Differential cross sections for the reaction π−p→π0n were measured at nine incident-pion kinetic energies in the interval from 500 to 1300 MeV. The negative pion beam from the bevatron was focused on a liquidhydrogen target completely surrounded by a cubic array of six steel-plate spark chambers. The spark chambers were triggered on events with neutral final states. Charge-exchange events were identified from the one-shower and two-shower events in the spark-chamber pictures. By the Monte Carlo technique, the π0 distributions were calculated from the bisector distributions of the two-shower π0 events together with the observed γ-ray distributions of the one-shower π0 events. These π0 distributions were fitted with both Legendre-polynomial expansions and power-series expansions by the method of least squares. The extrapolated forward differential cross sections are in good agreement with the dispersion calculations. The Legendre coefficients for the differential cross sections in isospin state T=12 were obtained by combining our results with available data on π±p elastic scattering. In the light of existing phase-shift solutions, the behavior of these coefficients is discussed. The D5F5 interference term that peaks near 900 MeV is verified to be in isospin state T=12 only. We report here also the total neutral cross sections and the cross sections for the production of neutral multipion final states 2π0n and 3π0n. The 4π solid angle and the calibrated energy response of the spark chambers contribute to the accuracy of the results.
No description provided.
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Polarization and differential cross-section data for elastic scattering of positive pions on protons between 0.82 and 2.74 GeV/ c are presented. A dip in the polarization, at constant u ≈ −0.65 GeV 2 , is observed. The data are compared with published phase-shift analyses.
No description provided.
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Polarization and differential cross-section data for elastic scattering of negative kaons on polarized protons between 865 and 1330 MeV/ c are presented. Comparisons are made with predictions given by published energy dependent phase-shift analyses. The Legendre expansion coefficients characterizing the polarization distributions show remarkable structures resulting from excitation of Λ- and Σ-resonances. An analysis of the elastic and charge-exchange data in this region of momenta supports the assignments of J P = 3 2 + for the Λ(1870) resonance. The occurence of zero crossings in the polarization data is discussed.
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We have studied the process p¯p into π+X− using wire spark chambers. The data cover the angular range of cosθp¯π+* between 0.96 and 1.0 at several incident momenta between 1 and 2 GeVc. The reaction p¯p→π+ρ− was observed with (dσdΩ)* of the order of 100 μb/sr at several momenta.
READ FROM GRAPH.
The π+ photoproduction cross section in hydrogen has been measured at 180° for photon energies from 0.22 to 3.1 GeV by detecting the pion in the backward direction. The statistical accuracy of the measurements varies typically from 3 to 10% depending on the energy. The data are compared with other recent experimental results and predictions of phenomenological theories.
No description provided.
Electron-proton elastic scattering cross sections have been measured to determine the proton electromagnetic form factors at squared four-momentum transfers q 2 between 10 and 50 fm −2 . At these values of q 2 we measured angular distributions between 25° and 110° and in addition at 25° and 35° cross sections for q 2 from 2 to 20 fm −2 using the external electron beam of the Bonn 2.5 GeV electron synchrotron. Our results confirm deviations from the scaling law.
Axis error includes +- 2/2 contribution (NORMALIZATION ERROR).
Axis error includes +- 2/2 contribution (NORMALIZATION ERROR).
Axis error includes +- 2/2 contribution (NORMALIZATION ERROR).
Multihadron production by electron-positron colliding beams has been investigated for total centre-of-mass energies ranging from 1.2 to 2.4 GeV. The total cross-section, σtot ≡ σ(e+e−→π+π−+ + anything), is of the order of σμμ ≡ σ(e+e−→μ+μ−), with a threshold near 1 GeV. Partial cross-sections for the various channels are also derived. The cross-section of the specific channel e+e−→π+π−π+π− exhibits an energy dependence which is suggestive of a heavier vector meson, ρ' (mρ,≈ 1.6 GeV,Гρ, ≈ 350 Mev), having the same quantum numbers as the ρ-meson. An upper limit is given for the coupling constantfρ′ (fρ′/4π<18, wherefρ′=mρ′2e/gγρ′). Final states withG+ parity are found to be much more abundant than those withG− parity. The average multiplicity (charged plus neutral final-state pions) is found to be betweet 4 and 5 over all the energy range explored.
No description provided.
VALUES OF R CALCULATED FROM TOTAL CROSS SECTION.
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With an apparatus slightly improved with respect to a previous one we have studied multihadronic production at the Adone e + e − storage ring up to a maximum center of mass energy of 3 GeV.
No description provided.
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The results of an experiment performed at Adone, the 2×1.5-GeV e+e− Frascati storage ring, are presented. During ∼ 1500 hours of running time a total of 5164 electron-positron elastic scattering events (integrated luminosity L=3.5×1035 cm−2) and 605 noncoplanar events from the reaction e+e−→a±+b±+anything (effective integrated luminosity L=2.5×1035 cm−2) have been collected at c.m. energies ranging from 1.4 to 2.4 GeV. Over the energy range explored (1.4-2.4 GeV), corresponding to an average q2 ranging from 0.8 to 2.4 (GeV/c)2, the yield of wide-angle (60°<θ<120°) electron-positron elastic scattering events is found to be in good agreement with the predictions of quantum electrodynamics (QED) (R=σexpσQED=1.05±0.04). The noncoplanar events appear to be of a hadronic nature and are produced with a much higher cross section than predicted on the basis of ρ, ω, φ dominance at these energies. The total cross section for the reaction e+e−→a±b±+anything shows a rapid increase to ∼ 90 nb between 1.0 and 1.5 GeV and falls off slowly to ∼ 50 nb at 2.4 GeV. Cross sections for some of the channels contributing to this multihadron process (e+e−→π+π−π+π−, e+e−→π+π−π+π−+neutrals, e+e−→3π+3π−) have been determined and are reported.
DATA VALUES MEASURED FROM GRAPH IN JOURNAL.
VALUES OF R CALCULATED FROM TOTAL CROSS SECTION.
We present new data on the reaction K−p→Λη from 0.80 to 1.84 GeV/c. An interpretation is attempted in terms of the formation of known hyperon resonances.
THE ORIGINAL DATA AT 49 MOMENTA HAVE BEEN GROUPED INTO 27 MOMENTUM BANDS. SIG = 4*PI*(REDUCED CM K- WAVELENGTH)**2*LEG(L=0).
DATA FURTHER GROUPED INTO 9 MOMENTUM REGIONS.
DATA FURTHER GROUPED INTO 9 MOMENTUM REGIONS.