1. Luminosity Monitoring For PrimEx Dan Dale PrimEx Collaboration Meeting December 16, 2006

2. Conclusion 1: What we have now Luminosity Error Budget ________________________________________ effect error(%) Uncorrected leakage current0.5 (1.4%/3) TAC statistics0.2 (0.5 per T channel) Electron counting systematics0.8 (clock versus out of time) Electron counting statisticsnegligible TAC reproducibility0.4 HYCAL collimation of TAC 0.25 (worst case, no photon collimator) Beam position/collimator effect0.2 Absorption in TAC runsnot yet evaluated _______________________________________________________________ 1.1%

3. Beam leakage from other Halls If not corrected: ~1.4% effect on 1/3 of runs = 0.5% error

4. TAC Statistics +- 0.5% per T channel If we combine all  0.2% Electron Counting Systematics 0.8% discrepancy between CLOCK and OUT-OF-TIME methods Electron Counting Statistics Negligible.

5. Dependence of Tagging Ratios on Beam Intensity

7. Effect of Photon Beam Collimator

9. Effect of Collimator Position on Tagging Ratios

11. Effect of Beam Missteering on Tagging Ratios Run 4338: centered Run 4340: 5mm up Run 4341: 5.7 mm X 0.22mm Y Run 4342: 8.62 X Run 4343: 6 mm X

12. Short Term Stability of Tagging Ratios – Consecutive Runs

14. Long Term Stability of Tagging Ratios

16. Dependence of Relative Tagging Ratios on Rate

17. Conclusion 2: What we can ultimately do. Luminosity Error Budget ________________________________________ effect error(%) Corrected leakage current0.3 (1.4%/3/2) TAC statistics0.2 (0.5 per T channel) electron counting systematics0.8 (clock versus out of time) Electron counting statistics negligible TAC reproducibility0.4 HYCAL collimation of TAC 0.25 (worst case, no photon collimator) Beam position/collimator effect0.2 Absorption in TAC runsnot yet evaluated _______________________________________________________________ 1.0%