Positive Pion Photoproduction from Hydrogen for Incident Photon Energies 300-750 MeV

Abstract

The differential cross section for the reaction y+p-^w+n was measured at 19 photon energies between 300 and 750 MeV in the laboratory frame, for pion angles between 0° and 130° in the cm. system. The pions were analyzed in angle and momentum with a magnetic spectrometer and detected by a counter telescope. The 0° measurements could be achieved, in spite of the excessive positron rate, owing to a mass-spectrometer arrangement. No direct indication for the electromagnetic excitation of the Pn resonance (1466 MeV) was found. Comparison is made with theoretical calculations of w + photoproduction.

Measurement of Inverse Pion Photoproduction Near theP330(1236)Resonance

“…The normalization uncertainty is 7%. the TT + data of Beale, Ecklund, and Walker, 15 Betourn£ et al, 16 and Fisher et al, 16 a dip in A near the peak of the P 33 resonance and if the model of Sanda and Shaw is correct, we confirm the existence of an isotensor component of the electromagnetic current, as originally deduced by Sanda and Shaw from yd experiments. In the following Letter 17 we present a fit of our measured angular distributions to various sets of multipoles with and without an isotensor amplitude.…”

Analysis of pion photoproduction data

“…[66]. • are from Orsay [51] (black circles), SLAC [52] (open circles), [53] (open triangles), [54] (black square), and DESY [55] (black diamonds.) The solid (dash-dotted) line represents the SM02 (MAID2001 [44]) solution.…”

“…Plotted are the SM02 (solid line), the 162 MeV-SES (158 − 165 MeV) fit associated with SM02 (dotted lines represent uncertainties of the SES fit) and the MAID2000 results (dash-dotted) [44]. [51] (black circles), SLAC [52] (open circles), [53] (open triangles), [54] (black square), and DESY [55] (black diamonds.) The solid (dash-dotted) line represents the SM02 (MAID2001 [44]) solution.…”

Photoproduction of pions and properties of baryon resonances from a Bonn-Gatchina partial-wave analysis

“…Total cross sections were reported in [73][74][75][76][77][78][79][80][81][82][83][84][85][86][87]. Again, some discrepancies show up, at energies above 1600 MeV and in the forward region, between the new CLAS data and former measurements.…”