Offline Software Glossary

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It is important to have a precise and consistent nomenclature for offline software objects. Generic terms like "event" or "hit" can be very vague and should be avoided. This glossary holds the shared understanding of terms.


Vague Terms

These terms are vague and should not be used when precision is needed.


A true or simulated interaction that leads to measured activity in a detector. This term is probably the most easy to misuse, avoid using it to describe other things.


Simulated or reconstructed primary interaction.

Precise Terms

These terms have precise meanings, in general their authoritative definition can be found in the Logical Data Model documentation

Crate Trigger

All raw data from one crate, corresponding to one detector module. It has an associated time with which it is ordered with other crate triggers by the online. This time may not be as accurate times of the individual instruments contained in the crate trigger's data.

David: The term Trigger is overloaded, hence confusing. I advocate using Nathaniel's idea of calling the raw data from one crate a Fragment and, obviously, a CalibratedTrigger becomes a CalibratedFragment.

Calibrated Trigger

One trigger that has been calibrated for position, time, energy, etc.

Nathaniel says:

"I think this should be changed. "Calibrated Trigger" should just mean: One trigger where low-level calibrations (PMT channel and RPC channel) have been applied.

Then, if position and time finding have been done, call that a "Reconstructed Trigger" Do not specify where "energy" has been calibrated: we will probably have several levels of energy calibration; high-level correction factors might be applied downstream. One can say that at this point there is some sort of corrected, summed pulse-height."

David says:

Good point, Nathaniel. CalibratedTrigger means that all the instruments in the Trigger have had calibration applied to obtain the PE, time and position for each PMT. RPCs merely have position and time. The original specification was too vague.


Tentative physics classification of all or part of a calibrated trigger.

Nathaniel: "Is this just a classification? Nothing else? So, it's just a calibrated trigger with a single datum attached?"

David: No. It is similar to what you have called a Reconstructed Trigger. That is, an algorithm has been applied to determine the best estimate of the parameters of the particle that made the 'footprint'. The parameters can include time, energy, vertex position, direction depending on the type of the Trigger. Oh yeah, it also includes a tentative classification that might just be a (dramatic pause) single additional datum.


Zero or more footprints or zero or more candidates.

comment: Can we get an example of this? Does it hold any data other than just a list of footprints? --Nathaniel

David: No, Nathaniel, you cannot get an example of this. But I'll give one for everyone else, so stop reading here. A muon candidate could combine the Footprint info to make a better estimate of the muon direction. An IBD candidate could be a nGd Footprint preceded by an e+ Footprint.


One or more triggers in time coincidence (~100ns) with out regards to any classification as to the event.


Vauge terms


Try to never use this word as it can take on so very many meanings.

Precise Terms

CMT Package

A CMT Package is a directory under CMT control. In particular it has the file:


It may contain source code, CMT build files, environment setup information or a mix of all the above.