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Lhlay (Lelaps)

Lelaps, Canis Major


Lelaps  is a fast detector simulation program and a number of C++ class libraries, the most important one being CEPack, the main simulation tool kit. Main programs (lelapses) have been written for BaBar and for LCD (LDMar01, SDJan03 and SDMar04 are implemented). CEPack can also be used in conjunction with Geant4 parameterized volumes. In this way it is integrated in BaBar's Geant4-based simulation. The standalone version for LCD reads GODL detector description files in addition to three built-in geometries and StdHep generator files using the (included) lStdHep class library, and it produces SIO or LCIO output files that can be read by JAS and Wired. It swims particles through detectors taking into account magnetic fields, multiple scattering and dE/dx energy loss. It produces parameterized showers in EM and hadronic calorimeters, converts gammas, supports decays of certain short-lived particles (V decays), and it does all this very fast.

Matprop is a little program that comes with the Lelaps distribution. It allows one to enter all sorts of materials or mixtures and view various properties. An online version of matprop is available here.

GODL is a detector description language. Two GODL files are included with the Lelaps distribution as examples: SDJan03.godl and SDMar04.godl. GODL files can also be made from "compact descriptions" using the GeomConverter utility.

HepRep support is provided using an included utility called godlheprep, which makes HepReps from a GODL file. These HepReps can be read using the latest version of Wired 4.


Latest Version V03-27-28

To get a particular version type:

   cvs -d checkout -r <version> lelaps

To compile on Solaris (5.9, Sun CC 5.4), Linux (Redhat RHEL 3, gcc 3.2.3) or Cygwin (with gcc 3.3.3), cd to the lelaps directory and type "make". To run the compiled program, cd to the lelaps directory (the one within the first lelaps directory) and type lelaps -h for a list of command line options. Typical usage:

   lelaps -L detector.godl -o output.slcio -E input.stdhep


The following papers and presentations on Lelaps should serve as a good start while better documentation is still being worked on.

Lelaps, LCD Simulation Workshop, 22 May 2003 (PowerPoint)
Shower Parameterization in Lelaps, August 2003 (Daniel Birt and Amy Nicholson, PowerPoint)
Parameterized Shower Simulation in Lelaps: a comparison with Geant4, August 2003 (Birt et al., Postscript, PDF)
Lelaps, ALCPG Workshop, 9 January 2004 (PowerPoint)
Lelaps, LCD Seminar, 15 January 2004 (PowerPoint)
Lelaps, LCWS Paris, 18 April 2004, presented by Michael Peskin (PowerPoint, PDF)
Lelaps, ALCPG Workshop, 28 July 2004, Victoria, BC, Canada (PowerPoint)
Fast Detector Simulation Using Lelaps, SLAC-PUB-10663, August 2004 (PostScript, PDF).
Generalized Object Description Language (GODL), 11 January 2005 (PowerPoint).
Lelaps and GODL, Linear Collider Simulation Workshop (LCSim '05), SLAC, 17 March 2005 (PowerPoint).
Lelaps and GODL, Linear Collider Workshop (LCWS '05), Stanford, 19 March 2005 (PowerPoint).
Fast Simulation Using Lelaps, Detector Descriptions in GODL, SLAC-PUB-11328, June 2005 (pdf).

About Lelaps

Lelaps headquarters is at SLAC. For questions and comments, send email to the author. Lelaps is part of the Freehep repository but it is not in the public domain.

About  the name "Lelaps":

Lelaps (storm wind) was a dog with such speed that, once set upon a chase, he could not fail to catch his prey. Having forged him from bronze, Hephaestus gave him to Zeus, who in turn gave him to Athena, the goddess of the hunt. Athena gave Lelaps as a wedding present to Procris, daughter of Thespius, and the new bride of famous hunter Cephalus. A time came when a fox created havoc for the shepherds in Thebes. The fox had the divine property that its speed was so great that it could not be caught. Procris sent Lelaps to catch the fox. But because both were divine creatures, a stalemate ensued, upon which Zeus turned both into stone. Feeling remorse, Zeus elevated Lelaps to the skies, where he now shines as the constellation Canis Major, with Sirius as the main star.

Willy Langeveld - Last update: September 1, 2004