Spin correlation and analyzing power measurements for neutron-proton radiative capture at Tn=183 MeV

We have measured the spin correlation coefficient and the neutron and proton analyzing powers for neutron-proton radiative capture at a neutron beam energy of 183 MeV. Calculations of the spin correlation are particularly sensitive to the treatment of mesonic and isobaric currents. Predictions that include both explicit photon couplings to exchanged mesons and intermediate isobar states, and relativistic correction terms in the Hamiltonian, agree well with our data, thus demonstrating the quantitative accuracy of present treatments of meson-exchange currents at moderate momentum transfer. (Author (revised))