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Approximately 60 000 events have been collected in a spark chamber experiment at the CERN Proton Synchrotron which studied elastic diffraction scattering of π--p and p-p at incident momenta of 8.5, 12.4 and 18.4 GeV/c and of π+-p at 8.5 and 12.4 GeV/c. Magnetic analysis of the incoming and diffraction scattered particle, together with measurement of all angles, permitted each event to be determined as elastic subject to three constraints, so that the inelastic background was rejected with. high efficiency, even at the larger momentum, transfers. Much of the data have been processed by the CERN Automatic Flying-Spot DigitizerHPD. A detailed description of the experimental technique and of the methods of analysis is given. The results, together with data from lower energies, confirm the remarkable energy-independence of the shape of the pion-proton diffraction scattering peak up to |t| = 1.5 (GeV/c)2, wheret is the square of the four-momentum transfer, over a range of pion energies from 2 to 18 GeV. Proton-proton scattering does however appear to show a shrinking diffraction peak. In general, the data agree with other experiments using both counter and bubble chamber techniques, but some differences do appear. During the experiment, data were taken which set an upper limit of 2·102 μb/(GeV/c)2 on the differential elastic cross-section dσ/dt over a range of |t| from 20.9 to 23.4 (GeV/c)2 at 13.4 GeV/c incident pion momentum.
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π±p elastic differential cross sections in the momentum range 1.72-2.80 GeV/c have been measured at the proton synchrotron "NIMROD" of the Rutherford High Energy Laboratory. The results are tabulated, and analyses of the differential cross sections employing optical models and Legendre polynomial expansions are advanced. A critical discussion of a recent interpretation of differential-cross-section structure in terms of interference between resonant and background amplitudes is presented.
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Differential cross sections for the reactions e−+p→e−+p+π0 and e−+p→e−+n+π+ have been measured near the Δ(1236) resonance at four-momentum transfers of 0.05, 0.13, 0.25, and 0.4 (GeV/c)2. A few measurements of the π+ angular distribution have been obtained at a four-momentum transfer of 0.6 (GeV/c)2. Cross sections for the π0 reaction are compared with dispersion-theory predictions at several pion-nucleon c.m. energies for each four-momentum transfer. A phenomenological analysis of the π0 results leads to the determination of the magnetic dipole and electric quadrupole partial-wave amplitudes and the γNΔ transition form factor. Evidence is found for the existence of a significant scaler-transverse interference term in the cross section, which is tentatively associated with the resonant scaler quadrupole interaction. Cross sections for π+ electroproduction are compared with dispersion theories using the pion form factor as a free parameter. The results suggest a form factor similar to that of the proton. A fit to the form-factor results, using the ρ-dominance model, requires mρ=560±80 MeV. The rms pion charge radius is estimated to be 〈r2〉12=0.86±0.14 F.
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We have measured the p¯n differential elastic cross section for −t≥0.15 (GeV/c)2. We compare our data with existing data from p¯p and np elastic scattering experiments in this energy region. Our data show a dip in the cross section at −t≃0.45 (GeV/c)2 and a secondary maximum at −t≃0.7 (GeV/c)2. We see no evidence for backward peaking in p¯n elastic scattering at this energy. Evidence is presented for I=1, t-channel exchange in N¯N scattering.
'1'. '2'. 'GLAUB'.
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We present results of an experiment to measure the differential cross section of the reaction π−p→π0n between the forward and backward peaks. The measurements were made at incident π− momenta of 3.67 and 4.83 GeVc. The t range 1.7<~|t|<~4.9 (GeVc)2 was covered at the lower momentum and 1.8<~|t|<~7 (GeVc)2 at the higher momentum. At the lower momentum the cross section is essentially constant between |t|=2.4 and 4.8 (GeVc)2 while at the higher momentum the angular distribution exhibits a broad minimum centered at |t|=4.4 (GeVc)2.
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A measurement of the differential cross section for the reaction n + p → d + π° has been made using a neutron beam with kinetic energies up to 720 MeV. The angle and momentum of the deuterons were measured using an analyzing magnet and wire spark chambers with a magnetostrictive readout. The photons from the decaying π° were not detected. The neutron energy was calculated from the measured deuteron angle and momentum. The cross sections are compared to those for the reaction π + + d ⇆ p + p as a test of isotopic spin invariance in strong interactions. The symmetry of the cross sections about 90° is also investigated, and an upper limit of about 1% is placed on the real part of the ratio of isospin-violating to isospin-conserving amplitudes.
EKIN IS 325 TO 675 MEV.
Data for the reactionπ + p→f o Δ ++ at 13.1 GeV/ c is presented and discussed within a Reggeized pion exchange model with absorption.
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NUMERICAL VALUES TAKEN FROM THE COMPILATION PDG2 (CHEW 73B). READ FROM GRAPH.
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A sample of approximately 250 Λp interactions has been obtained in the Λ-hyperon momentum range of about 300 to 500 MeV/ c . An enhanced Λ-hyperon production rate was obtained by exposing an internally-mounted platinum target to the incident 1.5 GeV/ c meson beam. Cross sections and angular distributions are obtained for the reactions: Λ p → Λ p, Λ p → Σ o p and Λ p → Λ p π o . In the elastic channel, no strong evidence is seen near the Σ o p threshold for the presence of a 3 S 1 resonance, which has been reported, although there is some evidence for a small enhancement in this mass region. There is evidence for the presence of P-waves and probably also D-waves above about 800 MeV/ c , but not below this momentum.
D(SIG)/DOMEGA IS ANALYSED IN TABLE 2 BY LEGENDRE POLYNOMIAL EXPANSION. ERRORS ADDED AS 1/SQRT(EVENTS).
D(SIG)/DOMEGA IS ANALYSED IN TABLE 2 BY LEGENDRE POLYNOMIAL EXPANSION. ERRORS ADDED AS 1/SQRT(EVENTS).
D(SIG)/DOMEGA IS ANALYSED IN TABLE 2 BY LEGENDRE POLYNOMIAL EXPANSION. ERRORS ADDED AS 1/SQRT(EVENTS).
A measurement of the differential cross section for the reaction np→ π 0 d has been made at the Lawrence Radiation Laboratory 184-inch cyclotron. A neutron beam with kinetic energies up to 720 MeV was incident on a liquid hydrogen target. The angle and momentum of the deuterons were measured using an analyzing magnet and wire spark chambers with a magnetostrictive readout. Deuterons were separated from protons by time-of-flight. The photons from the decaying π 0 were not detected. The neutron energy was calculated from the measured deuteron angle and momentum.
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