The CES and CPR are two main methods for calculating the photon cross section. Ideally, both methods should give the same cross section. In Run 1a the two cross sections agreed to 2%. Originally, the neither the 1b or 630 GeV cross sections agreed. We recalibrated the background efficiencies for the two methods using pi0's from charged rho decays. We discovered that there was a significant discrepancy between the measured and expected CPR and CES pion efficiencies. We applied the recalibrated efficiencies to the CES and CPR cross sections to both data sets and the CES and CPR methods were brought together.

At the time the 1b and 630 GeV photon cross sections were blessed there were several things left to do in our analysis. The main things were recalibrating the signal efficiencies using the photons from eta decays, measuring the trigger efficiencies, applying lateral shower leakage corrections, finding the source of the discrepancy between the measured and expected CPR and CES efficiencies, and calculating the CPR and CES systematic errors. This talk will just deal with the eta analysis and the trigger efficiencies.

The eta analysis was virtually identical to the one done in Run 1a. The main differences involved switching from a 6 GeV photon trigger to a 10 GeV photon trigger, changing the size of the isolation cone, and switching to 11 channel clustering. We found nice eta peak and tried to measure the CPR efficiency for the etas. We had to do a statistical background subtraction, but the background efficiency was different on each side of the eta peak. Therefore, the error on the eta CPR efficiency was the same magnitude as the discrepancy found in the rho analysis. The eta's could not be used to correct the photon efficiencies.

There were 3 triggers used in the 1b photon cross section: 10 GeV isolated, 23 GeV isolated, and 50 GeV non-isolated. There were four main components of the triggers that needed to be studied: Pt turn on, isolation, XCES, and HAD/EM. The first three components were studied independently for each trigger and the last was taken from CDF3120. The Pt turn on was measured by finding the fraction of events from a trigger with a lower Pt threshold also passed the trigger of interest. The isolation was found by calculating the fraction of events from the non-isolated 10 and 23 GeV trigger samples that passed the neural net isolation cut. The XCES efficiency was taken from the 23 GeV Pt turn on curve. The final efficiencies ranged from 0.611 at low Pt to 0.99 at high Pt.