Employing a neutral kaon beam at the Argonne Zero Gradient Synchrotron, a high-resolution magnetic spectrometer, and a neutron detector, differential cross sections have been obtained in the forward direction [0.045<|t|<0.18 (GeV/c)2] for the reaction KL0p→K+n. Previous studies of the time-reversed process in deuterium, K+d→K0p(p), have not yielded direct cross-section measurements in the forward direction because there is an inhibition of the non-spin-flip process in deuterium due to the Pauli exclusion principle. Nevertheless, our data are in agreement with the extracted free-neutron cross sections of deuterium studies as determined from the impulse and closure approximations.
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Measurements of K − p elastic scattering have been carried out at 14 momenta between 610 MeV/ c and 943 MeV/ c over the angular range −0.9 < cos θ < 0.9. The results agree well with the best existing data and have significantly smaller errors.
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DIFFERENTIAL CROSS SECTION AT 0 DEG CALCULATED FROM DISPERSION RELATIONS AND AT 180 DEG INTERPOLATED FROM BUBBLE CHAMBER MEASUREMENTS.
LEGENDRE POLYNOMIAL FIT, INCLUDING FORWARD AND BACKWARD POINTS.
Differential cross-sections for negative pion radiative capture on protons at c.m. angles of 60°, 90°, and 120° have been measured at nine incident laboratory energies between 110 and 270 MeV. Comparison with measured cross-sections for pion photoproduction and with conventional multipole analyses shows neither evidence for a violation of time reversal invariance nor for an isotensor component of the electromagnetic current of hardrons.
Axis error includes +- 0.0/0.0 contribution (QUOTED ERRORS INCLUDE THE 5 PCT AND 3 PCT UNCERTAINTIES IN THE NEUTRON AND PHOTON DETECTOR EFFICIENCIES).
Axis error includes +- 0.0/0.0 contribution (QUOTED ERRORS INCLUDE THE 5 PCT AND 3 PCT UNCERTAINTIES IN THE NEUTRON AND PHOTON DETECTOR EFFICIENCIES).
Axis error includes +- 0.0/0.0 contribution (QUOTED ERRORS INCLUDE THE 5 PCT AND 3 PCT UNCERTAINTIES IN THE NEUTRON AND PHOTON DETECTOR EFFICIENCIES).
Measurements of K + p elastic scattering have been carried out at 13 momenta between 432 MeV/ c and 939 MeV/ c using spark chambers. The data establish unambiguously the constructive interference of the Coulomb and nuclear amplitudes at 432 MeV/ c . The elastic cross section is found to be independent of momentum through the range covered. The phase shifts for S, P, D and F waves are obtained in an energy dependent analysis in which higher waves are held at theoretical values. The initial behaviour ofthe P, D and F amplitudes is quite close to that predicted by the calculation of the peripheral partial waves. Only the P3 and D5 amplitudes become strikingly different with increasing momentum.
COULOMB INTERFERENCE EFFECT SEEN AT SMALL ANGLES.
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We present data from a spark-chamber study of K+p elastic scattering between 432 and 939 MeV/c, over the range −0.6<cosθc.m.<+0.7. With measurements at 13 momenta, and between 2000 events at the lowest momentum and 5000 events at the highest momentum, there is a major improvement over previous data. The elastic cross sections deduced from the differential cross sections are almost independent of momentum through the range covered. The data are inconsistent with counter measurements of the total cross section which suggest a sharp shoulder in the cross section at about 700 MeV/c.
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Photoproduction is studied at 2.8 and 4.7 GeV using a linearly polarized monoenergetic photon beam in a hydrogen bubble chamber. We discuss the experimental procedure, the determination of channel cross sections, and the analysis of the channel γp→pπ+π−. A model-independent analysis of the ρ0-decay angular distribution allows us to measure nine independent density-matrix elements. From these we find that the reaction γp→pρ0 proceeds almost completely through natural parity exchange for squared momentum transfers |t|<1 GeV2 and that the ρ production mechanism is consistent with s-channel c.m. helicity conservation for |t|<0.4 GeV2. A cross section for the production of π+π− pairs in the s-channel c.m. helicity-conserving p-wave state is determined. The ρ mass shape is studied as a function of momentum transfer and is found to be inconsistent with a t-independent Ross-Stodolsky factor. Using a t-dependent parametrization of the ρ0 mass shape we derive a phenomenological ρ0 cross section. We compare our phenomenological ρ0 cross section with other experiments and find good agreement for 0.05<|t|<1 GeV2. We discuss the discrepancies in the various determinations of the forward differential cross section. We study models for ρ0 photoproduction and find that the Söding model best describes the data. Using the Söding model we determine a ρ0 cross section. We determine cross sections and nine density-matrix elements for γp→Δ++π−. The parity asymmetry for Δ++ production is incompatible with simple one-pion exchange. We compare Δ++ production with models.
FROM QUOTED TOPOLOGICAL CROSS SECTIONS. 1.44 GEV CROSS SECTION PUBLISHED PREVIOUSLY.
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NO TMIN CORRECTION HAS BEEN MADE.
A magnetic spectrometer and counter telescope system was used to detect positive pions photoproduced singly in a liquid hydrogen target. Measurements of the differential cross section were made at mean laboratory photon energies, k = 1.1, 1.2, 1.3, and 1.4 GeV and in the angular range from 5° to 165 ° in the center-of-momentum system of the pion. The shape of the angular distribution of the differential cross sections at each value of k is very similar to that of the previously measured distribution at k = 1.0 GeV. The angular distributions were integrated to give the total cross sections. The third pion-nucleon "resonance" peak is seen to be very close to k = 1.0 GeV. A leveling off of the total cross section at k = 1.4 GeV may be due to the fourth "resonance". The accurate small angle data at k = 1.1 and 1.2 GeV permitted a reasonable extrapolation of the differential cross section to the pion-nucleon pole. The value of the pion-nucleon coupling constant, f, was extracted from this extrapolation. The result was f^2 = 0.078 ± 0.011.
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