Difference between revisions of "Photon Beam Design Requirements"

From GlueXWiki
Jump to: navigation, search
(Global Specifications for the Hall D Photon Beam)
Line 20: Line 20:
 
# continuous real-time monitoring of post-collimator beam spectrum [7]
 
# continuous real-time monitoring of post-collimator beam spectrum [7]
 
# average polarization within coherent peak determined with accuracy ±2% absolute [7]
 
# average polarization within coherent peak determined with accuracy ±2% absolute [7]
 +
# post-collimated beam shielding sufficient to keep detector backgrounds originating outside the experimental target below 1% of those coming from the target seen by all detectors, for each significant particle species considered separately [8]
 +
 +
== Photon Beam Subsystems ==
 +
# 12 GeV electron beam and associated instrumentation
 +
# photon collimation system
 +
#

Revision as of 16:47, 29 January 2008

Global Specifications for the Hall D Photon Beam

The following top-level specifications for the Hall D photon beam are determined by the physics requirements of the GlueX experiment and the anticipated capabilities of the CEBAF accelerator at 12 GeV. The specifications for Hall D beamline components and related instrumentation are derived, in turn, from these. References added to the end of each item in the list below indicate which subsystem is affected.

  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 10-4 nominal intensity for absolute normalization [6]
  16. average tagging efficiency at least 50% within coherent peak under nominal conditions [3,4]
  17. continuous real-time monitoring of post-collimator beam spectrum [7]
  18. average polarization within coherent peak determined with accuracy ±2% absolute [7]
  19. post-collimated beam shielding sufficient to keep detector backgrounds originating outside the experimental target below 1% of those coming from the target seen by all detectors, for each significant particle species considered separately [8]

Photon Beam Subsystems

  1. 12 GeV electron beam and associated instrumentation
  2. photon collimation system