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

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

Open Panguin

  • Check if an instance of panguin is already running on the machine.
  • If not, open a terminal and follow the steps below:
    • Type "ssh apar@aonl1 -Y".
    • Enter the password when prompted.
    • If you do not know the password, ask the analysis shifter.
    • Type "panguin". A GUI window will pop up.
    • Click on the radio buttons to choose which plots to look at.
    • Type “offline_panguin RUNNUMBER” to look at older data for comparison.

What to look for

For more detailed information, see full article: Online Plots. For a quick overview, read on.

The main challenge in parity experiments such as PREX is to make sure that other parameters of the beam such as energy and position do not fluctuate during spin flipping. These fluctuations can mimic the effect of weak interaction. The panguin plots display the readback of monitors used to keep track of beam parameters and are important tools to ensure good data quality. A brief description of pages displayed by panguin can be found below:

Crucial Systems

  • The top left window shows the reading from one of the beam current monitors (BCMs). The vertical axis shows beam current in units of uA and the horizontal axis shows CodaEventNumber which is a measure of time. During production mode running on isotropic Lead-208 target, we will mostly be running at 70 uA. But consult the shift run plan to make sure you know what current we are operating at for your particular shift. Log any sudden changes or large fluctuations for runs in the run summary when the beam is not tripping.
  • The top right window shows the output from one of the four wires that are used to calculate beam position by the beam position monitor (BPM) sensitive to energy fluctuations. Check for signs of saturation and large fluctuations.
  • The bottom left window shows the average asymmetry measured by our detectors in the left and right HRS.
  • The bottom right window shows vital statistics from the three plots in this page. If a large number of events are failing the event cuts or the BPM is saturated most of the time, alert the analysis shifter who will consult the WAC.

Event Cuts

  • The upper box displays event statistics for all events upto the present event being analyzed. The lower box displays the event statistics for the most recent 20000 events. If these stats differ too much during stable beam periods, alert the analysis shifter.

EventCut: Target BPMs

  • BPM 4a and BPM 4e are the BPMs most sensitive to position fluctuations. The top 4 windows display position coordinates in mm vs time for the two BPMs. Check for signs of large fluctuations and saturation in these plots. The bottom 4 windows display the beam position differences between different helicity (spin) states recorded by each BPM. If the means or widths of these distributions change over time, alert the analysis shifter.