The invariant double-differential cross section, E 1 E 2 d 6 σ / d p 3 1 d p 3 2 , and the double-spin asymmetry, A LL , for inclusive multi-γ pair production in which γ-rays came from neutral mesons were measured with a 200 GeV / c longitudinally-polarized proton beam and a longitudinally-polarized proton target. Most of the multi-γ pairs comes from two-jet type events which are sensitive to partonic interaction. The A LL values were found to be consistent with zero. The invariant double-differential cross section for inclusive π 0 π 0 production was also measured. These measured cross sections are consistent with LUND Monte Carlo simulations. Using the LUND Monte Carlo simulation package with the Carlitz-Kaur model of spin dependent distribution functions of valence quarks, the A LL values have been compared with theoretical predictions of gluon polarization, ΔG / G . The results put restrictions on the size of ΔG / G in the region of 0.05 ⪅ x ⪅ 0.35.
No description provided.
No description provided.
No description provided.
The depolarization parameter D 0 n 0 n in the charge-exchange reaction p p ↑→ n n ↑ has been measured for the first time at the CERN Low Energy Antiproton Ring (LEAR) at 875 MeV/ c antiproton beam momentum, in the forward hemisphere. The measured values of D 0 n 0 n are always smaller than ±0.3, indicating that the two-spin amplitudes dominate the scattering matrix as suggested by the meson exchange potential models.
No description provided.
The spin-rotation parameters A and R and the related spin-rotation angle β have been measured for π+p and π−p elastic scattering using protons polarized in the scattering plane. The pion-beam momenta are 427, 471, 547, 625, and 657 MeV/c and the angular range is −0.9≤cosΘc.m.≤0.3. The scattered pion and recoil proton were detected in coincidence, using a scintillator hodoscope for the pions, and the Large Acceptance Spectrometer combined with the JANUS polarimeter for the recoil protons. The results are compared with the four recent πN partial wave analyses (PWA's). Our data show that the major features of these PWA's are correct. The A and R measurements complete our program of pion-nucleon experiments, providing full data sets at three of the above beam momenta. Such sets can be used to test the constraints in the PWA's or to obtain a model-independent set of πN scattering amplitudes.
BETA is the spin-rotation angle.
BETA is the spin-rotation angle.
BETA is the spin-rotation angle.
Final results are presented for the spin-spin correlation parameters CSL and CLL for np elastic scattering with a polarized neutron beam incident on a polarized proton target. The beam kinetic energies are 484, 634, and 788 MeV, and the c.m. angular range is 80°-180°. These data will contribute significantly to the determination of the isospin-0 amplitudes in the energy range from 500 to 800 MeV.
Pure np elastic scattering spin variables. CLL and CSL derived from measured combined spin variable. Thus the errors on CLL and CSL are slightly correlated. There are also additional systematic errors of 7 pct associated with beam and 3.3 pct target polarizations respectively.
Pure np elastic scattering spin variables. CLL and CSL derived from measured combined spin variable. Thus the errors on CLL and CSL are slightly correlated. There are also additional systematic errors of 7 pct associated with beam and 3.3 pct target polarizations respectively.
Pure np elastic scattering spin variables. CLL and CSL derived from measured combined spin variable. Thus the errors on CLL and CSL are slightly correlated. There are also additional systematic errors of 7 pct associated with beam and 3.3 pct target polarizations respectively.
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.
No description provided.
No description provided.
No description provided.
The two-spin parameter A LL in inclusive π 0 productionby longitudinally-polarized protons and antiprotons on a longitudinally-polarized proton target has been measured at the 200 GeV Fermilab spin physics facility, for π 0 's at x F =0 with 1⩽ p t ⩽3 GeV/ c . The results exclude, at the 95% confidence level, values of A LL (pp) > 0.1 and < − 0.1 for π 0 's produced by protons, and values of A LL ( p p) > 0.1 and < −0.2 for incident antiprotons. The relevance of A LL (pp) for the gluon spin density is discussed. The data are in good agreement with “conventional”, small or zero, gluon polarization.
No description provided.
The first spin-transfer observables for the πd→pp reaction have been measured at a number of energies spanning the Δ resonance in this system. These parameters correspond to KSL and KSS of the pp→dπ reaction for incident proton energies ranging from 600 to 800 MeV. Such data can provide an important constraint on the determination of the partial-wave amplitudes describing this fundamental reaction. The discrepancies between our data, theoretical predictions, and values calculated from published partial-wave amplitudes demonstrate the need for further work in this area.
No description provided.
No description provided.
In order to improve existing I=0 phase shift solutions, the spin correlation parameter ANN and the analyzing powers A0N and AN0 have been measured in n-p elastic scattering over an angular range of 50°–150° (c.m.) at three neutron energies (220, 325, and 425 MeV) to an absolute accuracy of ±0.03. The data have a profound effect on various phase parameters, particularly the P11, D23, and ε1 phase parameters which in some cases change by almost a degree. With the exception of the highest energy, the data support the predictions of the latest version of the Bonn potential. Also, the analyzing power data (A0N and AN0) measured at 477 MeV in a different experiment over a limited angular range [60°–80° (c.m.)] are reported here.
The beam analysing power at incident kinetic energy 220 MeV. Additional systematic uncertainty of +- 0.015 and a scalar error of 3.5 PCT.
The beam analysing power at incident kinetic energy 325 MeV. Additional systematic uncertainty of +- 0.018 and a scalar error of 3.1 PCT.
The beam analysing power at incident kinetic energy 425 MeV. Additional systematic uncertainty of +- 0.022 and a scalar error of 3.3 PCT.
The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured in the range 0.01<×<0.7. The spin dependent structure function g 1 ( x ) for the proton has been determined and, combining the data with earlier SLAC measurements, its integral over x found to be 0.126±0.010(stat.)±0.015(syst.), in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Biorken sum rule, this result implies a significant negative value for the integral of g 1 for the neutron. These integrals lead to the conclusion, in the naïve quark parton model, that the total quark spin constitutes a rather small fraction of the spin of the nucleon. Results are also presented on the asymmetries in inclusive hadron production which are consistent with the above picture.
THE MEAN Q**2 FOR EACH OF THE 10 VALUES OF X BELOW ARE 3.5,4.5,6.0, 8.010.3,12.9,15.2,18.0,22.5,29.5.
No description provided.
No description provided.
The polarization parameter Pn000, the two-spin parameters Dn0n0, Kn00n, Ds′0s0, Ds′0k0 and the three-spin parameters Ms′0sn and Ms′0kn have been measured for pp elastic scattering angles between 60° and 88° center of mass at 241 and 314 MeV incident kinetic energies, and between 38° c.m. and 98° c.m. at 341, 366, and 398 MeV. At 473 MeV, only Pn000 and Ds′0k0 were measured between 34° c.m. and 62° c.m. The experiment was performed at SIN using a polarized proton beam and a polarized butanol target. The polarization of the scattered proton was analyzed in a carbon polarimeter. The influence of these high-precision data on the Saclay-Geneva phase-shift analysis is discussed.
Statistical errors only.
Statistical errors only.
Statistical errors only.
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