The results of the total cross section measurements of neutrons on protons, deuterons and nuclei C, O, Al, Cu, Sn, Pb in the energy range of 28–54 GeV are reported.
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In an experiment with the CERN 2 metre DBC the reaction K$^+$d $\to$ K$^0 \pi^+$d is studied at an incident momentum of 4.6 GeV/c. The cross section is found to be (66 ± 10) μb for four-momentum transfer squared from target to recoil deuteron greater than 0.02 GeV 2 , and the reaction is dominated by the production of K$^*+$ (892) via natural parity exchange. Using data for the reactions K$^\pm$d $\to$ K$^{*\pm}$(892)d in the incident momentum range 2–13 GeV/ c the parameters of the effective exchanged trajectory are estimated.
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A systematic analysis is presented on the reaction K + p → K ∗0 (890) Δ ++ for nine incident momenta between 4.6–16.0 GeV/ c . Cross sections, differential cross sections and vector meson single density matrix elements are given. As a function of energy, little if any change is observed in either the shapes of the differential cross sections or in the values of the density matrix elements. The data are interpreted in terms of current ideas on t -channel exchange mechanisms.
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21 differential cross section measurements of the np → pn charge-exchange reaction have been carried out at the synchrotron Saturne (Saclay), for incident neutron momenta between 1 and 2 GeV/ c and in the squared four-momentum transfer range 0 ⩽ −t ⩽ 0.4 (GeV/ c ) 2 . The π exchange peak is seen at all the incident momenta. The s dependence of the very forward slope of this peak shows weak structures near the threshold of inelastic channels.
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The reaction e − + p → e − + p + η has been studied in the region of the S 11 (1535)-resonance by detecting the recoil proton in coincidence with the scattered electron. The reaction has been observed at three four-momentum transfers of the virtual photon: q 2 = 0.2, 0.28 and 0.4 (GeV/ c ). First results of the differential cross section measurements are given and compared with quark model calculations.
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Data have been taken at the φ energy with the same large solid angle detector which has been used for the measurement of the ϱ and ω production by e + e − annihilations. From the φ → K o L K o S π + φ − excitation curve we have deduced the φ width Γ φ = (3.81 ± 0.37) MeV and the cross-section σ e + e − → K o L K o S = (1.48±0.08±0.12) μ b. (the quoted errors are respectively statistical and systematical.)
EXPERIMENTAL CROSS SECTION INCLUDING RADIATIVE EFFECTS.
FITTED CROSS SECTION AT PHI PEAK, RADIATIVELY CORRECTED.
K + p elastic scattering has been measured over nearly the whole angular range at an incident momentum of 10 GeV/ c . The differential cross-section is found to decrease smoothly in the forward direction to - t ≈ 2 (GeV/ c ) 2 , where there is a change in slope, followed by a further decrease to - t ≈ 6 (GeV/ c ) 2 . Around 90° c.m. the cross-section is approximately 1 nb/(GeV/ c ) 2 , which is more than two orders of magnitude lower than at 5 GeV/ c . The backward peak has no structure.
THESE DATA ARE REPORTED MORE FULLY IN C. BAGLIN ET AL., NP B98, 365 (1975).
A large solid angle detector has been used to observe π + π − π o events produced at the φ energy by electron-positron collisions in the Orsay storage ring. Fitting our data with a Breit and Wigner curve, with a fixed width Γ = (3.8±0.4) MeV coming from K O S K O L analysis, we deduce σ e + e − → π + π − π O = (0.70±0.13) μ bat 2 E = Mφ . Using our measurements on the other φ decay modes we deduce ( φ → π + π − π o )/( φ → K o S K o L ) = 0.47±0.06 and ( φ → η o γ )/( φ → K o S K o L ) = 0.077±0.022. Assuming ( φ → K + K − )/( φ → K o S K o L ) = 1.60, we derive σ TOT = (4.7±0.4) μ b, Γ e + e − = (1.27±0.11 keV and g 2 o /4 π = 14.3±1.3 (without finite width correction). Furthermore (from the observation of the ππγ coplanar events) we put an upper limit to the mode e + e − → φ π + π − γ , Γ ( φ → π + π − γ ) ⩽ 0.007 Γ ( φ → Total ) with 90% C.L.
EXPERIMENTAL CROSS SECTIONS INCLUDING RADIATIVE EFFECTS.
FITTED PARTIAL AND TOTAL CROSS SECTION AT PHI PEAK, RADIATIVELY CORRECTED.
The angular distribution of π + p elastic scattering has been measured at an incident momentum of 10 GeV/ c . Nearly the whole angular range was covered in one experimental set-up. The pronounced dip at − t = 2.8 (GeV/ c ) 2 , observed at lower momenta, has diminished and is essentially a shoulder at 10 GeV/ c . The other structure at larger momentum transfers are also different in detail from what we observed at 5 GeV/ c . In the 90° c.m. region the differential cross-section is approximately one nb/(GeV/ c ) 2 , which is more than two orders of magnitude lower than at 5 GeV/ c .
THESE DATA ARE REPORTED MORE FULLY IN C. BAGLIN ET AL., NP B98, 365 (1975).
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