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I have added a new system test to provide feedback on overlay simulations.

This page summarizes details of the test and initial release comparisons.
Please comment below to recommend changes and additions. See the suggested new histogram list.

Overlay System Test Configuration

As a starting point, the overlay test (AllGammaOverlay) is run exactly like the system test AllGamma sample with the following exceptions:

  • default overlay job options are included, 
    #include "$OVERLAYROOT/src/MergeAlgs/Overlay.txt";
  • overlay XML input location is specified, 
    OverlayInputSvc.InputXmlFilePath = "path_to_Leon's_latest_overlay_files";
  • RootIo option to avoid memory leak, 
    RootIoSvc.RebuildIndex = false;
  • orbit inclination set, but not relevant for systests (thrown in detector coords) 
    FluxSvc.OrbitInclination = 25.8;

The overlay input files are selected by setting an environment variable.
The overlay event format changes a bit with the releases requiring updates to the file location. Here is what I am using, but I think there may be additional access options.

GR v17r7: Overlay_path=/nfs/farm/g/glast/u31/lsrea/McIlwainL/5-Feb-2009/
GR v17r10: Overlay_path=/nfs/farm/g/glast/u31/lsrea/McIlwainL/18-Mar-2009/

See the note below about the general system test job options.

It produces the same output histograms as AllGamma for now. Probably some things should be added. My short list is below.

Overlay Comparisons

First, is to do a baseline comparison of the overlay and non-overlay versions. I rigged a direct comparison through the systest interface for GR v17r7.
The GR v17r7 run shows the AllGammaOverlay test with the overlays disabled (exactly the same as normal AllGamma). The run GR v17r7OVRLY has overlays turned on. This allows an easy comparison of AllGamma against AllGammaOverlay.
See the failed plots.

One thing I am trying to confirm is that the overlay test is working properly. For example, is it okay to run these with ideal calibrations? Any other configuration issues?

In general, there are more digis and less 0's for all the subsystems. Energies are shifted a bit higher. More triggers and more vetoes. These are not surprises.

There are very noticeable outliers in the TkrDigiLayer and TkrDigiTower plots. I'm not sure what should be special in the overlays for Layers 7 and 17 or Towers 0 and 8? Maybe this is a calibration mismatch? The overlays are derived from data, but the system tests use ideal calibrations.

overlay

no overlay

I also ran tests for GRv17r10 and GRv17r13.
The overall level of digis is reduced. The layer and tower outliers are still there.

A secondary item is if the overlay test is sufficient at the system test level. Do we want additional tests for specific energies or magnetic latitudes?

Miscellanea

System Test Job Options

The system tests (circa GR v17rX) are run using the standard Gleam job options, $GLEAMROOT/src/basicOptions.txt, with only one notable addition:

  • TriggerAlg.applyPrescales = false

The system tests do not pick up calibrations from the database and default to ideal calibrations, i.e. calibration flavor = "ideal".

Another item of note: The default Geant 4 physics model in the basic options is "GLAST". The preferred model is now QGSP_BERT, which includes the updated LPM effect.

Suggested New Histograms for Overlay Test

I picked out some items based on new merit ghost/overlay variables. Please add other parameters of interest (or even better, code).

  • Ghosts in the Tracker
    • TkrNumGhosts
    • TkrNumToT255s
    • TkrNumWideClusters
    • TkrNumWiderClusters
    • TkrNumGhostsOnTracks
    • TkrNumToT255sOnTracks
    • anything else?
  • Overlay event info
    • Overlay event trigger bits
    • Overlay PtMcIlwainL (or PtLambda?)
    • anything else?
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