Draft Outline for Commissioning

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Review Sequence

  1. Electron beam
    • OSP and small internal review in order to power and map tagger magnet
    • Transfer of tagger magnet operation to accelerator, so that it can be reviewed as part of ARR II (nominally Jan)
  2. Photon beam
    • Review of photon beamline (radiator to photon beam dump). Nominally scheduled for March, at least 3 months prior to beam delivery
    • Items to be covered by this review include:
      1. tagger hodoscope
      2. tagger microscope
      3. profile monitor -- where does this go? (not considered by Photon Beam WG so far)
      4. active collimator
      5. halo monitors
      6. other photon beam monitors -- pair spectrometer? total absorption counter?
  3. Experimental Equipment Hall D
    • Experimental apparatus in Hall D (prior to use with beam)

Equipment List

Commissioning Bullets GlueX-doc-2363

Electron beam

Goals

  1. Safely deliver electron beam to the electron beam dump [1]

Assumptions

  1. Accelerator has qualified the machine protection system (MPS) and the personnel safety system (PSS) for the tagger building
  2. Assume steel blocks (> 20" thick) are stacked in front of the entrance to the photon beam pipe that connects the tagger hall to Hall D to prevent any direct beam spray from traveling down to Hall D.

Checklist at low current I~1uA, tune mode [2]

  1. Check beam is centered on the beam dump
  2. Scan position of beam over the area of the radiator
  3. Check single rates at various positions in the tagger enclosure (electronic racks)
  4. Check single rates at the location of the tagger microscope
  5. Check single rates at the location of the tagger broad band hodoscope
  6. Verify tagger magnet excitation curve matches predictions, e.g. for different beam energies
  7. Verify controls for all beamline elements work as expected
  8. Check radiation levels in the tagger hall [1]
  1. Establish location in the hall for electronic racks safe from radiation
  2. Identify sources of background (scraping) in the hall.
  3. Check Fast Shutdown system

Checklist at low current I < 100 nA, CW

  1. Verify proper operation of beam as in pulsed mode
  2. Check single rates at various positions in the tagger enclosure (electronic racks)
  3. Check single rates at the location of the tagger microscope
  4. Check single rates at the location of the tagger broad band hodoscope
  5. Identify sources of background (scraping) in the hall.
  6. Check out amorphous ladder controls
  7. Commission halo pmts located on the electron beam pipe to the dump (i.e. adjust HV settings)
  8. Change radiators and check relative thicknesses using halo pmts
  9. Use accelerator harp to determine beam centroid and width
  10. Use amorphous ladder harp to verify beam centroid, width and halo

Checklist at high current I > 2 μA, CW

  1. Verify proper operation of beam as in low current situation
  2. Check single rates at various positions in the tagger enclosure (electronic racks)
  3. Check single rates at the location of the tagger microscope
  4. Check single rates at the location of the tagger broad band hodoscope
  5. Check radiation levels in the tagger hall
  6. Check radiation levels in Hall D
  7. Check radiation levels in the tagger service building

Abnormal conditions

  1. High radiation levels in any or all areas of interest
  2. Accidental loss of power to vertical bend string
  3. Accidental loss of power of tagger magnet
  4. Accidental loss of vacuum
  5. Accidental motion of goniometer target frame into beam

Photon beam

Goals

  1. Determine characteristics of photon beam in Hall D
  2. Safely deliver photon beam through the hall to the photon beam dump

Assumptions

  1. Accelerator has qualified the machine protection system (MPS) and the personnel safety system (PSS) for Hall D and the counting house
  2. Delivery of electron beam through tagger to electron dump has been accomplished
  3. Operation is assumed CW, but perhaps one should start with pulsed mode
  4. Amorphous radiator installed with 10-5 radiation lengths thickness, typical
  5. Steel blocking photon beam pipe in tagger hall has been removed
  6. Initially the solenoidal magnet is off

Notes

  1. We should identify all apertures along the beam line to be aware of possible locations for scraping

Checklist, current I < 100 nA

Location: before active collimator

  1. Require profile monitor to be installed and operational -- where? (cannot be upstream of active collimator)
  2. Require active collimator to be installed and operational
  3. Require halo monitors 1 to be installed and operational upstream of cave exit wall
  4. Check that detector elements in Hall D are off and prepared
  5. Check profile of photon beam exiting the beam pipe into cave
  6. Determine center of photon beam relative to photon beamline
  7. Compare with response of active collimator -- cannot be done with profile monitor installed
  8. Use this exercise to calibrate active collimator response
  9. Scan the electron beam over the face of the radiator to establish aperture and check that photon beam profile behaves as expected
  10. Check feedback signals of active collimator to control system. (Once understood, these can be used in real time to correct the beam position on the collimator).
  11. Study the stability of the beam with and without feedback from the active collimator
  12. Equalize rates in halo counters located in front of the cave back wall
    • Why should these be equal?
    • What are you adjusting to equalize these? (phototube HV? disc. thresh.?)
  13. Check radiation levels inside the collimator cave
  14. Establish possible locations for electronics
  15. Check radiation levels in Hall D
  16. Check radiation levels in the counting house.
  17. Determine suitability of delivering beam into the hall before proceeding.

Location: exiting pair spectrometer

  1. Commission the ladder with the PS converter including the harp
  2. Require halo monitors 2 to be installed and operational downstream of the PS
  3. Perform a harp scan using the converter ladder
  4. Measure intensity and energy distribution of photon beam using pair spectrometer fine and coarse arrays.
  5. Determine rate sensitivity to movements of the electron beam on the radiator
  6. Check radiation levels inside the collimator cave
  7. Check radiation levels inside Hall D
  8. Measure single rates of detectors (e.g. BCAL, FCAL, TOF)

Location: behind FCAL

  1. Relocate profile monitor behind the FCAL? -- this would be a good location for it
  2. Verify expected profile (projection of collimator) through the detector
  3. Verify expected photon beam rate
  4. Check radiation levels inside Hall D
  5. Measure single rates of detectors (e.g. BCAL, FCAL, TOF)

Alignment of beam to target

  1. Install commissioning target and start counter
  2. Check that photon beam is transmitted cleanly through target cell
  3. Use start counter rates to verify the photon beam is centered on the target
  4. Check singles rates of detectors (e.g. BCAL, FCAL, TOF)

References

  1. ↑ 1.0 1.1 Abkemeier, E. et al., "Shielding Basis for hall D Complex," July 2008, JLAB-TN-08-033
  2. ↑ Freyberger, A. and Tiefenback, M., "Diagnostic Specifications for the 12 Gev Upgrade," 2007, JLAB-TN-07-022
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