Beam startup/recovery Procedure:
This procedure is required for short period of absence of beam (and no major accelerator work).
- Beam energy lock: ON Hall A.
- Fast feedback lock: ON
- Target: start from empty or BeO as needed.
- Beam entrance and exit window cover OUT (if there were an access).
- Beam tune, either straight or through Compton chicane (use the same setting as before).
- Make sure BPM A and B readings are at the nominal position (see whiteboard).
- (?) Verify settings of target Ion chamber trip limit (MCC with Radcon).
- Ask for harp scan, require that beam $\sigma_x$: 100 - 300microns, $\sigma_y$:100 - 300microns on two hall A harps.
- Move target to holey carbon, use 2microA and 6x6 MCC units raster size (3x3mm2
at target). Take a short spectrometer run. Do spot++ (halog the plots),
make sure the carbon hole is centered (halog it). To see a better hole,
can use only T1 triggers and prescale away all physics triggers.
- Move target to LD2. Use 2microA, do the following raster scan:
- start from 2 x 2 (MCC units) raster (1x1mm2 at target), run spot++ to confirm raster size, and record trigger rates;
- increase to 4x4 (MCC units) raster (2x2mm2 at target), run spot++ to confirm raster size, and record trigger rates;
- increase to 6x6 (MCC units) raster (3x3mm2 at target), run spot++ to confirm raster size, and record trigger rates;
- If rates go a
dramatically high value, the beam has hit the target wall. Stop immediately and consult the run coordinator.
- If the rate on each raster size is the same in above 3 steps, we
can take beam for commissioning (or production). Ask for the raster
size so as to get the beam of size 3 mm x 3 mm on target (6x6 MCC unit).
- Check signals from lumi-monitors, beam position monitors, beam charge monitors.
- Lumi readings can be clearly lined up with real triggers in time? Fast clock serves as a time mark.
- Check Happex beam charge feedback check.
- Make sure the VDC high voltage is OFF.
- If in production mode, run both spectrometer CODA and PVDIS/HAPPEX CODA:
- For spectrometer CODA, monitor the deadtime. Use proper prescale factors to limit the deadtime.
- For both CODA, run online analysis and check data with sample histograms.