Taking MAIN detector Counting Run

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  • Move to Ca-48 target (if you are not already there)
  • Call MCC and ask for 0.3uA cw beam, ask them to set IPM1C12 to normal mode
  • Monitor HALLA:dpp and BPM target locks stripchart, wait until the BPM locks and dpp get stablize
    • HALLA:dpp should be stable ~-1e-4
  • Make sure the raster size is 2x2 mm^2 and beam is collimator centered
  • Turn ON Scintillators (Follow the instructions in HVgui)
  • Monitor the scaler GUI, the T1 rate on both arms should be ~200k
    • Be careful, consider the safety of VDCs --> Look into white board for VDC safe zone
  • Turn ON VDCs (NOTE: Again, make sure the scintillator rate is below 500k before turning VDC ON)
  • Set the HV for DN-Quartz (MAIN) detectors in both arms to -1900V (as explained in HVgui). Note: If this is a Q-square run and all the detectors (MAIN and AT) are in counting mode, ATin (RHRS) should be set to -1800 V and all other detectors should be set to -1900 V.
    • L1.1 channel in S1 (Slot1) in each arm HV GUI (See Image 1)
    • Enable the HV channels
    • Important Note: Once you are done with counting Run Turn this channel OFF and set the value to 0.0
Image 1
  • Make sure that the IPM1C12.XPOS and HALLA:dpp stripcharts are working
  • Click on the HALLA:dpp stripchart to mark the time and value of dpp (Again, it should be stable ~-1e-4)
  • Take counting runs on both arms (LHRS and RHRS) at least 200k events
  • To analyze the runs:
    • ssh -Y a-onl@aonl1
    • goprex
    • analyzer -l
    • .x setup3.C(runNumber,200000)
  • The rootfiles are stored in /chafs1/work1/prex_counting/
  • To produce plots:
    • In a-onl@aonl1 machine:
    • cd devi/crex/alignment
    • analyzer prex_counting/prexLHRS_runNumber_200000.root for LHRS
    • analyzer prex_counting/prexRHRS_runNumber_200000.root for RHRS
    • .x alignDS.C (Note: if the alignment was performed with upstream detectors, need to use alignUS.C macro)
    • Note: please don't modify the macro, if you want you can copy it to your directory and modify there
    • Look into the elastic peak and read the edge of quartz (the intersection of red and blue histograms in "Projected x on detector plane" plot)
    • Often the Mean and Edge values labeled in the plot do not show accurate
    • Zoom in to see the precise edge
    • If everything is OK, and the HALLA:dpp during the run is ~-1e-4 the elastic peak and edge position should be the following:
      • LHRS --> Elastic Peak: -0.012 m, Edge: ~-0.0305 m giving the difference ~18.5 mm
      • RHRS --> Elastic Peak: -0.0465 m, Edge: ~-0.064 m giving the difference ~17.5 mm (Note:: The US sees ~1mm more than DS from previous analysis)
      • Note:: If the fit is not working properly, carefully look into the peak
      • Compare with the alignment from 01/25/2020 (good alignment) HALOG
      • Also look into the latest alignment from 03/23/2020 (when LHRS has quite large acceptance) HALOG
    • If these numbers are different by more than 1 mm, monitor how HALLA:dpp is doing, also monitor the Dipole set values and readback values
    • If both arms are showing the shift, if any, in the same direction, it is more likely the energy is changing
    • If only one arm is showing the shift, if any, it is more likely due to the magnet settings in the arm
    • If you have any doubt, or can't resolve the issue, call expert
    • For every run, halog the plots. Also halog the HALLA:dpp stripchart (showing the marked value)
  • When you are done with taking counting data turn OFF the DN-Quartz (MAIN) detectors, VDCs and Scintillators HVs. Note: If this is a Q-square run and all the detectors are in counting mode turn OFF all the MAIN and AT detectors, set the HV of UP-Quartz (US MAIN) and AT detectors for production settings.
  • NOTE: never turn ON DN-Quartz and VDCs HVs during high current production running keeping them at higher HV (they will die)
  • For safety, set their HV to 0.0V at the end
  • NOTE: Remember to turn ON UP-Quartz and AT detectors before going to production