We have made measurements of polarization in π−p elastic scattering, with emphasis over the backward region, at 1.60 to 2.28 GeVc. The results indicate the absence of u-channel dominance in the backward region, as was observed in the case of π+p scattering. Comparisons have been made with predictions of various phase-shift analyses which show that the agreement is generally very poor in the backward region.
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The asymmetry in the scattering of π− mesons by polarized protons has been measured at 50 different momenta from 0.643 to 2.14 GeV/c. Results were obtained at values of cosθ ranging from approximately +0.9 to -0.95 in the c.m. system at each incident pion momentum. The pion beam was incident on a 7.6-cm-long crystal assembly of lanthanum magnesium nitrate, in which the hydrogen in the water of crystallization was polarized by the "solid effect." The total momentum spread of the beam was 10% (full width at half-height) and data were collected simultaneously in 4 momentum channels, each with 2½% full width at half-height. A gas Čherenkov counter was used to reject incoming electrons. Scattered particles were detected in scintillation counter arrays placed within the 10-cm gap of the polarized target magnet. Encoded information from each array was stored in the memory of a PDP-5 computer connected on-line to a fast electronic logic network. The computer was programmed to classify the events according to momentum and scattering angle and subdivide them into coplanar and noncoplanar categories. The latter provided a measure of the background. The results have been expressed in the form of an expansion in terms of first associated Legendre polynomial series and compared with the predictions of recent phase-shift solutions. It is concluded that although these analyses give satisfactory predictions of the general features of the results, no one solution gives complete agreement with the data above about 1.0 GeV/c.
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The parameters D, R, R' and P for pp elastic scattering have been measured in the centre-of-mass angular range 13 degrees to 58 degrees with an accuracy of about +or-0.02 at 209, 324, 379, 425 and 515 MeV. These results are incorporated with earlier data into a phase-shift analysis. Phase-shifts are generally in agreement with the theoretical predictions of the Paris group, although the F-wave spin-orbit combination is rather stronger than predicted. The fitted value for the pi 0pp coupling constant in g02=14.06+or-0.65.
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Cross-section values for Compton scattering on the proton were measured at 25 kinematic settings over the range s = 5-11 and -t = 2-7 GeV2 with statistical accuracy of a few percent. The scaling power for the s-dependence of the cross section at fixed center of mass angle was found to be 8.0 +/ 0.2, strongly inconsistent with the prediction of perturbative QCD. The observed cross-section values are in fair agreement with the calculations using the handbag mechanism, in which the external photons couple to a single quark.
Cross section of proton Compton Scattering at centre of mass energy squared of 4.82 GeV.
Cross section of proton Compton Scattering at centre of mass energy squared of 6.79 GeV.
Cross section of proton Compton Scattering at centre of mass energy squared of 8.90 GeV.
The spin correlation parameters$A_{oonn}, A_{ooss}, A_{oosk}, A_{ookk}$and the analyzing power$A_{oono}$have been measured i
Values of the coefficients for the linear combinations of the spin correlation parameters Cpq measurements for the four different beam and target polarisation orientations. For the (z,z) and (y,y) configurations the coefficients are identical for all incident kinetic energies.
Measurement of the analysing power. Statistical errors only are shown. For the systematic errors see the systematics section above. Note that there are two overlapping angular settings.
Measurements of the spin correlation parameter CNN. Statistical errors onlyare shown. For the systematics see the systematic section above. Note the two overlapping angular settings.
A double scattering experiment, performed at the Paul-Scherrer-Institut (PSI), has measured a large variety of spin observables for free np elastic scattering from 260 to 535 MeV in the c.m. angle ran
Relative uncertainties on the carbon polarimeter analysing power (AC).
Relative uncertainty in the beam polarisation (PB).
Measurements of DNN with statistical errors only.
The absolute differential cross section for proton-proton elastic scattering has been measured at 90° c.m. for 300, 350, 400, 450 and 500 MeV. The statistical uncertainty of the measurements is 0.5% with an additional systematic normalization uncertainty of 1.8%. The results are compared to phase-shift analyses.
The statistical and systematic errors are added in quadrature.
We report measurements of the proton form factors GEp and GMp extracted from elastic scattering in the range 1≤Q2≤3 (GeV/c)2 with total uncertainties < 15% in GEp and < 3% in GMp. Comparisons are made to theoretical models, including those based on perturbative QCD, vector-meson dominance, QCD sum rules, and diquark constituents in the proton. The results for GEp are somewhat larger than indicated by most theoretical parametrizations, and the ratios of the Pauli and Dirac form factors Q2(F2pF1p) are lower in value and demonstrate a weaker Q2 dependence than those predictions. A global extraction of the elastic form factors from several experiments in the range 0.1 0.1<Q2<10 (GeV/c)2 is also presented.
Point-to-point systematic uncertainty is 0.5%, overall normailzation uncertainty is 1.9%.
Point-to-point systematic uncertainty is 0.5%, overall normailzation uncertainty is 1.9%.
Point-to-point systematic uncertainty is 0.5%, overall normailzation uncertainty is 1.9%.
Final results for total cross section differences Δσ T and Δσ L measured with a polarized neutron beam transmitted through a polarized proton target are presented. Measurements were carried out at SATURNE II, at 11 energies between 0.63 and 1.1 GeV for Δσ T and at 9 energies between 0.312 and 1.1 GeV for Δσ L . The results are compared with measurements at PSI and LAMPF as well as with Δσ L data points deduced from p-d and p-p transmission experiments at the ANL-ZGS. The present results together with the corresponding pp data allow to determine two of the three imaginary parts of forward scattering amplitudes for isospin I = 0.
Measurements of the tranverse cross section differences.
Measurements of the tranverse cross section differences.
Measurement of the longitudinal cross section difference.
The depolarization parameter D onon in p p elastic scattering has been measured at LEAR for thirteen momenta between 679 and 1550 MeV/c in the backward angular region. Striking disagreement with theoretical models is observed.
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