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Single-π 0 Photoproduction on the Proton(Heimberg, Berman, Briscoe) We have spent considerable effort on the analysis of the p0 channel for the g1b running period. Figure 1 shows a sample (2% of the g1b data) of the differential cross sections obtained. The evolution of the differential cross section is well reproduced by SAID in the region where there is strong experimental data to constrain the fit (up to 1.2 GeV). Even up to 1.7 GeV, the agreement is good. In extracting these differential cross sections, cuts on missing mass, acceptance boundaries, and proton momentum were applied. The combined effect of such cuts is to remove about 10% of the yield and is accounted for in the simulation.
Figure 1. Differential cross sections from the analysis of the g1b data [Hei01], compared with those of the SAID partial-wave analysis. Exploiting the fact that the SAID fit does a reasonable job of reproducing the shape of the angular distributions, the total cross section is obtained by scaling the SAID total cross section by the ratio of CLAS/SAID cross sections integrated over the acceptance. This result is shown in Fig. 2. The presence of the P33, D13, F15, and F37 baryon resonances is nicely reproduced. In all cross-section plots, the uncertainties are statistical only. The systematic uncertainty is, for this analysis, estimated to be about 7%, with the major contributors being uncertainties in proton detection efficiency and photon flux (about 4% each). These results were shown at the 2001 International Nuclear Physics Conference [Hei01].
Figure 2. Total cross section for the gp ® pop reaction. |
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