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DATA AVERAGED FOR TWO DIRECTIONS OF TARGET POLARIZATION.
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The depolarization parameter for pp inclusive scattering at an incident momentum of 6 GeV/c was measured. The D parameter for inclusive scattering indicates the dominance of natural-parity exchange at small t, except in the case of N*(1232) production, where π exchange is more important. D for elastic scattering has also been measured. This parameter shows a small decrease from unity with increasing momentum transfer.
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Measurement was made of dσdt for n↑+p↑→n+p at P⊥2=0.8 and 1.0 (GeV/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−p elastic scattering which are quite different from the p−p spin-spin effects.
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Measurements have been made of the double polarisation parameters G and H in the photoproduction of neutral pions from protons, for incident photon energies between 1300 MeV and 2300 MeV and for pion c.m. angles between 50δ and 80δ. The results are compared with predictions from a recent comprehensive analysis of earlier photoproduction data.
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Toward the goal of experimentally determining pp elastic scattering amplitudes at 6 GeV/c, we have measured a linear combination of triple-spin correlation parameters and also a linear combination of spintransfer parameters over the |t| range between 0.2 and 1.0 (GeV/c)2. A horizontally polarized beam (S direction) was obtained by precessing the spin of the polarized beam from the Argonne Zero Gradient Synchrotron using a superconducting solenoid. The target protons were polarized vertically (N direction) and the polarization of the recoil protons was measured with a carbon polarimeter. The results are consistent with the amplitude corresponding to π exchange being almost real and positive.
KSS = (S00S) AND HSNS = (SN0S) MEASURED HERE CONTAIN SMALL ADMIXTURES OF THE OTHER SPIN-TRANSFER AND TRIPLE-SPIN CORRELATION PARAMETERS RESPECTIVELY DUE TO THE POLARIZED TARGET MAGNETIC FIELD - SEE TEXT. MEAN VALUE OF HSNS OVER THIS T-RANGE IS 0.098 +- 0.085. PARITY CONSERVATION REQUIRES THE VANISHING OF THE PARAMETERS KSN, HSNN, (000S) AND DNS, WHILE (000N) MUST AGREE WITH THE SINGLE SCATTERING POLARIZATION PARAMETER (0N00).
We measured dσdt for p↑+p↑→p+p from P⊥2=4.50 to 5.09 (GeV/c)2 at 11.75 GeV/c. We used a 59%-polarized proton beam and a 71%-polarized proton target with both spins oriented perpendicular to the scattering plane. In these large-P⊥2 hard-scattering events, spin effects are very large and the ratio (dσdt)↑↑:(dσdt)↑↓ grows rapidly with increasing P⊥2, reaching a value of 4 at 90° (c.m.). Thus, hard elastic scattering, which is presumably due to the direct scattering of the protons' constituents, may only occur when the two incident protons' spins are parallel.
THE ERRORS INCLUDE STATISTICAL AND SYSTEMATIC ERRORS ADDED IN QUADRATURE. THE PARALLEL/ANTIPARALLEL SPIN CROSS SECTION RATIO IS (1+CNN)/(1-CNN).
We have measured the spin-spin correlation parameter CLL=(L, L;0, 0) in p−p elastic scattering around θc.m.=90° from plab=1.0 to 3.0 GeV/c. We observe a rapid energy dependence in CLL and describe our interpretation of the results.
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We measured d σ d t(90° cm ) for ↑+ p ↑→ p + p from 1.75 to 5.5 GeV/ c , using the Argonne zero-gradient synchrotron 70% polarized proton beam and a 70% polarized proton target. We found that the spin-spin correlation parameter. A nn , equals 60% at low energy, then drops sharply to about 10% near 3.5 GeV/ c , and remains constant up to 5.5 GeV/ c .
ANALYZING POWER. QUOTED ERRORS DUE TO 4.3 PCT POINT TO POINT RELATIVE ERROR.
THE SPIN-SPIN CORRELATION PARAMETER CNN IS NOW DENOTED BY ANN ACCORDING TO THE NEW ANN ARBOR CONVENTION.
The pp total cross section difference between pure transverse spin states was measured in the laboratory momentum range 1–3 GeV/ c . Significant differences were found and these differences show striking energy dependence. This structure is in disagreement with the predictions of simple exchange models.
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REVISED DATA (J. D. LESIKAR, PRIV COMM, 19 JUN 1981). NOW CORRECTED FOR COULOMB-NUCLEAR INTERFERENCE. IN ADDITION, THE LOWEST MOMENTUM DATA POINT IS NOW KNOWN TO BE IN ERROR.
The reaction\(\bar pp \to \bar \Lambda \Lambda \) has been studied in a bubble chamber experiment at eight incident momenta between 1.50 and 2.06 GeV/c. The differential cross-section, the polarization and the spin correlation coefficients have been measured. They have been compared with the prediction of two theoretical models: the K-meson conspiracy and the exchange of the K*K** degenerate trajectory associated with a Regge cut. The latter model gives the best representation of the data.
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POLARIZATION AND SPIN CORRELATION COEFFICIENTS. AVERAGED OVER ALL ANGLES. SEE PAPER FOR DEFINITIONS, MORE DETAILS AND POSSIBLE T-DEPENDENCE.
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