Search Results (5 total)

The highest-energy measurement of Δσ_L(pp) and the first ever measurement of Δσ_L(p¯p), the differences between proton-proton and antiproton-proton total cross sections for pure longitudinal spin states, are described. Data were taken using 200-GeV/c polarized beams incident on a polarized-proton target. The results are measured to be Δσ_L(pp)=-42 ± 48(stat)± 53(syst) μb and Δσ_L(p¯p)=-256 ± 124(stat)± 109(syst) μb. Many tests of systematic effects were investigated and are described, and a comparison to theoretical predictions is also given. Measurements of parity nonconservation at 200 GeV/c in proton scattering and the first ever of antiproton scattering have also been derived from these data. The values are consistent with zero at the 10^-5 level.

The inclusive vector analyzing power iT₁₁ of π⁺→⁷Li elastic scattering and inelastic scattering to the 0.47 MeV excited state was measured at several angles for T_π=134, 164, and 194 MeV. The polarization effects were found to be small but nonzero, the trend of the data is well described by a coupled channels calculation. The results of the calculation are more sensitive to variations of the nuclear structure input than to variations of the reaction mechanism.

Measurements of 20 vector and tensor spin observables in d-p elastic scattering at a deuteron bombarding energy of 1.6 GeV (800 MeV equivalent proton beam energy) are reported. Of these 10 are two-spin observables and the remaining ten are three-spin observables. The two-spin observables, six of which have been measured for the first time, were measured in the four-momentum-transfer range 0.12 to 0.85 (GeV/c)². The three-spin observables, of which eight were measured for the first time, were measured in the momentum-transfer range 0.2 to 0.85 (GeV/c)². The magnitude of the average vector polarization of the deuteron beam was 0.3, and of the average tensor alignment was 0.85. A frozen spin-polarized proton target was utilized for these measurements. These results are compared with previous measurements when possible, and show a general agreement. They are also compared with the predictions of the relativistic-impulse approximation, and its modified version, which takes into account a nontrivial off-mass-shell behavior of nucleon-nucleon scattering amplitudes.

The vector analyzing power iT₁₁ was measured for π⁺-⁶L→i elastic and inelastic scattering (3⁺, 2.19 MeV) at 100, 134, 164, and 219 MeV, in an angular range between 40° and 125° using a vector polarized ⁶LiD target. Sizable spin effects were observed over most of the angular range. The data were compared with a number of theoretical predictions based on different scattering models and nuclear structure input. None of the calculations is able to reproduce the data set; however, it appears that the vector analyzing power iT₁₁ is mostly sensitive to the nuclear wave function chosen. The angular distribution of iT₁₁ in π⁺-⁶Li elastic and inelastic scattering is discussed in terms of nuclear form factors and elementary πN amplitudes.

We present the first measurements of spin effects in π⁺ elastic and inelastic scattering from complex nuclei, ¹⁵N→((1/2^-) and ⁶Li→(1⁺). For the case of ¹⁵N→, the analyzing power A_y was measured at T_π=164 MeV between 60° and 100°. Although large values of A_y are predicted by theory, the data are consistent with zero. For the case of ⁶Li→, the analyzing power iT₁₁ was measured at T_π=134 and 164 MeV, between 50° and 110°. Large values of iT₁₁ were found at some angles, but the measured angular distributions differ considerably from theoretical predictions.