Tune Photon Beam
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Tune Electron Beam
Tune Photon Beam
- Goal: Tune the photon beam to go through the collimator, the experimental target area, and into the photon beam dump.
- Schedule: Start Oct 10 2014, 4 days
- Responsibility: HallD, Accelerator, RadCon.
- Priority: Most activities are High, but includes Moderate and Low priority activities.
- Prerequisites:
- Hall D: Detectors turned off. Exceptions: Profiler, possible BCAL, outer rings of the FCAL
- Collimator: blocking position (similar to the electron beam tune phase). The motion must be calibrated.
- Profiler installed in the Collimator Cave, surveyed in order to find the position of the nominal beam center
- Pair spectrometer field on, converter retracted.
- Solenoid on with current ~300A.
- No target in place (air and material along the beamline makes a few R.L.).
- Activities
- (High) Re-establish the CW electron beam 50 nA to the Tagger Dump (Accelerator)
- (High) Insert the 1.7·10-5 R.L. and check the radiation levels in the Tagger Hall and the Collimator Cave (Hall D/Accelerator)
- (High) Using the Profiler find the beam center position with respect to the nominal position (Hall D)
- (High) MCC moves the beam to the nominal position, separately in 2 projection, using the last corrector. Calibrate the predicted position vs the position provided by the Profiler. (Hall D/Accelerator)
- (High) Check the electron beam position at the Dump using the second Beam Profiler (Hall D/Accelerator)
- (High) Move the collimator 5 mm hole in X, ±30 mm around the center in order to calibrate the Active Collimator X-response. Leave the collimator in the nominal position (0.5 mm hole at the nominal center) (Hall D)
- (Moderate) If the Active Collimator data provides a better position accuracy - move the beam in X accordingly (Hall D/Accelerator)
- (Moderate) Request an access, rotate the Active collimator by 90 degree. (Hall D). Time estimate: 2h? (get into Hall: 30 min, rotate collimator 5min, leave and close the Hall, 30 min. Restore beam: 10min. What else?)
- (Moderate) Move the collimator 5 mm hole in X, ±30 mm to calibrate the Active Collimator Y-response. Leave the collimator in the nominal position (0.5 mm hole at the nominal center) (Hall D)
- (Moderate) If the Active Collimator data provides a better position accuracy - move the beam in Y accordingly (Hall D/Accelerator)
- (High) Move the beam in X ±10 mm around center, verify the Active Collimator response (Hall D/Accelerator)
- (High) Move the beam in Y ±10 mm around center, calibrate the Active Collimator response (Hall D/Accelerator)
- (Moderate) If the Active Collimator data provides a better position accuracy - move the beam in Y accordingly (Hall D/Accelerator)
- (High) Install a PS foil converter, turn on the low-granularity PS counters, measure the coincidence rate of two arms (Hall D)
- (High) Using the PS wire scanner and the PS coincidence rate measure the position of the beam spot at the converter (Hall D)
- (High) Insert a PS foil converter, turn the PS detectors on and start taking data - keep the PS running (Hall D)
- (High) Control access: move the Profiler to the location in front of the Solenoid (Hall D)
- (High) Re-establish the beam and measure the position at the Profiler (Hall D)
- (High) Control access: move the Profiler to the location in front of the Photon Beam Dump (Hall D)
- (High) Re-establish the beam and measure the position at the Profiler (Hall D)
- (High) Compare the beam position measurements. Consider moving the collimator from the nominal position if deviations of >5 mm are observed (Hall D)
- (High) Re-calibrate the Active Collimator in X (use the slide) and Y, without the Profiler in front (Hall D)
- (High) Turn on the Start Counter (ST). Check the rate asymmetry (Hall D)
- (Moderate) Move the collimator ±10mm and check the rates on the ST (Hall D)
- (High) Set the solenoid current to 1000 A (Hall D)
- (High) Turn on the detectors one by one from the periphery to the center monitoring the rates without and with the beam (Hall D)
- (High) Control Access: install the cup target (2mm and 7mm thick) into the central position in Z (Hall D)
- (High) Re-establish beam (Accelerator)
- (High) Verify the standard BCAL vs FCAL trigger (timing and thresholds) - about 4h (Hall D)
- (High) Take 1 shift of data (Hall D)
- (Medium) Measure the rates and radiation levels with the 11·10-5 R.L. radiator