Absolute & Relative Normalization
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Transcript of Absolute & Relative Normalization
Absolute & Relative Normalization
Paul E. Reimer
8 January 2009
1. Luminosity monitors
2. Calibrations
3. Targets composition
Based on Theses of R. Towell and J. Webb
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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?
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SEM vs. IC3
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
Deuterium (ic3+0)
Empty (ic3+2.5e4)
Hydrogen (ic3+5e4)
Linear relationship
Approx. 2000 SEM
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SEM linearity check
Plot sem vs. other luminosity monitors (amon and wmon)
Perform similar test with IC3
Deuterium
Empty
Hydrogen
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SEM Offset empirically determined
Should also be examined target-by-target
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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????
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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
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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
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Conclusion
Relative uncertainty dominated by target composition
– Obtain purest D2 we can get from Fermilab
Absolute uncertainty dominated by SEM calibration
– Better ideas??