Pion energy spectra from the reactions np~nn~+ and np~pp~were measured as a function of the angle at 790 MeV. The angular distribution in the np center-of-momentum system was given by [(123.1+2.7)+(88.3+4.9) cps ()~] pb/sr. The total cross section for each reaction was found to be 1.92+0.20 mb. Evidence for T=0 pion production was observed in shape differences between the positive-and negative-pion spectra. However, it was shown that pions are preferentially produced by nucleons in a o'(T =0)=3crptCoulomb effects, the neutron-proton mass difference, and the m. -~+ -mass difference introduce uncertainties in these relationships. However, the corrections to these relationships are estimated to be no more than a few percent. 'The Mandelstam model has been used to describe single-pion production from threshold to about 800 MeV. One of the basic assumptions of this model is that the outgoing pion and one of the nucleons form the b, (1232) resonant state. In this case, isospin conservation requires that the colliding nucleons be in a T =1 state, which means that the total pion-production amplitudes should be front-back symmetic in the center-of-momentum system (c.m.s.) and that cr(T =0) should be zero.However, results from previous experiments concerning reactions (1) and (2) indicate the existence of T =0 amplitudes. Specifically, Yodh found substantial differences between the~+ and energy spectra and angular distributions at 400MeV, a strong indication of interfering T =0 and T =1 amplitudes. Handler also found differences between the pion angular distributions near 400 24 1736

The deuteron sepctra from {n,d) reactions at 800 MeV near 0' are characterized by a high energy quasielastic scattering peak, and at lower momentum, a quasifree scattering peak. The ratio of the quasifree to quasielastic cross sections is approximately 10:1.Both cross sections exhibit an A '" mass dependence over the range of target nuclei studied. Comparisons are made with corresponding proton-induced quasielastic and quasifree deuteron production.NUCLEAR REACTIONS n+ X-d'. E&~= 800 MeV. Measured deuteron quasiekastic and'quasifree cross sections near 0'.The interaction of high-energy protons with nuclei leads to a copious production of high-energy deuterons at angles near 0, both with and without pion production. ' The deuteron spectra near 0 are characterized by a high-energy peak centered at approximately the momentum expected for free Pd-dP elastic scattering, and a second much more intense peak at about the momentum expected for two-body pN-dm pion production processes. 'These two peaks are respectively attributed to guasielastic (QE) and guasifree (QF) scattering in the target nuclei. The present work is concerned with neutron-induced deuteron production.Most

The differential cross section for n-p elastic scattering at 801.

The proton spectrum resulting from 794-MeV neutron bombardment, of deuterium was measured at several angles. The angular distribution of the integral of the quasielastic charge exchange peak is fitted very well by the two exponential form do/dt =n~e8~+ e2e~2' as has previously been found for the np elastic case.

The cross section for elastic scattering of 794-MeV neutrons by deuterium has been measured for neutron center of mass angles from 139' to 179'. The angular distribution is fitted very well both by an empirical function ae"'" "i«' and by a calculation that uses the one parameter Craigie