Luminosity Monitoring For PrimEx

Dan DalePrimEx Collaboration Meeting

February 23, 2007

E.P. point 14

• “Electron counting systematics listed as 0.8%. How did you get this number?”

Electron Counting Systematics0.8% discrepancy between CLOCK and OUT-OF-TIME methods

E.P. point 15

• “You discuss in the Appendix effects of beam intensity instabilities on rate sampling. You don’t quantify this effect and do not include in final error”

0.8% discrepancy between CLOCK and OUT-OF-TIME methods

CLOCK trigger sampling used -> insensitive to beam instabilities

Point 11:Clock frequency, window width

• Ne = ne / (W x ntrigs) Live1

• Clock frequency = 195.3125 +-0.020 kHz• W = 7 microseconds –

integral linearity < 25 ppm differential linearity 100 psec

DS point: Different PS dipole settings--run 4339 collimator 0.1 “

off

Effect of Collimator Position on Tagging Ratios

Effect of Collimator Position on Tagging Ratios – units are inches

TAC losses

0.1% interact in vacuum window & Helium – overwhelmingly pair production

Point 13: “Section 25 all numbers in two tables identical except last one.

Something is not right”

Luminosity Error Budget________________________________________effect error(%)Uncorrected leakage current 0.5 (1.4%/3) TAC statistics 0.2 (0.5 per T channel)Electron counting systematics 0.8 (clock versus out of time)Electron counting statistics negligibleTAC reproducibility 0.4HYCAL collimation of TAC 0.25 (worst case, no photon collimator)Beam position/collimator effect 0.2Absorption in TAC runs not yet evaluated_______________________________________________________________

1.1%

What we can ultimately do.

Luminosity Error Budget________________________________________effect error(%)Corrected leakage current 0.3 (1.4%/3/2) TAC statistics 0.2 (0.5 per T channel)electron counting systematics 0.8 (clock versus out of time)Electron counting statistics negligibleTAC reproducibility 0.4HYCAL collimation of TAC 0.25 (worst case, no photon collimator)Beam position/collimator effect 0.2Absorption in TAC runs not yet evaluated_______________________________________________________________

1.0%

• Points 1,3: “Please define meaning of T-counter and T channel”

• Point 2, 16: “In section 4 (2002 run analysis) just T counters used. E-T coincides since implemented. Needs to be written up.

• Point 5: absolute efficiency of TAC – dedicated run????