Spot++

PREX Main<< Information for Shift Takers << Shift Leader << HOW TOs

1. Purpose: to check the rastered beam size.
2. If you run with T1 trigger and target in place, spot gives a view of the target density.
3. If you run with pulser trigger T8 spot++ gives a view of the rastered spot size.
4. At 20 nA the BPM plots look funny (= no signal)
5. In case 1 or 2 above, the most important plot is on the first page, titled "beam on target y vs x", for example:

https://logbooks.jlab.org/system/temporary/FADC_prex_21079.pdf

How To Run spot++

1. You need to be logged on to the a-onl account
   • ssh –X aonl@aonl2 –l a-onl
2. If part of a Beam Recovery procedure, make sure you have taken a CODA run in counting mode for the LHRS
3. Then type either:
   • spot_L run# for the LHRS (Recommended)

     spot_R run# for the RHRS

   • If no run # is given, analyzes last run taken
4. Plots should pop up after a few seconds
5. When prompted, type y or n to upload the plots to the Elog (or not)

• output file goes to:

/chafs1/work1/spot/

• (For experts) macros, source codes, DB files are at:

/adaqfs/home/a-onl/rastersize/ 

Notes to be incorporated into the above list:

• Need a link to how to run the HRS CODA

• You can get "strange printouts" of errors if you only type spot++ and the last run was for R-HRS, so it's clearer to do what is listed above than to use spot++. (note, this is because spot++ is actually spot_L).

• Hint: Type "spot help" to learn more options.

More Info

What do the plots mean?

Need to put examples of output when we have them

BPMA y vs x: Shows the beam location at BPM A

BPMA x: Shows the number of events at each x value in BPM A

BPMA y: Shows the number of events at each y value in BPM A

BPMB y vs x, BPMB x, BPMB y: Same as above but for BPM B

Beam at target y vs x, …x, …y: Same as above for at the target

BPMA Antenna 1, 2, 3, 4: Signal at the four wires of BPM A, one for X+, X-, Y+, Y-, respectively

BPMB Antenna 1, 2, 3, 4: Same as above but for BPM B

Cavity BCMs

• Low Current running Cavity BCM nominal points
  • The cavities are used in <0.5 uA running territory (for commissioning a lead target with spot ++ check)
• Bob's EPICs variable printing to terminal script:

ssh apar@adaq
~/scripts/showCav.C