Offline QA Histogram Trigger Types

Offline QA Histogram Trigger Types

  • By default, the Offline QA histogramming code (under StRoot/St_QA_Maker) creates multiple sets of QA histograms (those booked in StQABookHist) for different trigger types.
    • This can be overridden by including the option QAalltrigs in the reconstruction BFC chain. This forces only a single set of histograms to be booked, and all events, regardless of offline trigger ID, are used to fill the histograms.
    • Standard procedure is to run FastOffline with the QAalltrigs option until we have reached physics production mode at the experiment.
  • Each histogram set is booked only upon the first instance of an event which matches the trigger type criteria. This means that if no events matching a specific trigger type are encountered, the histograms for that type will not even be booked.
  • Each event has the potential to match multiple trigger types, and all matching trigger type histogram sets will be filled for each event. This implies that summing histograms from all trigger types can lead to multiple-counting of events.
  • The Offline Trigger IDs stored in each event, StEvent->triggerIDCollection()->nominal()->triggerIds(), are used to determine trigger types.
  • Offline Trigger IDs below 10000 are ignored (assumed to be test triggers), unless the QAalltrigs override is on.
  • Histogram references (for each histogram within a set) to be used by Offline QA may be defined generally for all trigger types, or overridden by a separate reference histogram for specific trigger types.

Any criteria can be used to define a trigger type using the Offline TriggerIDs. We have traditionally used the "hundreds digit" of the Offline Trigger ID is a sufficient tag (i.e. for an Offline Trigger ID of '210987', the hundreds digit is '9'). As of March 16, 2012 (Run 12, start of pp500 operations), the trigger types associated to Offline Trigger IDs are as follows:

Trigger Type Shorthand Description Offline Trigger ID
(hundreds digit)
MinBias-like MB basic collision triggers 0
Central-like CL multiplicity bias 1
High Tower HT single tower energy 2,3
Jet Patch JP tower cluster energy 4,5
Other Physics* XX various 6-9


* Other Physics histograms usually suffer two-fold for QA purposes: (1) they may be a mixture of a variety of triggers, whose relative composition may change from run to run, and (2) they often have fewer statistics than the other triggers.



Some history: chasing a moving target in the st_physics* file steams

Form many years, nothing other than the provided links was posted regarding what Offline Trigger IDs should be used to categorize events for Offline QA and we were left to react. Hopefully, this is now past us.

  • We first started separating histograms by multiplicity class during Run 1.
  • We began using trigger IDs to separate event classes in February, 2003.
  • A request was made to standardize the Offline Trigger IDs in January, 2004, and a convention of 'x5Nxx' was declared, using the hundreds digit N to differentiate physics triggers, with '0' for MinBias, '1' for Central, '2' for EMC (High Tower), '3' for Other Physics, and '4' for L2/L3.
  • In Run 5, physics triggers appeared without restricting the thousands digit to 5.
  • In Run 8, High Tower triggers began to use '5' for the hundreds digit, so we narrowed "Other Physics" to 6-9.
  • In Run 9, there was interest in having histograms for Jet Patch using hundreds digit '4' (i.e. EMC triggers were dividied into two separate groups for High Tower and Jet Patch).
  • In Run 11, MinBias triggers began to use the '1' hundreds digit, so the Cental trigger type was dropped. There were TOF1 and TOF0*VPDMB triggers which used '3' so they were ignored by Offline QA (other TOF triggers used the '0' and '1' digit and were clasified as MinBias). Jet Patch triggers used '6', so they were classified as Other Physics. There were also EMC High Tower triggers (EHT0?, using the EEMC?), which used '8' and were classified as Other Physics. The atomcules triggers used '5', so they were classified as High Tower.
  • In Run 12 pp200 operations, (still no guidance), there are likely the same mis-labelings as in Run 11: an unclassified trigger (BBCMB*TOF0) using the '3' digit (10% of the data?), Jet Patch using the '6' digit, and High Tower (EHT0 : EEMC?) using the '8' digit.
  • In Run 12 pp500, we have agreed on a convention (the one shown above).