Beam Commissioning Plan

Electron beam

Goal

1. Safely deliver electron beam to the electron beam dump \cite{shielding}

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 photon beam pipe to the hall to prevent any direct beam spray from traveling down to Hall D.

Objectives at low current I$<$ ?, pulsed mode

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
9. Esablish location in the hall for electronic racks safe from radiation
10. Identify sources of background (scraping) in the hall.
11. Check Fast Shutdown system

Objectives at low current I$<$?, 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

Objectives at high current I$>$?, 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

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 $10^{-5}$ thickness, typical
5. Steel blocking photon beam pipe in tagger hall have 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

Location: before active collimator

1. Require profile monitor to be installed and operational
2. Require active collimator to be installed and operational
3. Require halo monitors 1 to be installed and operational upstream of cave 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
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
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?
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)