Seventeen differential cross sections of the pion-nucleon charge-exchange reaction have been measured at total center-of-mass energies of 1245, 1337, and 1363 MeV. Most measurements are based on the neutron-photon coincidence method, using carefully calibrated neutron counters and an efficient, large-area photon detector. The results are used to test the predictions of charge independence, with which they agree. The results also confirm the Ayed-Bareyre-Sonderegger phase-degeneracy hypothesis at θ̃π0=180°.
No description provided.
No description provided.
No description provided.
The polarisation of the recoil sigma in the reaction π + p → K + Σ + has been measured at 12 production angles at a beam momentum of 1.11 GeV /c using counters and spark chambers. The new data are compared with existing phase shift solutions of π p → K Σ channels in the low energy region.
THE ASYMMETRY PARAMETER, ALPHA, FOR SIGMA+ --> P PI0 IS CLOSE TO -1. THE LAST DATA VALUE IS DEDUCED FROM ALL THE EXPERIMENTAL EVENTS.
Results are presented of a wire-spark-chamber spectrometer measurement of the differential cross section for π−p elastic scattering at 14.15 GeV/c. The region covered in the square of the four-momentum transfer, t, is 0.01<−t<0.78 (GeV/c)2. The cross section is found to obey very nearly a simple exponential t dependence with no evidence of structure. A fit to the data of the form dσdt∝exp(bt+ct2) on the range 0.05<−t<0.78 (GeV/c)2 (i.e., above the region affected by Coulomb scattering) yields b=8.26±0.10 (GeV/c)2 and c=1.01±0.17 (GeV/c)−4. Considering the results of previous measurements, b≃11 (GeV/c)−2 for −t<0.05 (GeV/c)2, a deviation from the simple exponential near −t≃0.05 (GeV/c)2 is indicated.
No description provided.
The differential cross sections of π−p→γn at center-of-mass energy Ẽ=1363, 1337, and 1245 MeV are presented. The angular distributions are compared with recent γn→π−p experiments. Though the cross sections for π−p→γn are somewhat lower than those for the inverse reaction, when all uncertainties are considered, we find that our data are in acceptable agreement at all three energies with the inverse reaction determined from π−π+ ratio measurements, in support of time-reversal invariance. The agreement with bubble-chamber measurements at Ẽ=1363 and 1337 MeV is less satisfactory. The isotensor dip test applied to our data is inconclusive. Our measurements are compared with many multipole analyses, disagreeing with most, in particular with pure fixed- t dispersion relation calculations. We find no evidence, in the sense suggested by Donnachie, for the classification of the P11(1470) resonance in an SU(3) antidecuplet. The data are consistent with a small radiative decay of the P11(1470) resonance, as predicted by quark models.
Axis error includes +- 6/6 contribution.
Axis error includes +- 4.5/4.5 contribution.
Axis error includes +- 4.2/4.2 contribution.
In exposures of the Argonne National Laboratory 12-ft bubble chamber filled with hydrogen and deuterium to a neutrino beam, we have observed events consisting of (1) a single π+ meson originating in the liquid, and (2) a proton with an e+e− pair pointing to it. Only a small fraction of these events can be ascribed to known reactions such as np→nnπ+ and np→npπ0. The remaining events, which correspond to a signal of about 4.5 standard deviations, we ascribe to the reactions νp→νnπ+ and νpπ0.
No description provided.
Differential cross sections for π−p→π0n at five angles for 239, 264, 295, 323, and 375 MeV/c incident pions are presented. The measurements employ the neutron-photon coincidence method, using carefully calibrated neutron counters and an efficient, large-area photon detector. Good agreement is found with the results of the CERN phase-shift analysis.
Axis error includes +- 6.3/6.3 contribution.
Axis error includes +- 5.5/5.5 contribution.
Axis error includes +- 5.2/5.2 contribution.
Differential cross-section measurements are presented for π−p→γn at five energies around the p33(1232) resonance. A detailed comparison is made with γn→π−p deduced from γd experiments. In general, the results are in support of detailed balance. Using the Christ-Lee-Donnachie-Shaw model, our new data indicate that the T-violating phase in the isovector part of the M1+ multipole is less than 2°, which is a very sensitive test of time-reversal invariance. No evidence is found for a possible isotensor component of the electromagnetic current. Our data are compared to various multipole analyses. In general, the agreement is poor.
Axis error includes +- 6.3/6.3 contribution.
No description provided.
No description provided.
Λp interactions have been studied at momenta up to 24 GeV/ c using a new bubble chamber technique. We find that the Λp elastic cross section has fallen to approximately 6 mb at the highest momentum. Results are presented on Λ p→ Λ p π + π − for the first time above 5 GeV c .
No description provided.
No description provided.
ESTIMATE.
We present data on the inclusive neutron spectra produced in the forward direction by the interactions of 23.85 GeV/ c protons in a copper target. The results are in good agreement with the predictions of the triple-Regge model.
No description provided.
Results are presented for the quasi two-body hypercharge exchange reactions of the type using data from a high statistics bubble chamber experiment. Total and differential cross sections and the momentum transfer dependence of the meson and hyperon resonance single density matrix elements are discussed. Amplitude analyses are performed for the first two reactions. The results are compared with quark model and duality predictions and with those from other related reactions.
No description provided.
No description provided.
No description provided.
Forum