Special Procedures for Modified Beamline
From APEXwiki
The procedures below include both commissioning for the permanent magnet and standard operating procedures.
Contents |
Beamline Commissioning
(to be done Friday day shift)
- As soon as accelerator is ready to deliver beam and target cool-down is complete, contact MCC to initiate the beamline commissioning procedure below (phase 3 of the beamline commissioning procedure detailed in PHY/10-006-TOSP). One person on shift (preferably SL) should go to MCC and start Hall A Tools on a computer there, to control septum. Make sure regulation of the spectrometer magnets is off, so that only septum field is being varied. Scroll down or click here for the list of setpoints that should be defined.
Setpoints
We have established 3 setpoints (MCC will probably refer to them by the 2nd column, septum current). Almost all the time we will use the highest of the settings, 775.6 A / 1.131 GeV.
| Setpoint | Septum p (GeV/c) | Septum I (A) | Corrector I (A) |
|---|---|---|---|
| Alpha | 0.7 GeV/c (60%) | 480.0 A | -4 A |
| Bravo | 0.9 GeV (80%) | 617.2 A | +1 A |
| Charlie | 1.131 GeV (100%) | 775.6 A | +9 A |
Coarse Beam Alignment Procedure
- DAQ configuration - Left Arm
- Prescale T8 (kHz pulser) = 1, everything else 100000
- Empty target - 5 uA no raster. Do harp scans, size should be between 100 um and 300 um
- Empty Target - 5 uA, raster on
- Start with MCC raster units 4x4
- Take run and do spot++ and adjust MCC units to get 6x4mm^2 spot
- Note raster MCC units on whiteboard
- BeO target, 5 uA, raster on
- Ask for
BPM4A(X,Y) = (0,0)
BPM4B(X,Y) = (0,0)
- Do BeO to get visual spot
- Have MCC adjust BPMs accordingly to get spot reasonably centered on target
Fine Beam Alignment Procedure
- DAQ Configuration: Left arm only
- Prescale: T1 (S2m) = 1, everything else 100000
- Trigger rates should be nominally few kHz
- Carbon Hole Target, 5 uA, raster on
- Take run and do spot++
- Adjust BPMs such that the carbon hole is centered
- Note BPMs on whiteboard and in HALOG
- Pb/Diamond #1, 0.5 uA, raster on
- Take run and do spot++, make sure not hitting the frame
- Ask for raster 8x8mm^2 (scale from MCC units accordingly)
- Take run and do spot++, make sure still not hitting the frame
- Go back to previous raster size.
Magnet Heating Test, Part I
- Make sure a stripchart is configured to track the readout of thermocouples on the permanent magnet (note that these channels cannot be accessed from the TO computer; they are accessible from the SL computer):
HacB_HPE1313A:0_Ch22 HacB_HPE1313A:0_Ch23
- (Note: one of these channels appears to be broken.)
- With 1uA current, establish 6mm x 4mm raster on Carbon target, make sure we are not hitting frame (should be determined by alignment procedure)
- Move to Pb/C target #1 (assuming target has been cooled), check with spot++ that beam is still not hitting frame.
- Record initial permanent magnet temperature
- Request 5uA and monitor change in magnet temperature.
- Watch the magnet thermocouple EPICS channels; when temperature has risen 10 degrees or after 20 minutes (whichever comes first), record
- Duration of run
- Initial and final permanent magnet temperature
- Strip chart
- to HALOG, and terminate the test. We expect that temperature should rise slower than 40 degrees C per hour (this is higher than the number in TOSP, which assumed thinner APEX W/Ta target).
- Contact RC to determine whether to proceed to Part II or postpone Part II for access.
- Go to empty target, and using the dump viewer (MCC), check the beam position to verify the stability of the PM field integral.
Magnet Heating Test, Part II
- Move to Pb/C target #1 (remember to call MCC to mask/unmask FSD node)
- Make sure MCC re-establishes 6mm x 4mm raster, and increase beam current to 30 uA.
- Monitor (and record in HALOG) the rise of the permanent magnet temperature, using the thermocouple channels listed above:
- When the temperature has reached 70 deg C:
- Ask MCC to stop beam
- Move to empty target (remember to call MCC to mask/unmask FSD node)
- Post stripchart into HALOG.
- Ask MCC to turn on beam again, view beam spot in dump viewer
- Move back to Pb/C #1 target (remember to call MCC to mask/unmask FSD node)
- Please call Natalia -- I want to look at the strip charts once they're on HALOG.
- Resume 30 uA beam with 6x4 mm raster on Pb/C #1
- Repeat the above at 120 deg C (if temperature appears to be leveling out at a temperature below 120, repeat this step when thermocouple reaches about 80% of anticipated limiting temperature).
- When the temperature has reached 70 deg C:
- With beam off, monitor (and HALOG) rate at which the permanent magnet cools down.
Production with Modified Beamline (IMPORTANT!)
Changing septum central momentum
If you change the septum momentum without, you must coordinate with MCC! Otherwise, it will trip an FSD node. The procedure is similar to moving the target:
- Call MCC, tell them you want to change the septum current and inform them of the new setpoint (see list).
- They will need to mask an FSD node before you adjust the septum central momentum.
- Call MCC again when the septum current has reached its stable value. Confirm with them that they have switched the corrector magnet to the proper setting.
Monitoring Magnet During Production
- Every 3 hours during production, you must request a check of the beam-spot on dump from MCC:
- Call MCC to turn off beam, mask target FSD node and request a beam spot check.
- Move target to empty, call MCC when complete
- MCC will send beam through hall to check dump viewer, will call back to let us know beam spot is ok.
- Request FSD mask on target to move back to previous position.
- Request beam again, making sure to re-establish same raster as before.
- A "yellow" alarm point (tread carefully and consider lowering current) is at 120 deg C.
- Beam will be shut off if temperature exceeds 150 deg C (We do not want to trip this alarm!).
