We measured the differential cross section for proton-proton elastic scattering at 6 GeV/c, with both initial spins oriented normal to the scattering plane. The analyzing power $A$ shows significant structure with a large broad peak reaching about 24% near ${{P}_{\ensuremath{\perp}}}^{2}=1.6$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$. The spin-spin correlation parameter ${A}_{\mathrm{nn}}$ exhibits more dramatic structure, with a small but very sharp peak rising rapidly to about 13% at 90${\mathrm{\ifmmode^\circ\else\textdegree\fi{}}}_{\mathrm{c}.\mathrm{m}.}$. This sharp peak may be caused by particle-identity effects.

Data are presented on the energy dependence of the spin-spin correlation parameter, Ann, for pp elastic scattering at 90°cm over the beam momentum range 6 to 12. 75 GeV/c. Ann is about 10% up to 8 GeV/c then climbs rapidly to a value of about 60% at 11 GeV/c. Our data indicate that Ann may depend only on the variable P ⊥ 2 and suggests that Ann may reach a limiting value of about 60%.

A collaboration has been formed to create a high energy polarized beam facility at the Brookhaven National Laboratory AGS.1 Argonne National Laboratory, in collaboration with Yale University, will provide the polarized source as part of its contribution. It must produce polarized H- since the AGS is converting to H injection. Intensity is critical because of the short linac pulse (≤ ½ msec). Our design is based on a source recently built by W. Haeberli at the University of Wisconsin.2,3 This is the first source that uses the reaction Cs0+H ↑ 0 →Cs++H ↑ - , and it has excellent intensity (1–3 µAmps DC) and polarization (~90%). Using the improvements described below, the AGS source should produce a much higher intensity (pulsed) and should retain the high polarization of the Wisconsin source. It is scheduled to be operational at BNL by October 1982.

Data from the ANL 12-foot bubble chamber have been used to study the ${\overline{K}}^{0}{\ensuremath{\pi}}^{\ensuremath{-}}$ system in the reaction ${K}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\overline{K}}^{0}p{\ensuremath{\pi}}^{\ensuremath{-}}$ at 6.5 GeV/c. Signals for the production of ${K}^{*}(892)$, ${K}^{*}(1430)$, and ${K}^{*}(1780)$ were observed with cross sections of 181\ifmmode\pm\else\textpm\fi{}22, 41.2\ifmmode\pm\else\textpm\fi{}6, and 8.4\ifmmode\pm\else\textpm\fi{}2.9 \ensuremath{\ge}b, respectively. The partial waves contributing to the production of the ${\overline{K}}^{0}{\ensuremath{\pi}}^{\ensuremath{-}}$ system from threshold up to 1.7 GeV were studied. The principal conclusions are: (i) ${K}^{*}(892)$ and ${K}^{*}(1430)$ production is dominated by natural-parity exchange, (ii) the ratio of unnatural- to natural-parity exchange increases with the resonance mass, consistent with the predictions of a triple-Regge model, (iii) there is evidence for a broad ${0}^{+}$ $s$-wave enhancement, with considerable $s\ensuremath{-}d$ and $s\ensuremath{-}p$ interference, centered at 1.2 GeV, and (iv) the $m=2$ amplitudes are negligible.

Before the shutdown of the Argonne Zero Gradient Synchrotron (ZGS) in October 1979, our group extended our previous measurements1 of the 6 GeV/c P-P elastic scattering rates with beam and target polarizations normal to the scattering plane. The experimental technique has been described in the previous publications, but some improvements were made as shown in Fig. 1. Additional momentum resolution was added in the recoil arm and the solid angle was increased by the use of two element hodo-scopes. Beam intensity was increased by a factor of 3 and additional shielding was installed. Along with the usual statistical uncertainty and errors in measurement of the target polarization, we have added in quadrature a term due to a systematic difference between target and beam asymmetries (AT and AB). Figure 2 shows the results plotted against P ⊥ 2 . This may be an appropriate variable since our recent data2 at 11.75 GeV/c seems to indicate that Ann may depend solely on P ⊥ 2 .

Data are presented for the spin correlation parameter ANN in the inclusive reactions P↑ + P↑ → π+ + X and P↑ + P↑ → P + X at 6 GeV/c. For π+ inclusives substantial asymmetries are observed which decrease with increasing momentum transfer squared P T 2 . For proton inclusives ANN is small but appears to increase with increasing P T 2 .

The final configuration of the Polarized Proton Ion Source used at the Argonne Zero Gradient Synchrotron and the changes to the original configuration are summarized. In particular, we describe the results of cooling the dissociator nozzle to very low temperatures.

The polarized H- ion source that Argonne National Laboratory and Yale University are building for the AGS polarized beam facility is based on the crossed beam concept in which a polarized atomic hydrogen beam, H↑o, is ionized to H- by a fast neutral cesium beam, Cso. We describe our studies which will aid in achieving a high intensity polarized H- beam. In particular, we describe time-of-flight studies on the atomic beam and the effect of dissociation nozzle cooling on the velocity distribution. The cesium gun design is described, and a brief discussion of the H↑o-Cso interaction region is given.

Modifications made on the ZGS to allow the acceleration of polarized deuterons and the operational experiences with the first production run with this beam are described.

Measurement was made of $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ for ${n}_{\ensuremath{\uparrow}}+{p}_{\ensuremath{\uparrow}}\ensuremath{\rightarrow}n+p$ at ${{P}_{\ensuremath{\perp}}}^{2}=0.8 \mathrm{and} 1.0$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ at 6 GeV/c. The 6-GeV/c 53%-polarized neutrons from the 12-GeV/c polarized deuteron beam at the Argonne zero-gradient synchroton were scattered from our 75%-polarized proton target. Both spins were oriented perpendicular to the scattering plane. We found large unexpected spin-spin effects in $n\ensuremath{-}p$ elastic scattering which are quite different from the $p\ensuremath{-}p$ spin-spin effects.