![Page 1: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/1.jpg)
Overview of the GlueX Tagger
and Photon Beamline.
![Page 2: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/2.jpg)
Outline.
• Lay-out of Hall D/GlueX complex.
• Sketch of proposed beamline components.
• Basic beamline monitoring requirements.
• Photon polarimetry.
![Page 3: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/3.jpg)
12 GeV CEBAF
CHL-2CHL-2
Upgrade magnets Upgrade magnets and power and power suppliessupplies
Enhance equipment in Enhance equipment in existing hallsexisting halls
add Hall D (and beam line)
![Page 4: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/4.jpg)
Accelerator East Arc
Hall D Complex
![Page 5: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/5.jpg)
Photon beam and experimental area
Located on the
East side off the
North linac
Tagger BuildingExperimental
Hall D
Solenoid-Based detector
Collimator
Coherent Bremsstrahlung
photon beam
Electron beam
75m
![Page 6: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/6.jpg)
GlueX Beamline
Upstream of Spectrometer (i)
Diamond +Goniometer
Quadrupole
Moveable Microscope 8.5 GeV <Eγ<9GeV
Broadband Focal Plane 3GeV <Eγ<11.4GeV
Electron Beam Current Monitor
Electron Beam Dump
Permanent Magnet
Tagger Dipole Magnet
Moveable Active Photon Monitor
Photon Collimator cave
Concrete Housing
W Collimator
Sweeping Magnet
Steel Absorber
Concrete Block
Ni Collimator
Sweeping Magnet
Steel Absorber
Concrete Block
Moveable Active Photon Monitor
NMR
NMR
Exit Electron Beam (13.4° Bend)
Note.
1. Active Photon monitors-either a scintillating fibre array or a pair camera.
2. Distance from radiator to collimator ~80 m.
Active photon Collimator
Lead wall
Converter
![Page 7: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/7.jpg)
Top View Photon flux Monitor
Magnet
Spectrometer Hall Wall
Detector array
Detector array
Moveable Microstrip Detector
GlueX Beamline
Upstream of Spectrometer (ii)
![Page 8: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/8.jpg)
GlueX Beamline
Downstream of Spectrometer
Moveable Lead Glass Monitor Photon
Beam Dump
Active Photon Monitor
![Page 9: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/9.jpg)
Basic Beamline Monitoring Requirements.
1. The electron beam intensity (current measuring cavity), tagger focal plane counting rate and the collimated photon flux (pair spectrometer) must be maintained at a constant ratio. If any one changes with respect to the others, re-tuning will be necessary.
2. Incident electron beam direction and position (2 cavity position monitors upstream of radiator).
3. Photon beam direction and position ( active collimator, 3 active photon monitors).
4. Absolute photon flux ( lead-glass detector/pair spectrometer).
5. Photon polarisation.
![Page 10: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/10.jpg)
Photon Polarimetry.
It is proposed to measure the photon degree of linear polarisation for ( Hz tagged rate on target measured by the microscope ) by:
a) Indirectly.
• Comparing the shapes of the measured and calculated ratios -diamond /amorphous tagger focal plane spectra – over the complete energy range of the tagger.
• Both the ungated, and gated with photons passing through the collimator, measured focal plane spectra are required.
• The gating signal could come from the pair spectrometer.
• This is one reason why a broad band tagger is necessary.
710
![Page 11: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/11.jpg)
b) Directly.
Various techniques have been studied by Yerevan/Connecticut – 2 papers are in press.
They make 2 recommendations.
• measure the azimuthal distribution of events from nuclear pair production with a Si strip detector triggered by the pair spectrometer, and
• measure hadronic asymmetries - distributions from production – using the GlueX spectrometer.
ee
![Page 12: Overview of the GlueX Tagger and Photon Beamline](https://reader036.vdocuments.us/reader036/viewer/2022062511/5515ca99550346c6278b47a4/html5/thumbnails/12.jpg)
Details of the Photon Beamline and Tagging Spectrometer will be presented in the following
presentations.