We show that Σ+ hyperons produced by 800 GeV/c protons on targets of Be and Cu have significant polarizations (15–20%). These polarizations persist at values of pt≈2 GeV/c and a wide range of xF. The polarizations from the Cu target are consistently less than from Be. The average ratio of the Σ+ polarization from Cu to that from Be is 0.68±0.08.
Measured values of the SIGMA+ polarization as functions of PT and XL for proton CU collisions.
Measured values of the SIGMA+ polarization as functions of PT and XL for proton BE collisions.
We report results of the first measurements of Lambda and Antilambda polarization produced in deep inelastic polarized muon scattering on the nucleon. The results are consistent with an expected trend towards positive polarization with increasing x_F. The polarizations of Lambda and Antilambda appear to have opposite signs. A large negative polarization for Lambda at low positive x_F is observed and is not explained by existing models.A possible interpretation is presented.
The measured and corrected (undiluted) polarizations.
The measured and corrected (undiluted) polarizations.
The diffractive production of ρ0(770 @#@) mesons in muon-proton interactions is studied in the kinematic region 0.15 GeV2< Q2< 20 GeV2 and 20 GeV < ? < 420 GeV. The data were obtained in the Fermilab fixed-target experiment E665 with primary muons of 470 GeV energy. Results are presented on the Q2, x and ? dependence of the cross section, on the shape of the ρ+ρt - mass spectrum, on the slope of the diffraction peak and on the production and decay angular distributions of the ρ0(770). The cross section for diffractive production of ρ0 by virtual photons on protons depends mainly on Q2. At fixed Q2, no significant dependence on x or ? is observed. The extrapolation to Q2 = 0 yields a photoproduction cross section of (10.30 ± 0.33) μb. The slope of the t′ distribution has a value of (7.0 ± 0.2) GeV−2, with a tendency to decrease as Q2 increases. The production and decay angular distributions of the ρ0 depend strongly on Q2 and are consistent with s-channel helicity conservation. The ratio R = σl/σt deduced from the decay angular distributions rises strongly with Q2, passing the value of 1 at Q2≈ 2 GeV2.
Statistical errors only.
Statistical errors only.
Cross section extrapolated to Q**2 = 0.
We report measurements of spin correlations and analyzing powers in He→3(p→, 2p) and He→3(p→, pn) quasielastic scattering as a function of momentum transfer and missing momentum at 197 MeV using a polarized internal target at the Indiana University Cyclotron Facility Cooler Ring. At sufficiently high momentum transfer we find He→3(p→, pn) spin observables are in good agreement with free p−n scattering observables, and therefore that He→3 can serve as a good polarized neutron target. The extracted polarizations of nucleons in He→3 at low missing momentum are consistent with Faddeev calculations.
QUASIELASTIC SCATTERING.
We utilize the angle and momentum resolution of our apparatus to study the polarization of 375 GeV/c Σ+ hyperons produced by 800 GeV/c protons incident on a Cu target. By examining in detail two of our high statistics data samples, we find evidence for structure in the pt dependence of Σ+ polarization and are able to extract the xF dependence of the Σ+ polarization and compare it with xF behavior in the Λ0 and Ξ− systems.
0.9 mrad horizontal sample.
2.9 mrad horizontal sample.
3.3 mrad horizontal sample.
We have mesured the polarization of 375-GeV/c Σ+ and Σ¯ − hyperons produced by 800-GeV/c protons incident on a Cu target. We find that the Σ+ polarization rises with increasing pt to a maximum of 16% at pt=1.0 GeV/c and then decreases to 10% at pt=1.8 GeV/c. We compare this Σ+ polarization with data at lower energies. The Σ¯ − polarization has been measured for the first time. It has the same sign as the Σ+ but smaller magnitude in a similar kinematical region.
Data from Horizontal targeting.
Data from Vertical targeting.
Data from Horizontal targeting.
We have measured the production polarization and magnetic moment of a sample of 89×103Ξ− hyperons produced in the inclusive reaction p(400 GeV/c)+Cu→Ξ−+X. The weighted average of the polarization is -0.070±0.008±0.010 at a pt of 0.63 GeV/c. The Ξ−'s magnetic moment yields the value μΞ=−0.661±0.036±0.036 nuclear magnetons. The first error is statistical, the second systematic.
No description provided.
We have measured the production polarization of 265- and 310-GeV/c Σ− in the inclusive reaction p+Cu→Σ−+X using 400-GeV/c protons. The polarization was analyzed via the asymmetry in the weak decay Σ−→n+π−, and has typical values of +0.20 with respect to the direction of the cross product of the incident-proton and Σ− momenta. Using the spin-precession technique, we have determined the Σ− magnetic moment to be -1.23±0.03±0.03 nuclear magnetons, where the statistical and systematic errors are shown separately.
No description provided.
No description provided.
No description provided.
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