Difference between revisions of "Photon Beam Design Requirements"
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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. | 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. | ||
− | # choice of photon energy in the range | + | # choice of photon energy in the range 6 - 12 GeV [1] |
# duty factor >90% at 500 MHz beam pulse repetition rate [1] | # duty factor >90% at 500 MHz beam pulse repetition rate [1] | ||
− | # orientable diamond crystal bremsstrahlung radiator [2] | + | # orientable diamond crystal bremsstrahlung radiator [2,3] |
− | # peak linear polarization of 40% at 9 GeV with collimation [2,3] | + | # peak linear polarization of 40% at 9 GeV with collimation [2,3,4] |
− | # average polarization 36% in coherent peak 8.4 - 9.0 GeV [2,3] | + | # average polarization 36% in coherent peak 8.4 - 9.0 GeV [2,3,4] |
− | # photon beam collimator with half-angle 22 μr [ | + | # photon beam collimator with half-angle 22 μr [4] |
− | # photon beam centered on collimator to within 3 μr [1, | + | # photon beam centered on collimator to within 3 μr [1,4] |
− | # photons tagged with energy resolution better than 60 MeV | + | # photons tagged with energy resolution better than 60 MeV within coherent peak [1,5,6] |
− | # beam tagged with reduced resolution over extended range 3.0 - 11. | + | # beam tagged with reduced resolution over extended range 3.0 - 11.7 GeV [5,7] |
− | # complete tagger coverage in range 9.0 - 11. | + | # complete tagger coverage in range 9.0 - 11.7 GeV [5,7] |
− | # nominal operation at | + | # sampled tagger coverage in range 3.0 - 9.0 GeV [5,7] |
− | # tagging rate | + | # nominal operation at 100 MHz tagged photons in coherent peak after collimator [1,5,6] |
− | + | # tagging rate 250 MHz within coherent peak at nominal intensity [6] | |
− | # beam adjustable down to threshold of 10<sup>-4</sup> nominal intensity for absolute normalization measurements [1, | + | # beam adjustable down to threshold of 10<sup>-4</sup> nominal intensity for absolute normalization measurements [1,8] |
− | # average tagging efficiency at least | + | # average tagging efficiency at least 70% within coherent peak under nominal conditions [1,5,6] |
− | # continuous real-time monitoring of post-collimator beam spectrum [ | + | # continuous real-time monitoring of the post-collimator beam intensity spectrum with energy resolution better than 60 MeV over range 6.0 - 12.4 GeV [9,10] |
− | # average polarization within coherent peak determined with accuracy ± | + | # average polarization within coherent peak determined with accuracy ±1% absolute [9,10] |
− | # absolute tagged photon energy calibration better than ±30 MeV [ | + | # absolute tagged photon energy calibration better than ±30 MeV [9,10] |
− | # 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 [ | + | # 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 [11] |
== Photon Beam Subsystems == | == Photon Beam Subsystems == | ||
− | # 12 GeV electron beam and associated instrumentation | + | # [[Specification for 12 GeV electron beam and associated instrumentation|12 GeV electron beam and associated instrumentation]] |
− | # diamond radiator | + | # [[Specification for diamond crystal radiator|diamond crystal radiator]] |
− | # active photon collimator system | + | # [[Specification for goniometer mount for radiators|goniometer mount for radiators]] |
− | # tagging magnetic spectrometer | + | # [[Specification for active photon collimator system|active photon collimator system]] |
− | # high-resolution tagging microscope | + | # [[Specification for tagging magnetic spectrometer|tagging magnetic spectrometer]] |
− | # broad-band tagging hodoscope | + | # [[Specification for high-resolution tagging microscope|high-resolution tagging microscope]] |
− | # total absorption counter | + | # [[Specification for broad-band tagging hodoscope|broad-band tagging hodoscope]] |
− | # pair spectrometer and hodoscopes | + | # [[Specification for total absorption counter|total absorption counter]] |
− | # collimator | + | # [[Specification for pair spectrometer and target|pair spectrometer and target]] |
+ | # [[Specification for pair spectrometer hodoscopes|pair spectrometer hodoscopes]] | ||
+ | # [[Specification for post-collimator beamline and shielding|post-collimator beamline and shielding]] |
Latest revision as of 11:38, 8 February 2013
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.
- choice of photon energy in the range 6 - 12 GeV [1]
- duty factor >90% at 500 MHz beam pulse repetition rate [1]
- orientable diamond crystal bremsstrahlung radiator [2,3]
- peak linear polarization of 40% at 9 GeV with collimation [2,3,4]
- average polarization 36% in coherent peak 8.4 - 9.0 GeV [2,3,4]
- photon beam collimator with half-angle 22 μr [4]
- photon beam centered on collimator to within 3 μr [1,4]
- photons tagged with energy resolution better than 60 MeV within coherent peak [1,5,6]
- beam tagged with reduced resolution over extended range 3.0 - 11.7 GeV [5,7]
- complete tagger coverage in range 9.0 - 11.7 GeV [5,7]
- sampled tagger coverage in range 3.0 - 9.0 GeV [5,7]
- nominal operation at 100 MHz tagged photons in coherent peak after collimator [1,5,6]
- tagging rate 250 MHz within coherent peak at nominal intensity [6]
- beam adjustable down to threshold of 10-4 nominal intensity for absolute normalization measurements [1,8]
- average tagging efficiency at least 70% within coherent peak under nominal conditions [1,5,6]
- continuous real-time monitoring of the post-collimator beam intensity spectrum with energy resolution better than 60 MeV over range 6.0 - 12.4 GeV [9,10]
- average polarization within coherent peak determined with accuracy ±1% absolute [9,10]
- absolute tagged photon energy calibration better than ±30 MeV [9,10]
- 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 [11]
Photon Beam Subsystems
- 12 GeV electron beam and associated instrumentation
- diamond crystal radiator
- goniometer mount for radiators
- active photon collimator system
- tagging magnetic spectrometer
- high-resolution tagging microscope
- broad-band tagging hodoscope
- total absorption counter
- pair spectrometer and target
- pair spectrometer hodoscopes
- post-collimator beamline and shielding