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Detector simulation with FPadSim

In many cases, HepSim detector simulations were done using SiD-derived software.

To create full simulations, you will need to convert ProMC files to LCIO files. This is described in LCIO conversions.

Many samples posted in HepSim are created with the package called “fpadsim” (Future Particle Detector Simulator“). This package is under constant development. The contributed authors of this package since 2015 are:

  • D.Blyth (HEP/ANL)
  • J.MacCormick (SLAC)
  • W.Armstrong (PHYS/HEP)
  • S.Chekanov (HEP/ANL)
  • A.Kotwal (Duke)
  • J.Strube (PNNL)
  • J.Marshall (U.Cambridge)

The package includes packages from ilcsoft, such as SLIC, PandoraPFA, and LCSIM The simulation and reconstruction proceeds as: SLIC→LCSIM→slicPandora/PandoraPFA. This digram shows the entire chain:

The input for SLIC are LCIO files with truth-level information (“MCParticle” table). The files are created from ProMC files using the converter promc2lcio (included inside the ProMC packages, in the directory “examples”). This concept originates from the SiD detector(T.Johnson, N.Graf, J.McCormick, J.Strube), and later was re-purposed to be used for generic feature detectors, including proton pp colliders (S.Chekanov, A.Kotwal). The final step of the reconstruction is PandoraPFA (J.Marshall, M.Thomson).

To create LCIO files with full simulations and reconstruction, you need:

  • ProMC file from HepSim
  • Simulation and Reconstruction package called “fpadsim-[version]”.
  • Tag file which includes detector and the simulation and reconstruction sequence.

The fpadsim package is located here. It is usually designed for the OSG grid. The tag files are also located here. They have the names “rfull[XXX].tgz”. After untaring the file fpadsim.tgz, untar the file “rfull[XXX].tgz”. There is a simple script “Test.sh” that creates a few events and illustrate this concept. Note that the version of fpadsim is defined inside the script A_RUN used to create reconstructed events.

Changes in compact.xml

If you want to make changes in the detector design, edit “compact.xml”, and then run the converters:

JAVA_OPTS="-Xms2048m -Xmx2048m"
GCONVERTER=lcsim/detector-framework/target/lcsim-detector-framework-3.1.6-SNAPSHOT-bin.jar
GEOM="mydetector" # name of your detector
java $JAVA_OPTS -jar $GCONVERTER -o lcdd compact.xml $GEOM.lcdd
slic -g ${GEOM}.lcdd  -G ${GEOM}.gdml
echo "heprep compact.xml.."
java $JAVA_OPTS -jar $GCONVERTER -o heprep compact.xml $GEOM.heprep
echo "pandora compact.xml.."
java $JAVA_OPTS -jar $GCONVERTER -o pandora compact.xml $GEOM.pandora
java $JAVA_OPTS -jar $GCONVERTER -o html compact.xml ${GEOM}.html

where “${GEOM}” is the name of the detector geometry. Next, check that you do not have overlapping volumes. Run ROOT with the commands:

TGeoManager::Import("mydetector.gdml");
gGeoManager->ViewLeaves(true);
gGeoManager->ls("All");
gGeoManager->CheckOverlaps(0.1); //0.1 tolerance or better!
gGeoManager->PrintOverlaps();
gGeoManager->GetTopVolume()->Draw("ogl");

If you see that some volumes overlap, come back to “compact.xml” and make corrections.

Pandora PFA

All information required by Pandora algorithm is stored in the file with the extension ”.pandora“. This file is created using GeoConvertor, which reads CalorimeterCalibration.properties file. In particular, it reads:

  • mipEnergy
  • mipSigma
  • mipCut
  • timeCut

The sampling fractions are taken from the detector directory called “SamplingFractions”. Here files look as this:

BeamCal.properties*
EcalBarrel.properties*
EcalEndcap.properties*
HcalBarrel.properties*
HcalEndcap.properties*
LumiCal.properties*
MuonBarrel.properties*
MuonEndcap.properties*
README*

Look at the file:

lcsim/detector-framework/src/main/java/org/lcsim/geometry/compact/converter/pandora/Main.java

Sergei Chekanov 2017/04/12 21:58