Data are presented for the reaction ep → ep π 0 at a nominal four-momentum transfer squared of 0.5 (GeV/ c ) 2 . The data were obtained using an extracted electron beam from NINA and two magnetic spectrometers for coincidence detection of the electron and proton. Details are given of the experimental method and the results are given for isobar masses in the range 1.19 – 1.73 GeV/ c 2 .
No description provided.
No description provided.
No description provided.
Angular distributions for photon scattering from C12 and He4 have been measured using continuous wave bremsstrahlung from the Saskatchewan Accelerator Laboratory pulse stretcher ring. Data for carbon were taken at 158.8, 195.2, 197.2, 247.2, and 290.2 MeV end-point energies, and for helium were taken at an end-point energy of 158.8 MeV. A large NaI(Tl) gamma ray spectrometer with 1.7% resolution was used to detect the scattered photons at laboratory scattering angles ranging from 20° to 150°. The excellent energy resolution of the NaI detector allowed a separation of elastic from inelastic photon scattering for the first time at these energies. The angular distributions for elastic scattering are in only fair agreement with delta-hole theory and theory based on the optical theorem at forward angles, and completely disagree with theory at backward angles. Measured cross sections for inelastic scattering leading to the 4.43 MeV state in carbon are small compared to the elastic scattering at forward angles, but are dominant at backward angles. This experiment is the first to separate elastic from inelastic photon scattering at these energies.
ROI=4.43 MEV.
ROI=4.43 MEV.
ROI=4.43 MEV.
The proton Compton effect has been studied in the region between the threshold for pion photoproduction and the Δ(1232). The measurements were performed using bremmstrahlung from the high duty-factor electron beam available at the Saskatchewan Accelerator Laboratory. Elastically scattered photons were detected with an energy resolution of approximately 1.5% using a large NaI total absorption scintillation detector. Differential cross sections were measured for photon energies in the range 136 MeV≤Eγ≤289 MeV and for angles in the range 25°<θlab<135°. The angular distributions and the excitation functions derived from these data are in agreement with recent theoretical analyses. The results were interpreted within a formalism based in part on dispersion relations to obtain model-dependent estimates of the electric and magnetic polarizabilities, α¯ and β¯. We find, subject to the dispersion sum rule constraint α¯+β¯=(14.2±0.5)×10−4 fm3, that α¯=(9.8±0.4±1.1)×10−4 fm3 and β¯=(4.4∓0.4∓1.1)×10−4 fm3, which are consistent with the best previous measurements.
Axis error includes +- 3/3 contribution (DUE TO THE CALIBRATION).
Axis error includes +- 3/3 contribution (DUE TO THE CALIBRATION).
Axis error includes +- 3/3 contribution (DUE TO THE CALIBRATION).
We have measured np→dπ0 cross sections at eleven beam energies within 16 MeV of threshold. Total cross sections are only 0.67±0.10 of the value which has been generally accepted for s-wave pion production strength near threshold. The differential cross sections are anisotropic at only 1 MeV (c.m.) above threshold. Our results are compared to π+d→pp data and to predictions of two models.
Error quoted contains 2 PCT statistical uncertainty in acceptance measurement.
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