Target density variation check

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Note: Silviu pointed out that word 'density' is not quite right here, it's thickness change unless the target is compressed somehow. I don't know how to change the title of the page, so I am leaving this note.
This thickness change would happen when the diamond get damaged. It would be interesting to check once the target chamber is open.

Pictures of damaged targets: https://prex.jlab.org/DocDB/0004/000428/001/TargetDamage.pdf

Run summary

  • First measurement 09/02/2019
    • Summary plots
    • HALOG summary
    • Target #7 and #10 were checked for current range 5-70uA
    • Septum mistuned on purpose in order to reduce rates, T2 trigger is used
    • Sieve in
    • Clear non-uniformity observed from degraded target (#10) compared to good (still in use) target (#7).
    • More visible at higher current, but hint of similar signature of thickness rearrangement seen at low current.
    • Consistent results from both LHRS and RHRS spot data


  • Second measurement 09/03/2019
    • Summary plots
    • HALOG summary
    • Took high statistics run at very low current (30nA requested), Target #10
    • Septum at nominal setting, no Sieve
    • Similar result shown in RHRS data as previous high current test
    • Different distribution in LHRS is puzzling, might be related to DAQ problem


  • Qsq runs 09/03/2019
    • Summary plots from Qsq runs
    • HALOG run summary
    • 400-500k events for LHRS and RHRS runs during Qsq measurements with various targets (Pb7, 8, 9, 10)
    • Consistency between LHRS and RHRS recovered for target #10
    • Similar signature shown from Target 9 and 10. Target 9 and 10 were used with similar position wrt to collimator center. Later we moved the target ladder horizontally and vertically during repairs while we were running with Target 8. -> This is wrong, target repair happens around July 31 which was even before we started using target #9.
      • Actually the target ladder realignment was done during Target #9 period. (Aug. 7).


useful information

  • Target re-alignment done during PREX2

- July 18 (3mm to left)
- Augusg 7 (2mm to right): while using target #9


Weibn's simulation study

HALOG entry
Simulation check shows that increased thickness in some area of the target resulting increased power to the collimator (and higher effect on radiation). Assuming a donut like shape and factor 2 increase in the thickness in the outer area compared to the center, this brings the collimator power by factor ~3 (compared 1st and 4th row).



How to make plots

  • full replay macro can be found from:
/adaqfs/home/a-onl/sanghwa/stupid_spot/get_rastersize.C
  • To run:
> analyzer -b -q 'get_rastersize.C(run#, first evt, last evt, "outputpath/outputname")'

Example:

> analyzer -b -q 'get_rastersize.C(2293, 1, -1, "rootfiles/L2293.root")'
  • To draw raster current xy distribution:
    • /adaqfs/home/a-onl/sanghwa/stupid_spot/make_2D.C
> root -b
> .L make_2D.C
> plot_all("dyn_therm.list")
This will create dyn_dens.pdf. To open:
> evince dyn_dens.pdf &
  • Input file format:
<LHRS run#> <LHRS file path> <RHRS run#> <RHRS file path> <current> <target#>
  • or, draw directly from tree (adjust bin low/upper limit as needed):
> T->Draw("Rrb.Raster2.rawcur.y:Rrb.Raster2.rawcur.x >> h(100, 0, 1.e5, 100, 0, 1.e5)", "", "colz")
> T->Draw("Lrb.Raster2.rawcur.x:Lrb.Raster2.rawcur.y >> h(100, 0, 1.e5, 100, 0, 1.e5)", "", "colz")