News and Status

• 09-Feb-2003 LArG4 now functions within AtlasG4Sim; see below.
• 23-Jul-2003 The LAr Geant4 geometry is being converted into GeoModel; see the description of LArGeoModel below.
• 30-May-2002 A major new release of the LAr Geant4 simulation; see below.
• 04-Apr-2001 Improved ROOT I/O timing study, including the effects of TClonesArrays and ROOT compression methods.
• 12-Feb-2001 Results of a ROOT I/O timing study with LAr-style events.
• 21-Sep-1999 Report on a GEANT4 implementation test of barrel EM calorimeter.

Applications

LArGeoModel is a description of the LAr calorimeter geometry based on the GeoModel package. You can access the LArGeoModel code in the ATLAS CVS Repository via this link. There is a document available (179KB PDF) that describes the GeoModel conversion procedure.

LArG4 is a practical ATLAS-based application of the examples below. It implements the LAr calorimeter geometry in Geant4, and generates events with hits.

• LArG4 now functions within AtlasG4Sim, the Geant4 simulation of the entire ATLAS detector. The package that "links" LArG4 with AtlasG4Sim is LArG4Sim; consult the documentation for the LAr-specific options of the simulation.

  You can still run LArG4 by itself, using the packages LArG4Algs within Athena, or LArG4App external to Athena; see the LArG4 documentation for details. Note that these "LArG4-only" packages are likely to become deprecated as AtlasG4Sim matures.

• Changes to LArG4 are still being released at regular intervals. However, rather placing new links to tarballs on this page, it's suggested that you get the the code directly from the LArG4 area in the ATLAS CVS Repository.

• Version 00-11-01 (posted 27-Mar-2003).
  • Among the changes in this version:
    • visual and sensitive-detector consultants, to ease the transition into GeoModel;
    • compatibility with Athena release 6.0.0;
    • LArG4Hbook, a package for creating PAW-compatible n-tuples in the stand-alone application;
    • additional documentation.

• Version 00-10-12 (posted 24-Jan-2003).
  • This version includes many improvements and additions to the LArG4 geometry, including:
    • the FCAL geometry;
    • the HEC tie rods;
    • the barrel presampler;
    • improvements in EMEC structure.
  • There have been changes in how the stand-alone version is set up. Please re-read LArG4/doc/README.stand-alone to keep up-to-date.

• Version 00-10-07 (posted 15-Nov-2002).
  • In addition to some bug fixes, this release includes an embedded MySQL server prepared by Alexandre Vaniachine. This is useful if you want to run the stand-alone version on a machine without an active network connection.

• Version 00-10-03 (posted 18-Oct-2002).
  • This release has been organized to be completely compatible with working in Athena. There are also a few bug fixes, so even if you're not using Athena yet, please download this version.

• Version 00-08-02 (posted 12-Sep-2002).
  • Again, this is a major new release.
  • The HEC is now part of the simulation (thanks to Gaiane Karapetian).
  • Andrei Soukharev has made many improvements to the EMEC geometry.
  • Modifications were made to the package structure to improve Athena compatiblity. In particular, the package can now be fully compiled and executed within the Athena TestRelease environment (see LArG4/doc/README.Athena). Full Athena compatility should come by Athena release 4.4.0.
  • Other bug fixes and minor improvements; see the ChangeLog.

• Version 00-08-01 (posted 19-Jul-2002).
  • This is another major new release. The hit processing has been changed to make use of "cell identifiers". This allows each sub-detector to have its own hit structure. This required enough of a revision to the headers as to require an update to the version number (from 07 to 08).
  • The package is renamed from LArG4Sim to LArG4 as the package design continues to approach the Athena standard.
  • Some minor bugs have been fixed.

• Version 00-07-08 (posted 30-May-2002).
  • This is a major new release. The most important change is that this version has some measure of compatiblity with Athena, the ATLAS software framework. Part of that change is a renaming of the package from LArHits to LArG4Sim to fit the Athena naming conventions and functions.
  • There are many other changes, both major and minor. Please look at the LArG4Sim/README and the Applications Guide in LArG4Sim/doc for more information.

• Version 0.6.2 (posted 19-Nov-2001). See Version 0.5.0 for the documentation.
  • Additional bug fixes and corrections due to continuing work on the endcap geometry.

• Version 0.6.1 (posted 01-Nov-2001). See Version 0.5.0 for the documentation.
  • This is an interim release that fixes some serious bugs in the endcap geometry. However, there are still bugs that are being actively worked on, and a new release is anticipated shortly.
  • Other minor bug fixes.

• Version 0.6.0 (posted 18-Oct-2001). See Version 0.5.0 for the documentation.
  • The LAr barrel and endcap cryostats are now included in the simulation.
  • Fixed some serious bugs in the endcap tracking geometry.
  • Other minor bug fixes.

• Version 0.5.0 (posted 09-Jul-2001). Documentation is available in Postscript, PDF, and HTML.
  • Fixed ROOT compatibility problem. LArHits is now compatible with ROOT 3.00/06 and 3.01/05.
  • Minor bug fixes.

• Version 0.4.2 (incremental release, posted 28-Jun-2001).
  • Corrections to LAr endcap geometry and improvements to LArEndcapConstruction.
  • The one FORTRAN routine has been eliminated.
  • There is now only one hit-processing sensitive-detector routine that is shared between different detectors.
  • Minor bug fixes.

• Version 0.4.1 (incremental release, posted 26-Jun-2001).
  • Improvements in code documentation (README and ChangeLog files).
  • The only significant code change from version 0.4 (see below) is compatibility with ROOT 03.01/05. Note that version 0.4.1 is only compatible with ROOT versions equal or later than 03.01; version 0.4 is only compatible with ROOT version 3.00. If you are not using ROOT 03.01 yet, then you should not download LArHits 0.4.1. We are working on this issue, and hope that version 0.5 will be compatible with all recent and current versions of ROOT.

• Version 0.4 (posted 21-May-2001). Documentation is available in Postscript, PDF, and HTML.
  • Includes the LAr Endcap Calorimeters, based on Andrei Soukharev's LArWheelSolid (see below).
  • Improved and generalized logic for accumulating Geant4 hits.
  • Improved LArBarrelSolid geometry and visualization code.
  • Miscellaneous bug fixes.

• Version 0.3 (posted 09-Apr-2001). Documentation is available in Postscript, PDF, and HTML.
  • Includes the z<0 portion of the LAr barrel.
  • Optimized the ROOT persistency scheme for I/O speed by using TClonesArrays as the container classes for primary particles and hits.
  • Modified hit class to use a separate LArCellID class. If this code is ever integrated into Athena, this will be changed to the Identifier class.
  • Miscellaneous bug fixes.

• Version 0.1 (posted 15-Dec-2000).
  • Implements the calorimeter geometry for z > 0 with a "tailored" geometry using a customized class LArBarrelSolid inheriting from G4VSolid.
  • Outputs a LArRootEvent class using the ROOT-based persistency scheme demonstrated in example R05 below. The persistency scheme can be a little confusing; perhaps this diagram can help.
  • Includes a sample ROOT application, analysis.C, that histograms out-of-time hits in 50-GeV electron events.

LArWheelSolid is an implementation of the LAr endcap calorimeter as a Geant4 solid. The source code (tar.gz format) is available, as is the documention in both Postscript and PDF.

Examples

• Here are (somewhat large) .eps files with pictures of a portion of the LAr barrel accordion (7 MB), a 10 GeV electron event (18 MB) in the calorimeter with all particles shown, and a 10 GeV electron event with only charged particles shown (9.2 MB).

• The RecorderBase class is an abstract base class useful in Geant4 for implementing histograms and similar recording objects within a single class.

  • R06: As an alternate approach, we tested the use of ROOT Object I/O directly instead of ROOT Trees. This example (tar.gz format) implements that suggestion. It also shows an example of a ROOT macro that can either be interpreted or compiled.
    • Added 22-Nov-2000; tested with ROOT 2.25/03, Geant 4.2.0ref2, and the gcc 2.95.2 compiler.
    • Revised 05-Dec-2000 for memory leaks when reading output in a ROOT application. Note that timing studies show Tree-based I/O is faster than direct Object I/O, at least for the small event and hit classes used in this example.
    • 24-Jan-2001: A revision to the above comment. It turns out that for up to about 10,000 objects in a file, direct object I/O is faster. At about 50,000 objects or above, Tree-based I/O is faster. A more complete timing study is underway; the results should be released shortly.
    • 04-Apr-2001: The timing studies with example R06 were expanded into the LAr event ROOT timing studies, part 1 and part 2. The source code for that study is available here (in tar.gz format). Bottom line: The most efficient I/O scheme uses TTrees with splitlevel=l and TClonesArrays for all container classes.

  • R05: Here is our initial attempt to provide a ROOT-based persistency mechanism for Geant4 (tar.gz format).
    • Added 30-Oct-2000; tested with ROOT 2.25/03, Geant 4.2.0ref2, and the gcc 2.95.2 compiler.
    • Revised 13-Nov-2000 for TVector3 class.
    • Revised 05-Dec-2000 for memory leaks when reading output in a ROOT application.

  • R04: This revision to example N02 in the standard G4 distribution illustrates how to mix the Geant4 hit mechanism with ROOT (tar.gz format).
    • Added 04-Oct-2000; tested with ROOT 2.25/03, Geant 4.2.0ref2, and the gcc 2.95.2 compiler.

  • R03: This example (tar.gz format) shows how to mix Geant4 and ROOT, at least to the extent of making histograms and ntuples.
    • Revised 22-Dec-1999 for ROOT 2.23/10 and Geant 4.1.0.

  • R02: Here's another example (tar.gz format) of how to use this class to sample and display variables.

  • R01: Here's an example (tar.gz format) of how to use this class and the existing Geant4/CLHEP functionality to make histograms in Geant 4.0.1.
    • Unfortunately, this example will no longer work with recent versions of Geant4. The reason is that the newer versions of CLHEP (1.5 onwards) do not have HBOOK compatibility built-in.

Related Web Sites

• The ATLAS experiment is located in the Large Hadron Collider at CERN.

• The US is participating in the ATLAS project, including the software development.

• One participant in USATLAS is Nevis Laboratories, a facility for experimental physics research operated by the Columbia University Physics Department.

• The ATLAS detector will be simulated using GEANT4. Portions of GEANT4's functionality are implemented using CLHEP. We are also studying how to integrate ROOT with GEANT4.

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