How to recover BPM positions after llong beam trip
From Hall A Wiki
Follow this procedure only if beam is down for more than 2 hours or if there are any tune changes (ask MCC if in doubt)
- When beam is back, check to see if the beam positions are back to previous good BPM values.
- Move to 12C (carbon hole) target
- Ask MCC to turn OFF fast raster and tell them you are going to turn ON slow raster (50nA).
- Change slow raster size to 1.4 cm (1.1 volts on function generator)
- Center 12C hole by changing BPMs if necessary
- Do spot_L and spot_3
- X and Y on the spot_L/spot_3 are same as beam except Y axis is reversed.
- Halog all raster plots
- If 12C hole is centered. Note down the BPM values and move to 12C-40 target
- Ask MCC to turn ON fast raster and increase the slow raster size to 2cm (1.45 volts)
- Do spot_L and spot_3
- If beam hits something, then decrease the slow raster size to 1.8cm
- Halog all raster plots
- If raster pattern looks good (no hotspots) on 12C-40 then move to NH3 production target
- Do spot_L and spot_3
- Halog all raster plots
- Check 3rd arm trigger rates. For 2.2 GeV beam with 50nA on NH3 target the rate should be 2-3 KHz and DT < 20%
- If rates on 3rd arm are very high and DT >> 20% , call RC.
- Otherwise you are all set for production!