The analyzing power A and spin-transfer parameters K NN> K ss , K SL , and K LL have been measured in the np charge-exchange (np~~pn) region at 790 MeV. These data provide new and unique information on the spin dependence of the np interaction in the charge-exchange region. Models which explain the charge-exchange peak in the np elastic differential cross section as being due to interference between one-pion exchange and a slowly varying background are in basic agreement with the data.PACS numbers: 13.75.Cs, 21.30.+y During the past 25 years, a number of measurements have been made of the np differential cross section in the charge-exchange (CEX) region over a large energy range. 1 The differential cross section shows a pronounced peak in this region, which when plotted as a function of four-mo menturn transfer squared, u, has a shape nearly independent of energy from about 200 MeV to beyond 60 GeV. This peak has a width of about 0.02 (GeV/c) 2 , roughly equal to that of the mass of the pion (m-^) squared. The width of the peak strongly suggests that one-pion exchange (OPE) is the dominant mechanism; however, the cross section calculated from OPE is proportional to [u/ (u -m*)T in the first Born approximation. This clearly gives a dip in the CEX region, rather than the observed peak, and also gives cross sections too large outside this region. The predictions of Reggeized OPE 2 are closer in magnitude to the observed cross section than simple OPE, 3 but still give a dip in the cross section at u =0. In 1963 Phillips 4 noted that the peak is consistent with a nearly constant background which interferes destructively with the OPE contribution. The many subsequent attempts to explain the origin of such a background fall into two categories, namely absorption and cut models, both based in Regge theory. Absorption models assume that the pion pole is modified by inelastic channels. Regge-cut models evaluate double exchanges. Chia, 5 for example, models the pion-Pomeron exchange and calculates its contribution to np CEX and other reactions, with some success. A detailed review of the above models and references to the original works are given by Jones. 6 Theoretical understanding of the CEX region has been hampered by a lack of information about the spin dependence of the interaction over the range in u from 0 to about -0.05 (GeV/c) 2 in which the peak is observed. Except for the analyzing power the only available spin-dependent data 7 are very imprecise values for K NN andif ss near 600 MeV. In that experiment an average value for the entire CEX region was obtained, and hence little can be deduced about the mechanism responsible for the peak. We report here new measurements of np spin-dependent observables in the CEX region.The experimental setup is shown in Fig. 1. A 790-MeV polarized neutron beam (P"^0.40) is produced via polarization transfer in the reaction p po id-~n pol pp (]K LL = -0.65 andP^0.7) 8 at 0°, and is collimated to a diameter of about 10 cm at the liquid hydrogen target. Two dipole magnets, M x (vert...