Neutron-proton elastic scattering spin-spin correlation parameter measurements between 500 and 800 MeV. II.CSSandCLS

Abstract

Results are presented for the spin-spin correlation parameters C,y,y and C,, for free np elastic scattering at neutron beam kinetic energies of 484, 634, 720, and 788 MeV and c.m. angles between 25" and 80". The measurements were performed with a polarized neutron beam and a polarized proton target. These are the first measurements of this type to be reported in the forward angular region with a free polarized neutron beam. The observables Css and CLs are both small at all energies, except for CLs at 788 MeV, which is larger than phase-shift analysis predictions by more than one standard deviation for most of the measured points.

Calculation of Spin Observables for Proton-Neutron Elastic Scattering in the Bethe-Salpeter Equation

“…In the case of av equation the rising of the curve at θ > 130 • is explained by the L=2 component of M 1 ss (θ) giving the term ∼ cos 4θ. The experimental data is seen to be around A xx (θ) ∼ 0.1 [6] extensively and by using the effective value c = 1.2 the result of av is improved as A xx (90 • ) ∼ 0.2.…”

“…The experimental data is from the 484 MeV in ref. [6]. Figure 8: The spin transfer K nn as a function of the center of mass scattering angle θ at the laboratory energy of 500 MeV.…”

Experimental studies of pion-nucleus and nucleon-nucleus interactions at intermediate energies. Progress report, April 1, 1991--March 31, 1994

“…The Newn's polarization effect occurs for all pion angles, but for fixed pion angle it has a very characteristic sign change as the proton angle passes through the free n-p kinematical point. These results may help shed light on the unexpectedly small asymmetries observed in elastic scattering on 15N [17] and 13C, [18] and they may also be sensitive to the strength of the delta-nucleus spin-orbit interaction. The data analysis is underway at Maryland as part of the Ph.D. thesis of Mohammed Khayat.…”

“…The polarized target setup would be essentially the same as we used previously at pion energies above 100 MeV. [18,83,841 Some modifications would be necessary, however, which result from the lower energy of the pions. These include the use of a dilution refrigerator with a thin window rather than a 3He cryostat, to allow running in frozen-spin mode with a low magnetic field around the polarized target, and providing for the rotation of the refrigerator so as to minimize the contribution of the target thickness to the experimental resolution.…”

“…The first measurement of asymmetries of .rr+ elastic scattering from polarized I3C was carried out in 1989 with the Large Acceptance Spectrometer (LAS) at LAMPF. [18] In analyzing the data it became apparent that the acceptance of the LAS at large scattering angles was not sufficiently well known to extract reliable differential cross sections, a problem which did not affect the measurement of the asymmetry. However, for a thorough theoretical analysis of the asymmetry data it is important to have accurate differential cross section data as well.…”