are consistent wi th an elastic I=0 resonance with mass 2214 +/- 15 (stat) +/- 6 (syst) MeV and width 75 +/- 21 +/- 12 MeV. Because of a lack of DELTAsigma(T) (np) data between 500 and 800 MeV, it is not possible to differentiate between a singlet or coupled-triplet partial wave being responsible.