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Luminosity Analysis Plan & Status

Detailed analysis and status report on electron counting, pair spectrometer, TAC, target thickness, and cross sections. Includes plans for resolving discrepancies and studying beam effects.

madonna-finley
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Luminosity Analysis Plan & Status

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  1. Luminosity Analysis Plan & Status PrimEx Friday Meeting October 7, 2005 Dan Dale

  2. Analysis efforts • Electron counting (absolute flux) • Pair spectrometer (relative tagging ratios) • TAC (absolute tagging ratios) • Target thickness • Known cross sections (pair production, Compton)

  3. Status of electron counting: • Primary technique: -clock trigger, sample tagger electron rate  essentially done. • Secondary technique: -HYCAL trigger, sample tagger rate out of time with trigger  Deemed lower priority.

  4. Pair Spectrometer Analysis Plan • Stability of relative tagging ratios over time -First pass done for carbon production runs. -Needs to be redone without beam trips. • Study upstream scraping from pair spectrometer and target out runs -done. Looks ok. • Different radiator thicknesses -Does this effect relative tagging ratios/beam profile? -first pass done. No effect detectable. • Study effect of electron-electron bremsstrahlung (radiative Moller) in tagger -Marianna

  5. Stability of relative tagging ratios

  6. Radiator A B B B

  7. TAC Analysis Plan • Resolve discrepancy in tagging ratios obtained by taking 1 versus multiple tagger hits (2% problem). DONE. • Collimator studies: out, 8.6mm 12.7mm -How much are we cutting beam with photon collimator? -What are the downstream consequences of scraping?

  8. TAC Analysis Plan • HYCAL moved around a few mm -How much is HYCAL central hole cutting measured tagging ratios? Relevant runs: 4287 x=4.02 4288 x=0.0, y=+0.49 4289 x=0.0, y=-7.095 4290 x=2.0, y=0.0

  9. TAC Analysis Plan • Collimator moved a few mm left and right -How much are we cutting beam with photon collimator? -What are consequences scraping? (x=-7mm to +8mm) • Beam purposely mis-steered -Impact of beam position on tagging ratios • Pair Spectrometer magnet on, off, low (900 Amps) -Effects of upstream scraping • Consistency check of tagging ratios over time • Effect of beam current on tagging ratios -40-120pAmps (+300 pAmps) • Effect of leakage current (particularly Hall C) on -tagging ratios -electron counting • Target photon absorption • Radiative Moller

  10. *TAC analysis algorithms established and ready to go. *Tagging ratios on a run by run basis being compiled.

  11. Radiative Moller Two concerns: • Energy reconstruction • Flux determination

  12. Radiative Moller and Photon Energy Determination

  13. Radiative Moller and Flux-TAC Investigation Radiative Moller contributes here

  14. Radiative Moller and Flux-Investigation with Pair Spectrometer

  15. Upcoming priorities (1) Finish electron counting, including beam trips. (2) TAC analysis. (3) Pair spectrometer analysis. In parallel: Theoretical calculations of pair, Compton cross sections.

  16. Plans on cross section calculations • Alexandr Korchin (Kharkov) has submitted a calculation plan (available upon request). It includes (1)Bethe-Heitler (modified by nuclear form factor). Ready to program. (2)Virtual Compton scattering. Model under development. (3)Radiative effects. (4)Atomic screening. (5)Electron field pair production.

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