BTA guidelines

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Revision as of 12:47, 9 March 2020 by Elton (Talk | contribs) (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
  • PCC: planned configuration change (when beam is masked while radiators are moved, etc)</li>
  • UED: unplanned experiment down (unpleasant surprises, hardware failure, extended daq issues)</li></ul>


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.


Guidelines

  • The shift leader should ensure that the accelerator timesheet is consistent with ours.
  • 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.
  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.
  • The MCC crew chief shifts end 1h before ours, so they need 'Save info for MCC' to be done as or soon after the 7th hour of our shift ends.