A graphite-plate spark chamber has been used to analyze the polarization of protons recoiling from π−−p scattering. The observations were made at 90° (c.m. system) pion scattering angle for seven incident pion energies between 500 and 940 Mev, at 120° or 135° for five energies in this interval, and also at 75° for 500 Mev only. The results are compared with predictions of several models used to explain the maxima in the π−−p scattering cross section. Qualitative arguments show that the energy intervals between these maxima are not completely dominated by neighboring single-state resonances. Phase shifts found to be large in scattering also seem to be large in polarization.
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Angular distributions for π0 photoproduction from hydrogen at energies between 660 and 800 MeV and proton center-of-mass angles from 0° to 140° have been measured and analyzed. Some variation from a pure d32 state is seen in the resonance region. A possible high-momentum-transfer enhancement of the cross section is discussed.
Axis error includes +- 0.0/0.0 contribution (3 TO 10////).
Axis error includes +- 0.0/0.0 contribution (3 TO 10////).
Axis error includes +- 0.0/0.0 contribution (3 TO 10////).
The cross section for single π0 photoproduction from hydrogen has been measured at nominal angles of 70°, 90°, 130°, and 180° for photon energies 220-400 MeV by detecting the recoil protons. The 180° measurements, taken with a new setup, avoid big corrections present in some of the previously published results. These new data allow a direct comparison with the experiment presented by the Bonn group and with the most recent theoretical predictions.
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The np and nd total cross sections have been measured directly with a neutron beam with momenta of 4.0 ± 0.6 and 5.7 ± 0.6 GeV/ c . The data are compared with the previous nucleon-nucleon and nucleon-deuteron results, and the deuteron screening term was also evaluated. The measured total cross section are 43.1 ± 0.6 and 80.3 ± 1.9 mb at 4.0 GeV/ c and 42 ± 0.6 and 77.8 ± 1.3 mb at 5.7 GeV/ c .
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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.
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A systematic study of p p and p d reactions producing strange particles between 1.09 and 3.45 GeV/ c has been completed. Reaction and resonance cross-section data are presented at 11 p p and 13 p d momentum settings. Evidence for a broad shoulder in the K K 3π final state near 1.8 GeV/ c is presented and contrasted to previously published work on a portion of the final data sample. No evidence for a p n → K 0 K − ω effect near 1.3 GeV/ c is found, ruling out an association of K K ω effects with the nearby isospin one enhancement in the total cross section. Finally, we find no evidence for a p p → K K ω enhancement near 1.8 GeV/ c .
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The π−+p→π0+n differential cross section at 180° has been measured for 52 values of π− momentum from 1.8 to 6.0 GeV/c using a constant-geometry detection system. The average statistical uncertainty is ∼5% and the systematic uncertainty is ∼10%. The details of the experiment and the data analysis are discussed. The data are compared with those of other experiments with which they are generally in agreement. One set of data disagrees with those presented here and a possible reason for this is discussed. A five-parameter fit of the predictions of a dual-resonance model to our data gave excellent agreement. The differential cross sections at 180° for π±p elastic scattering have been compiled and the moduli and relative phase of the T=12 and T=32 pion-nucleon s- and u-channel amplitudes (|A12|, |A32|, and cosδ) have a minimum at u=0.4 GeV/c and, in the s channel, a corresponding minimum at s=2.2 GeV/c.
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An experiment was done using the new accelerated polarized proton beam at the Argonne National Laboratory zero-gradient synchrotron and a polarized proton target. The total cross section for proton-proton scattering at 3.5 GeV/c was measured in the spin states ↑↑ and ↑↓ perpendicular to the beam direction. The two cross sections were found to be equal within the experimental error of ±5%.
TOTAL CROSS SECTION DIFFERENCE FOR PURE TRANSVERSE SPIN STATES.
Final state resonance production and single particle momentum spectra are presented for p p annihilations into K K and π's between 1.09 and 3.45 GeV/ c . Resonance production generally agrees with the Lamb statistical model. Momentum spectra of K's and π's are independent of incident energy, while the mean multiplicity increases in proportion to the c.m. energy, supporting the annihilation model of Jacob and Nussinov.
THESE CROSS SECTIONS WERE GIVEN IN DETAIL IN B. Y. OH ET AL., NP B51, 57 (1973).
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A systematic study of p p and p d topological and reaction cross sections between 1.51 and 2.90 GeV/ c has been completed. The data have been analysed in relation to the three known structures at c.m. N N energies of 2190, 2350 and 2375 MeV. The data suggest that four- and six-pion annihilations of antiprotons on neutrons may be the source of the 2350 MeV effect. Further data below 1.60 GeV/ c are required to verify this tentative conclusion.
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INCLUDING 3 PCT SYSTEMATIC ERROR.
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