Absolute & Relative Normalization

1. Absolute & Relative Normalization Paul E. Reimer 8 January 2009 Luminosity monitors Calibrations Targets composition Based on Theses of R. Towell and J. Webb

2. Luminosity and Beam Monitors • Secondary emission monitors (SEM) • Primary beam intensity monitor • Ion chamber (IC) • Secondary monitor • Segmented wire ion chamber (SWIC) • Position and profile monitor • Scintillator telescopes (AMON, WMON) • Viewed targets at 85o in lab through hole in shielding • Absolute calibrations? Paul E. Reimer Absolute and Relative Normalization

3. SEM vs. IC3 Approx. 2000 SEM • Not quite linear • Calibration and/or offset changes during dataset • Affects all targets in the same way. • Shifts can be isolated to particular times/jumps • Not significant problem for Ratio experiment Linear relationship Deuterium (ic3+0) Empty (ic3+2.5e4) Hydrogen (ic3+5e4) Paul E. Reimer Absolute and Relative Normalization

4. SEM linearity check • Plot sem vs. other luminosity monitors (amon and wmon) • Perform similar test with IC3 Deuterium Empty Hydrogen Paul E. Reimer Absolute and Relative Normalization

5. SEM Offset empirically determined • Should also be examined target-by-target Paul E. Reimer Absolute and Relative Normalization

6. SEM absolute calibration • Difficult—6.5% systematic uncertainty for E866/NuSea • Replace target with thin Cu foil • Proton beam activates Cu foil creating 24Na • Measure rate of 1368 keV ’s emitted by the 24Na • Need 24Na production cross section • Measured at 400 GeV, not 120 or 800 GeV • 3.90 ± 0.11 mb (2.7% uncertainty already) • Can we do better???? Historic calibration data for MEast beam line Paul E. Reimer Absolute and Relative Normalization

7. Target issues • Target Length • Measure it—Write it down—Note which target it belongs to. • Target Density from target measured target pressure (see ref. in Webb’s thesis) • Similar formula for deuterium • Approx. 2% systematic for E866/NuSea • Target attenuation length • PDG values for H2 and D2 • Also need HD for lD2 contamination Paul E. Reimer Absolute and Relative Normalization

8. Target Contamination • Analysis of D2 gas during fill done at Argonne (black box) • Approx 1% uncertainty in Absolute Luminosity • Approx 0.61% uncertainty in Ratio • Tied with rate dependence for largest uncertainty Paul E. Reimer Absolute and Relative Normalization

9. Conclusion • Relative uncertainty dominated by target composition • Obtain purest D2 we can get from Fermilab • Absolute uncertainty dominated by SEM calibration • Better ideas?? Paul E. Reimer Absolute and Relative Normalization