Direct measurements were made of neutron-proton elastic scattering differential cross sections a t high energies. X neutron beam with a continuous momentum spectrum between 1.2 and 6.7 GeV/c was scattered off a liquid hydrogen target, and spark chambers were used to determine the neutron scattering angle and, in a proton spectrometer, to measure the momentum and scattering angle of the recoil proton. Differential cross sections are presented over the incident neutron momentum range in intervals of the order of 0.5-GeV/c wide. The cross sections have an exponential peak in the forward direction and then flatten and become isotropic about the 90' c.m. scattering angle. At larger angles, the cross sections again rise towards the expected charge-exchange peak, which was not within the range of this experiment. There is little evidence of any other structure in the cross section. Values are presented for the slope of the diffraction peak, and comparisons are made between these slopes, and the 90" c.m. cross sections, for p p and n p elastic scattering. The results presented here differ from those previously reported because of an error in a Monte Carlo calculation and in the availability of improved data on the real part of the n p elastic scattering amplitude. At 5 GeV/c, a direct comparison of p p and n p data allows the I = 0 differential cross section to be extracted.The n p data have been fitted in powers of cosfl, , . for Icosfl,, / <0.8 for each energy range

It ha~ been shown previo~sly by Newton that his solution (and its extension by Sabatier) of the problem of find~ng a cent:al potentIal from a knowledge of all phase shifts at fixed energy yields a series whose expansl~n coefficlen~s converge slowly unless the first moment of the potential vanishes. In particular, any truncatIOn of the serl~s after a finite number of terms necessarily results in potentials which have vanishing firs.t moments. In thIS ~aper we propose a new, but formally somewhat similar, series for the potential WhICh, for such truncatIons, does not suffer from this physically rather severe restriction. The series also furnishes ~ew exact. solut~ons Of. the SchrOding~r equation at fixed energy. A closed-form expression for the scattermg amplItude IS obtamed for a specIfic example. The problem of constructing the "new series from the phase shifts is not discussed.

A generalization of the Bargmann potentials to include the case of nonrelativistics-wave scattering of a particle by a target having a finite number of discrete excited states is presented. This generalization allows the explicit construction of a large class of many-channel S-matrices meromorphic on their energy Riemann surfaces as well as the explicit construction of the corresponding potential matrices. A two-channel example is treated in detail.