Photon Beam Design Requirements

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Revision as of 16:20, 29 January 2008 by Jonesrt (Talk | contribs) (Global Specifications for the Hall D Photon Beam)

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Global Specifications for the Hall D Photon Beam

  1. choice of photon energy in the range 8 - 12 GeV [1]
  2. duty factor >90% at 500 MHz beam pulse repetition rate [1]
  3. orientable diamond crystal bremsstrahlung radiator [2]
  4. peak linear polarization of 40% at 9 GeV with collimation [2,3]
  5. average polarization 36% in coherent peak 8.4 - 9.0 GeV [2,3]
  6. photon beam collimator with half-angle 22 μr [3]
  7. photon beam centered on collimator to within 3 μr [3]
  8. photons tagged with energy resolution better than 60 MeV (0.5%) within coherent peak [1,4,5]
  9. beam tagged with reduced resolution over extended range 3.0 - 11.4 GeV [4,6]
  10. complete tagger coverage in range 9.0 - 11.4 GeV with 1% resolution [6]
  11. absolute photon energy calibration better than ±30 MeV
  12. nominal operation at 10 MHz tagged photons in coherent peak after collimator [1,3]
  13. tagging rate 25 MHz within coherent peak at nominal intensity [5]
  14. tagger capable of operating at intensities up to 100 MHz in coherent peak after collimator [1,3,5]
  15. beam adjustable down to threshold of 0.1% nominal intensity for absolute normalization [6]
  16. continuous real-time monitoring of post-collimator beam spectrum [7]
  17. average tagging efficiency at least 50% in the coherent peak under nominal conditions [3,4]
  18. average polarization within coherent peak determined with accuracy ±2% absolute [7]