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
  • 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.


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.