BTA guidelines

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Beam time accounting guidelines (based on Mark D's proposal in Run planning notes, Feb 2 )

Accelerator beam time

  • ABU: acceptable beam used (eg harp scans, calibrations, trigger settings, running)
  • BANU: beam acceptable but not used (eg radiator change or our problems)
  • BNA: beam not acceptable (eg tuning, drifting, not focused)

Experiment beam time

  • ER: experiment ready (when the experiment is ready to accept beam)
  • PCC: planned configuration change (when beam is masked while radiators are moved, etc)
  • UED: unplanned experiment down (unpleasant surprises, hardware failure, extended daq issues)

When the BTA information is loaded from epics it contains automatic calculations of accelerator beam time from beamline monitors and 100% UED experiment down. We have to change this before saving the timesheet.


  • The shift leader should ensure that the accelerator and experiment sides of the timesheet are consistent. The accelerator side is initially filled using the time when beam current was measured in Hall D, assuming that the beam was used only when the DAQ was running. It usually needs to be corrected.
  • First we estimate time spent in UED (hopefully 0) and PCC (configuration changes). Then ER is 60 minutes - (UED+PCC).
  • The BNA value loaded from EPICS is usually reliable, so we can use this to calculate ABU = ER - BNA. The initial BNA value could be too small if Hall D receives only bleedthrough. You might need to estimate BNA from myaplot.
  • If the beam is unavailable then that is counted as BNA, regardless of whatever we are doing (eg PCC).
  • BANU should equal the total time when no beam was requested, BANU = 60 minutes - (ABU + BNA).
  • During physics running, ABU + BANU should be the duration of good quality beam delivery.
  • During initial setup following beam restoration, the beam quality is not so critical, so beam-time spent checking radiation levels and harp scans etc should be counted as ABU.
  • Total time should be estimated without spending excessive time on it. Estimating this from myaplot/myaviewer when the beam is unstable is difficult.
  • If any PCC or UED time is recorded, please write an explanation for this in the Comments field.

The shift leader should also make a log entry at the end of each shift showing the stripcharts for beam current and position following our whiteboard instructions.

* Official machine time accounting user guide

Practical hints

  • The 'load from epics' button is a good starting point but its numbers are often incorrect.
  • Info for MCC: The MCC crew chief shifts end at 3pm, 11pm and 7am. Send 'Info for MCC' as or soon after their shift ends. The upload will include one hour from the previous time sheet.
  • Log BTA: In order to send the BTA to the logbook, go to tab 'Signatures' and and sign it.