Measurement of np elastic scattering at high energies and very small momentum transfers

The np elastic differential cross section has been measured for incident neutron momenta 100–400 GeV/c in the |t| range 6 · 10^?6 ? 5 · 10^?1 (GeV/c)². The np data of this experiment provide a first direct measurement of the hadronic amplitude for |t| < 10^?2 (GeV/c)², which is consistent with the extrapolations from higher |t| values. Our data for |t| < 10^?4 (GeV/c)² are consistent with a rise which can be attributed to Schwinger scattering, caused by the interaction of the neutron magnetic moment with the proton.     

Proton spin-spin asymmetries for large angle electron-proton elastic scattering

Using the proper-time technique we calculate the one-fermion-loop contributions in four and six derivatives to the effective Lagrangian for theSU(2)xSU(2) non-linear σ-model.     

Differential cross sections for np and nd elastic scattering near 130 MeV

We have measured the np (nd) elastic scattering cross sections at 25(17) angles in the interval 30°–168° (c.m.), using a neutron beam with a broad spectrum peaked near 130 MeV. At backward angles the outgoing charged particles from a liquid hydrogen (deuterium) target were detected; at forward angles we detected neutrons scattered from a hydrogenated (deuterated) scintillating target. Cross sections have been normalized to the energy dependent solution of the Livermore nucleon-nucleon partial wave analysis, evaluated at 130 MeV. The np measurements represent a marginal improvement on previous work; the nd cross sections show some differences from pd measurements, in agreement with earlier indications at an energy of 152 MeV.     

Depolarization in p-N elastic scattering and large tensor spin-spin interaction

We have measured the angular distribution of the depolarization parameter K_y^y′ in p-¹⁵N elastic scattering at 65 MeV. The deviation of K_y^y′ from unity is large and indicates the existence of a nucleon-nucleus spin-spin interaction. The DWBA analysis shows that the measured K_y^y′ data imply a large contribution from the tensor part of the spin-spin potential.     

Comments on np elastic scattering, 142–800 MeV

Important new data of McNaughton et al. on np Wolfenstein parameters are added to NN phase-shift analysis. At 800 MeV, there is a dramatic improvement and one can see with confidence which way phase shifts are heading from 500 to 800 MeV. Dispersive effects in ³D₁ and ³G₃ herald the onset of I = 0 inelasticity. Phase shifts account naturally for the energy dependence of Δσ_L and Δσ_T for np scattering and do not support the claim of Beddo et al. for an I = 0 dibaryon resonance near 733 MeV.     

Impact parameter description of multiparticle and elastic scattering

Impact parameter variables are defined for a multiparticle production process. The equation of unitarity for elastic scattering is written at high energy in terms of these variables. The overall impact parameter can be expressed in terms of the impact parameters of all the produced particles. The unitarity equation becomes an “optical theorem” at each impact parameter — diffractive scattering is given by beam depletion. These features allow this technique to give a much clearer interpretation of unitarity in any model than has therefore been possible. This technique can be used to study existing models, and to suggest new ones.     

Quasiclassical parameter calculation of elastic electron scattering by a xenon atom

A calculation (accurate up to terms in ²) is performed of quasiclassical phase shifts and of differential and total cross sections of elastic electron scattering by a xenon atom in the static field approximation, with and without exchange.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 69–73, October, 1972.The author is grateful to N. I. Zhirinov, under whose guidance this work was performed.     

Measurement of the polarization parameter in pp elastic scattering at 150 GeV/c

The polarization parameter in pp elastic scattering at 150 GeV/c, and in the momentum transfer interval 0.4 ? ?t ? 3.0 GeV², has been measured in an MWPC and scintillation counter experiment at the CERN SPS using a polarized proton target. The polarization is decreasing steadily from zero to ≈ ? 10% in the range 0.4 < ?t < 1.3 GeV²; for higher |t| the data suggests a change of sign. Results are also given for the differential cross section, which exhibits a small dip at ?t = (1.46 ± 0.01) GeV.     

Measurement of the polarization parameter in small angle proton-proton elastic scattering at 6 GeV/c

The polarization parameter in pp elastic scattering was measured at 6 GeV/c with fine t resolution for 0.02 < ?t < 0.5 GeV² using a polarized proton beam with Effective Mass Spectrometer at the Zero Gradient Synchrotron. The polarization rises like √?t in the interval 0.02 < ?t < 0.1 GeV², No statistical significant structure was found in this region of momentum transfer.     

Measurement of the spin rotation parameter Ain the elastic pion-proton scattering at 1.43 GeV/c

The ITEP-PNPI collaboration presents new results of the measurements of the spin rotation parameter A in the elastic scattering of negative pions on protons at P_beam = 1.43 GeV/c. The results are compared to the predictions of several partial wave analyses. The experiment was performed at the ITEP proton synchrotron, Moscow.     

Measurement of the spin correlation Aookk in pp elastic scattering from 0.88 to 2.7 GeV

The spin correlation parameter A_ookk in pp elastic scattering was measured using the SATURNE II polarized proton beam and the Saclay frozen spin polarized target. The measurements at 0.88 and 1.1 GeV were carried out in the angular region θ_CM from 28° to ⋍ 50° and complete our previous measurements from 45° to 90°. Above 1.1 GeV the measurements presented here cover both regions, extending from θ_CM = 28° (at the lower energies) or θ_CM = 18° (at the higher energies) to θ_CM > 90°. The shape of the angular distribution A_ookk (pp) = f(θ_CM) changes considerably between in our energy region.     

Measurement of the polarization correlation parameter C nn in the pp elastic scattering with an unpolarized proton target and an unpolarized 1-GeV proton beam

The polarization correlation parameter C _nn in the elastic proton-proton scattering was for the first time measured with a high statistical accuracy at 1 GeV using an unpolarized proton beam incident on an unpolarized proton target. Both outgoing protons from the reaction were detected in coincidence by means of a two-arm focusing magnetic spectrometer installed at nonsymmetric angles corresponding to the center-of-mass scattering angle Θ_cm = 62.25°. The correlation parameter C _nn , as well as polarizations P ₁ and P ₂ of the secondary protons, were measured by means of multiwire proportional chamber polarimeters placed at the focal planes of each spectrometer arm. The obtained data are compared with the predictions of the phase-shift analysis. The connection with the experiment on C _nn and polarization measurements in the (p, 2p) reaction on ⁴He and other light nuclei in similar kinematics is discussed     

Measurement of spin observables in neutron-proton elastic scattering

The spin correlation parameters and the analyzing power have been measured in free np elastic scattering at kinetic energies of 260, 315, 380, 460 and 535 MeV in the c.m. angle range from 60° to 164°. The experiment was performed at the Paul-Scherrer-Institut (PSI) using a polarized neutron beam with continuous energy incident on a polarized proton target. These data will contribute significantly to the determination of the isospin I=0 nucleon-nucleon amplitudes. Received: 24 May 2000 / Published online: 31 August 2000     

Measurement of the spin correlation parameter Aoonn and of the analyzing power for pp elastic scattering in the energy range from 0.5 to 0.8 GeV

The spin correlation parameter A_oonn and the analyzing powers A_oono and A_ooon were measured simultaneously, in the energy range 0.5–0.8 GeV and in the angular region 40°–80° CM. The experiment used the polarized proton beam of SATURNE II and the Saclay frozen spin polarized target.