GlueX Offline Meeting, August 20, 2014

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GlueX Offline Software Meeting
Wednesday, August 20, 2014
1:30 pm EDT
JLab: CEBAF Center F326/327


  1. Announcements
    1. JANA 0.7.2 (David)
  2. Review of minutes from August 6 (all)
  3. Tagger Simulation Update (Richard)
  4. Re-Creating Tracks (all)
  5. Commissioning Geometry Simulation (Sean, Simon)
  6. Analysis of six final states using data challenge 2 MC (Ryan)
  7. BCAL Time Reconstruction Update
  8. Data Challenge 3 (Mark)
  9. Action Items

Communication Information

Remote Connection


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2014-3Q on the JLab CUE. This directory is accessible from the web at .



  • CMU: Will Levine, Paul Mattione, Curtis Meyer
  • FSU: Aristeidis Tsaris
  • IU: Ryan Mitchell, Matt Shepherd
  • JLab: Alex Barnes, Mark Ito (chair), David Lawrence, Nathan Sparks, Mike Staib, Beni Zihlmann
  • MIT: Justin Stevens
  • NU: Sean Dobbs
  • UConn: Richard Jones


  • David has released JANA 0.7.2. Among other features it includes verification of MD5 checksums for resource files.

Review of Minutes from August 6

We looked at the minutes.

Mark "fixed" the broken trunk problem, induced by a change in the table definitions for tagger counters in the CCDB, by simply removing the "exit" in the code when an error is detected in hitTag.c. David reported that Simon Taylor reported that this induced an effective memory leak in the code where the unsuccessful attempt to fetch the constants was repeated for each event, using a small amount of memory each time. Richard thought that rather than trying to fix this, we should wait for the new version of hitTag that actually requires the aforementioned CCDB table change. This will come when the development branch (discussed below) is checked onto the trunk.

Tagger Simulation Update

Richard and Paul have been working on a branch of sim-recon, namely sim-recon-rj-pm, to add realism to the global timing scheme of the simulation.

HDDM Calls: Conversion to C++ API

All invocations of the HDDM API have been upgraded to use the C++ version rather than the old C version. This change comes in many places in the sim-recon tree. The exception is the GEANT-3-based code, in particular the current HDGeant; that conversion will come with the conversion to Geant4.

HDDM Integrity Checks

The HDDM library now supports "integrity checks" where a cyclic redundancy check (CRC) code is computed event-by-event and can be written with the event. Downstream programs can check that incoming data has not been corrupted.

HDDM_s Changes

The template for simulation output has been changed to rationalize the arrangement of data in two areas: (1) the mix of truth and hit information and (2) the detector component hierarchy. A generic example of the latter is using enclosing elements to indicate "layer" rather than encoding "layer" as an attribute of each hit. Note that changes of this nature are indicated in the HDDM_s version in the template contained in every data file.

Merging Strategy

As he has been making these changes, Richard has been periodically merging changes made to the trunk onto his branch. In this way integration testing can proceed on the branch before merge of the branch back onto the trunk.

Tagger Analysis

CCDB tagger tables have been rationalized and new C++ classes introduced in sim-recon to accommodate the new scheme. The start counter was used as a model for the low-level hit classes in the DAQ plug-in. There were some modifications needed to HDGeant (GEANT3) code to write the new classes.

Analysis Library Changes

Paul will need to change the analysis library to deal with the ambiguity of the "correct" tagger hit. For now he will use the factory tag for the tagger to get the true tagger hit. That makes things more or less as things were before. Once the merge onto the trunk is done, he will implement the necessary changes.

Paul and Will have found a problem on the branch where TDC hits from the upstream BCAL are missing. This will have to be fixed by Richard before the merge-back is done.


Beni asked if the new library will support named pipes connecting HDDM producing and consuming programs, e. g. HDGeant to mcsmear. Richard thought that this should have been working all along, but Beni has had trouble getting it to go. We decided to take further discussion offline.


Gxtwist is a stand-alone simulation of the tagger hall. Richard has updated the geometry based on the latest drawings. This has been checked in on the trunk. He has also added reality to the radiator with separate positions for the diamond and the amorphous radiators.

Re-Creating Tracks

There was a discussion on the email list about re-creating tracks with mass hypotheses that are not present in the set coming from track reconstruction. This can be very time-consuming. In these cases usually the fit failed when using the mass assumption in question. Simon is working on solving this problem in tracking so a full set of mass hypotheses are available in the REST file. See the email discussion for details.

Commissioning Geometry Simulation

An effort has started by Sean and Simon to simulate the detector with the commissioning geometry. A branch of HDDS has been made for this work and Simon has started putting in the commissioning target.

Analysis of Six Final States Using Data Challenge 2 MC

Ryan has looked at the following reactions generated in Data Challenge 2:

  1. \gamma p\rightarrow \pi ^{+}\pi ^{-}p
  2. \gamma p\rightarrow \pi ^{+}\pi ^{-}\pi ^{0}p
  3. \gamma p\rightarrow K^{+}K^{-}p
  4. \gamma p\rightarrow \pi ^{+}\pi ^{-}\pi ^{+}\pi ^{-}p
  5. \gamma p\rightarrow \pi ^{+}\pi ^{-}\pi ^{+}\pi ^{-}\pi ^{0}p
  6. \gamma p\rightarrow \pi ^{+}\pi ^{-}\pi ^{+}\pi ^{-}\pi ^{+}\pi ^{-}p

The data set is comprised of 10 M events at 1×107 photon rate, about 1% of the events generated for DC2.

He is using analysis code he developed for use at CLEO and BES. (As a check, Matt has been using Paul's analysis library in a parallel analysis to compare and contrast results. It was in this context that he discovered the track re-creation time sink mentioned above.)

Please see his slides for the plots.

The mass distributions for the multi-pion systems in many reactions peaks much higher than people expected.

Data Challenge 3

Mark has succeeded in creating EVIO format simulation data. Sean told us that reconstruction of this data should not be a problem.

Action Items

  • Fix BCAL bug on tagger reconstruction branch and merge onto trunk. (Richard and Paul)
  • Ask Simon about track re-creation. (Mark)
  • Develop the simulation for the commissioning geometry. (Sean, Simon)
  • Will will send problematic BCAL timing events to Richard. (Will)