View source for Compton Photon Detector Centering Procedure

= Spring 2019 Compton Photon Detector Commissioning =
* Before MCC begins the initial process of passing bream through the Chicane, we must:
*# Check and set HV:
*#* PhDet HV -> '''OFF'''
*#* Side (V) and Top (H) Finger Scintillator -> '''ON'''
*#* Laser table scintillators -> '''ON'''
*# The following EPICS channels may be useful to monitor the backgrounds
*#* ComptonUSbg1
*#* ComptonUSbg2 <-- May not be updating on EPICS/StripTools yet
*#* ComptonDSbg1
*#* ComptonDSbg2
*# The following EPICS values may also be useful
*#* hac_bcm_average
*#* IPM1P02A.XPOS
*#* IPM1P02A.YPOS
*#* IPM1P02B.XPOS
*#* IPM1P02B.YPOS
*#* Optionally the two finger scintillators may be useful, though it's likely they won't see anything if they are behind the collimator
*#** ComptonHfingerRate
*#** ComptonVfingerRate
*# It may be useful to take a run during this period. Even though the HV on the detector is off, we may use it to study noise on the system.

* After the beam is stable in the chicane and ready to center beam on laser
*# Check and set HV:
*#* PhDet HV -> '''ON'''
*#* Side (V) and Top (H) Finger Scintillator -> '''ON'''
*# Start a Compton Run (though, no need to analyze the run right now, this will just help us commission and calibrate the DAQ later)
*# With the laser ON and '''not flipping'', monitor the following EPICS channels:
*#* IPM1P02A.YPOS
*#* IPM1P02B.YPOS
*#* ComptonCentralRate
*#* ComptonCentralRateHigh
*#* COMPTON_PW1PCAV_ca
*# As the beam is scanned vertically monitor for spikes in ComptonCentralRate and ComptonCentralRateHigh.
*#* The goal is to maximize ComptonCentralRate (assuming stable beam and laser power) and record the vertical position
*#* Ideally we would like the slope between BPM 02A and 02B to be as close to zero as possible

* After the beam is centered on the laser, ask MCC to lock the beam in the optimal position found previously and then begin the detector centering procedure
*# Check and make sure all HV Compton channels [[HV_Control_GUI]] are '''ON''' (should have been done by steps above, so just confirm nothing has tripped off)
*# Start a new run
*# Center the detector vertically ('''Note: do not lower the table to 0, always keep it above 0 mm)
*## Set the Photon Detector table to X=69.00 mm, Y=6.00 mm
*## Monitor EPICS channels:
*##* ComptonHfingerRate <-- looking for a maximum/peak on this when scanning table position
*##* COM_DETPH_YCPOSai
*##* ComptonCentralRate <-- possibly should see a minimum on this channel
*##* ComptonCentralRateHigh <-- possibly should see a minimum on this channel
*## Then in 0.5 mm increments scan Y from 6.00 to 16.00 mm (~2-3 seconds at a time is enough)
*## Once a rough idea of where the max was, scan a range in as small increments as possible with a +/- 2mm range
*## Once you confirm the optimal y-position that gives maximum ComptonHfingerRate maximum (and minimum on ComptonCentralRate and ComptonCentralRate) , then move the table up by 20 mm from this position.

*# Center the detector horizontally ('''Note: do not lower the table to 0, always keep it above 0 mm)
*## Set the Photon Detector table to X=44.00 mm, Y=<value from step above>
*## Monitor EPICS channels:
*##* ComptonVfingerRate <-- looking for a maximum/peak on this when scanning table position
*##* COM_DETPH_XCPOSai
*##* ComptonCentralRate <-- possibly should see a minimum on this channel
*##* ComptonCentralRateHigh <-- possibly should see a minimum on this channel
*## Then in 0.5 mm increments scan Y from 44.00 to 54.00 mm (~2-3 seconds at a time is enough)
*## Once a rough idea of where the max was, scan a range in as small increments as possible with a +/- 2mm range
*## Once you confirm the optimal y-position that gives maximum ComptonVfingerRate maximum (and minimum on ComptonCentralRate and ComptonCentralRate) , then move the table in +x direction by 20 mm from this position.