Bullseye scans

From PREX Wiki
Revision as of 02:49, 21 June 2019 by Sanghwa (Talk | contribs)

Jump to: navigation, search

In the process of editing and updating this page. Please contact Juliette Mammei crowder@jlab.org with questions or suggestions.

PREX Main<< HOW TOs << Expert Tools

  • BPM Calibrations (Bullseye Scan, 1-2 hours)
  • BPM pedestal run (20 minutes)

How to perform a bulls eye scan:

1. You need unrastered, stable beam:

    - This must be completed in phase 1! 
    - Target/trigger doesn't matter here. Use clock trigger, adjust PS8 to get high rate
    - run both arms

2. Ask MCC to steer the beam to the nominal center of the target.

3. Wait until beam is stable and have MCC perform a harp scan for the two superharps near the target (1H04A and 1H04B) and take a CODA run for both the left and right spectrometers during the same time. Start the coda run first before asking MCC. Request MCC to make an ELOG entry with the Harp results, you should see all three harp wires. Record ELOG entry numbers and timestamps of both harpscans. Take each run for ~50k events.

You can bring the harp fitter up from JMenu (JMenu  > Operations > Harps > Harp Fitter Tool)
Left top corner menu > Harp Selection > HALL A

4. Ask MCC then to steer the beam to positions around the nominal center:

    - cover at least the area the raster will cover: (2,2), (2,-2), (-2,-2), (-2,2), and repeat (0,0)
    - repeat harp and CODA runs for each position

5. Record Harp scan run numbers and corresponding CODA run number for each beam position. As an example, see HALOG # 3324009.

6. Make a record of the harp scans and CODA runs in the HALOG.

How to analyze the bulls eye scan:

 - detailed instructions can be found at the Analyzing BPMs website.
 - the shift crew is not expected to analyze the bulls eye scan.

BPM pedestal run

  1. Ask MCC to set iocse10 to Forced gain = 0.
  2. Take CODA run for both Right and Left arms.
    • Use only clock triggers. T8=100
    • Need about 100k events.
  3. Ask MCC to set iocse10 to auto gain.
    • can be located at /cs/opshome/edm/bpm/diag_see/IPM_E_GainCntrl.edl

Marathon page