Toward the goal of experimentally determining the p-p elastic-scattering amplitudes at 6 GeV/c, we have measured a number of triple- and double-spin correlation parameters over the ‖t‖ range between 0.2 and 1.0 (GeV/c)2. These new data permit the first nucleon-nucleon amplitude determination in the multi-GeV energy range. Polarized beams from the Argonne Zero Gradient Synchrotron and polarized targets were utilized. The polarization of the recoil proton was measured with a carbon polarimeter. A total of 14 different spin observables were measured (five spin transfer, four depolarization, and five triple-spin correlation parameters). These have been combined with earlier results, resulting in a data set of typically 30 measurements of 20 different spin observables for each of six ‖t‖ values between 0.2 and 1.0 (GeV/c)2. A solution for the amplitudes has been found at each ‖t‖, and comparisons are presented with several different models. The spin-nonflip helicity amplitudes are found to be much larger than the spin-flip amplitudes.
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At the Cooler Synchrotron COSY/J\ulich spin correlation parameters in elastic proton-proton (pp) scattering have been measured with a 2.11 GeV polarized proton beam and a polarized hydrogen atomic beam target. We report results for A$_{NN}$, A$_{SS}$, and A_${SL}$ for c.m. scattering angles between 30$^o$ and 90$^o$. Our data on A$_{SS}$ -- the first measurement of this observable above 800 MeV -- clearly disagrees with predictions of available of pp scattering phase shift solutions while A$_{NN}$ and A_${SL}$ are reproduced reasonably well. We show that in the direct reconstruction of the scattering amplitudes from the body of available pp elastic scattering data at 2.1 GeV the number of possible solutions is considerably reduced.
Spin correlation parameters.
Recent data are presented on spin-spin correlation parameters CLL=(L,L;0,0) and CSL=(S,L;0,0) at forward angles from 1.18 to 2.47 GeV/c incident momenta in proton-proton elastic scattering. Values for ΔσL (inelastic) are derived and are shown to disagree with predictions of theoretical models attempting to describe p−p scattering without dibaryon resonances. Finally, the CLL and CSL data discriminate among various phase-shift solutions, and will lead to a clarification of the p−p phase shifts.
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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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Results are presented of a measurement of the proton-proton elastic-scattering spin parameter CLL=(L,L;0,0) at 11.75 GeV/c and θc.m.=48°−90°. The value of CLL is nearly constant and is approximately -0.16 in this angular region. This behavior is consistent with only one of the many models proposed describing the interaction via the hard scattering of two quarks.
NUMERICAL VALUES OF DATA SUPPLIED BY H. SPINKA.
ESTIMATED VALUE OF CSS (90 DEG) DETERMINED FROM PRESENT DATA ON CLL AND DATA OF CRABB ET AL., (PRL 41, 1257) AND CROSBIE ET AL., (PR D23, 600) FOR CNN VIA THE RELATION CNN-CSS-CLL=1 (90 DEG). ERROR CONTAINS BOTH SYSTEMAT8ICS AND STATISTICS.
Differential cross sections for the elastic scattering of negative pions from hydrogen have been measured over a limited range of squared four-momentum transfer (t) in the vicinity of t≃−3 (GeV/c)2 for incident pion momenta of 2.51, 2.76, and 3.01 GeV/c. These measurements confirm the existence of a minimum in the differential cross section in this region of incident momentum and scattering angle. The minimum occurs at a smaller value of t [t≃−2.6 (GeV/c)2] than has been observed at higher momenta.
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pp-elastic differential cross sections are reported at 492 MeV from 40° to 90°, and at 576, 642, 728, and 793 MeV from 75° to 90° c.m., with an absolute accuracy of less than 1%. These data, obtained with polyethylene targets, agree with recent measurements at the same energies obtained with a liquid-hydrogen target. © 1996 The American Physical Society.
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Absolute pp-elastic-differential cross sections were measured at incident energies 492, 576, 642, 728, and 793 MeV from about 30° to 90° c.m. The total uncertainty was determined to be less than 1%, made possible by particle counting for beam normalization and extensive cross-checks of systematic effects. These new data are consistent with previous data above 600 MeV but have uncertainties about a factor of 10 smaller. Near 500 MeV these data are consistent with 90° data from TRIUMF, but differ significantly from similar data from PSI; the cause of this discrepancy is discussed.
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The π−p elastic scattering differential cross section has been obtained at 18 incident momenta from 1.71 to 5.53 GeV/c. The measurements were taken over a limited range of squared four-momentum transfer t near the forward direction. The statistical accuracy and resolution of these data are comparable to, or better than, existing data. The parameter b in the expression dσdt=Aebt has been determined at each of our incident momenta, and a large (∼25%) enhancement in b as a function of momentum is observed at a c.m. energy of ∼2290 MeV. The relation of this bump in b with the well-established bump in the total π−p cross section at ∼2200 MeV is discussed.
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New high-statistics measurements of π + p elastic scattering differential cross sections are presented at 30 momentum points between 1.282 and 2.472 GeV/ c , covering most of the angular distribution outside the forward diffractive peak. These data show significant disagreements at some momenta with previous high-statistics experiments and with current partial wave analyses.
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