Running SLIC Events in Pandora PFA New

Overview

This tutorial will show you how to process SLIC output files with the Pandora Particle Flow Algorithm to produce Particle Flow Objects (PFOs) for analysis. PFOs are represented by the ReconstructedParticle class in the LCIO event data format.

These instructions cover building and installing a slic-specific frontend called slicPandora and all its dependencies. Then the steps will be shown for processing the output using LCSim in order to prepare it for Pandora. Finally, there are instructions for running these events in slicPandora. There is also a brief section on generating a Pandora detector XML file from a compact detector description, the XML format used by lcsim to represent detector and geometry information.

Building SlicPandora

Preliminary Setup

A Linux or Unix platform is assumed and the bash shell is used for all command-line instructions. The actual setup procedures have been tested on Redhat Enterprise Linux 5.5 (Tikanga).

You will need the standard GNU tools installed, e.g. Make, gcc/g++, etc.

The cvs and svn command-line tools are also required for obtaining project source codes.

The cmake tool must be installed, as it is used to build most of the dependencies.

Dependencies

The slicPandora package currently has the following dependencies.

There are build instructions below that show all the steps necessary to build these packages.

Build Instructions

These commands can be executed to produce a working slicPandora.

Start by making a directory where Pandora and its dependencies will be installed.

This is just an example. Any directory with enough space will do.

mkdir /work/pandora_build
cd /work/pandora_build

The following commands should then be executed in order from this working directory to make the slicPandora binary.

ilcutil

svn co http://svnsrv.desy.de/public/ilctools/ilcutil/trunk ilcutil
cd ilcutil
cmake .
make install
export ILCUTIL_DIR=`pwd`
cd ..

Pandora

svn co http://svnsrv.desy.de/public/PandoraPFANew/PandoraPFANew/trunk PandoraPFANew
cd PandoraPFANew
mkdir build
cd build
cmake ..
make install
cd ..
export PandoraPFANew_DIR=`pwd`/PandoraPFANew

LCIO

cvs -d :pserver:anonymous@cvs.freehep.org:/cvs/lcd co -r v01-51 lcio
cd lcio
mkdir build
cd build
cmake -DINSTALL_DOC=OFF -DBUILD_32BIT_COMPATIBLE=OFF ..
make install
cd ..
export LCIO_DIR=`pwd`
cd ..

slicPandora

cvs -d :pserver:anonymous@cvs.freehep.org:/cvs/lcd co slicPandora
cd slicPandora
mkdir build
cd build
cmake -DILCUTIL_DIR=$ILCUTIL_DIR -DLCIO_DIR=$LCIO_DIR -DPandoraPFANew_DIR=$PandoraPFANew_DIR ..
make install

Pandora Settings (optional)

You should also check out the project that contains sample config files for Pandora.

svn co http://svnsrv.desy.de/public/PandoraPFANew/Settings/trunk PandoraSettings

LCDetectors (optional)

There are sample slicPandora geometry xml files here. This is a rather big cvs module so might take some time to checkout.

cvs -d :pserver:anonymous@cvs.freehep.org:/cvs/lcd co LCDetectors

PandoraFrontend

The PandoraFrontend binary provides a simple frontend to slicPandora.

The syntax of this command is the following.

./bin/PandoraFrontend geometry.xml pandoraSettings.xml inputEvents.slcio reconOutput.slcio [nevents] [nskip]

This table explains the function of each of these arguments.

The geometry file is in XML format. It can be created from a compact detector description using GeomConverter.

Using GeomConverter to Output the Pandora Geometry Format

The GeomConverter package can convert from compact detector descriptions to various output formats, including one for input to slicPandora.

For example, to generate the Pandora settings for the sidloi3 detector.

cvs -d :pserver:anonymous@co LCDetectors
cd LCDetectors/detectors/sidloi3
java -jar ~/.m2/repository/org/lcsim/GeomConverter/1.13-SNAPSHOT/GeomConverter-1.13-SNAPSHOT-bin.jar -o pandora compact.xml sidloi3_pandora.xml

This will create the file sidloi3_pandora.xml that can be used as input to slicPandora.

Running Events in SlicPandora

Steps

The essential steps to generating events with SlicPandora are as follows.

1) Use SLIC to generate an LCIO file.
2) Add tracks to the event by running a tracking package such as LCSim's SeedTracker.
3) Add the TrackState collections so slicPandora knows the Track momenta. (can be combined with #2 into one LCSim job)
4) Run SlicPandora with the LCSim output, a Pandora XML geometry generated by GeomConverter, and a Pandora settings XML file.

These steps are covered in more detail below.

Generating Tracks Using LCSim

Before the simulated LCIO events can be run through Pandora, the LCSim tracking needs to run in order to add a collection of tracks.

If you don't know how LCSim batch mode works, then review the LCSim XML instructions.

Tracking Steering File

Below is an example XML steering file for LCSim to generate the Tracks and TrackStates for the sidloi3 detector.

<lcsim xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
        xs:noNamespaceSchemaLocation="http://www.lcsim.org/schemas/lcsim/1.0/lcsim.xsd">
    <inputFiles>
        <file>./pi_Theta90_10GeV-0-1000_SLIC-v2r8p3_geant4-v9r3p1_QGSP_BERT_sidloi3.slcio</file>
    </inputFiles>
    <control>
        <numberOfEvents>1000</numberOfEvents>
        <verbose>true</verbose>
        <printSystemProperties>false</printSystemProperties>
    </control>
    <execute>
        <driver name="EventMarkerDriver"/>
        <driver name="CalInfoDriver"/>
        <driver name="MainTrackingDriver"/>
        <driver name="TrackStateDriver"/>
        <driver name="Writer"/>
    </execute>
    <drivers>
        <driver name="CalInfoDriver"
                type="org.lcsim.recon.util.CalInfoDriver"/>
        <driver name="MainTrackingDriver"
                type="org.lcsim.recon.tracking.seedtracker.trackingdrivers.sidloi2.MainTrackingDriver"/>
        <driver name="EventMarkerDriver"
                type="org.lcsim.job.EventMarkerDriver">
            <eventInterval>10</eventInterval>
        </driver>
        <driver name="TrackStateDriver"
                type="org.lcsim.recon.tracking.seedtracker.SeedTrackerTrackStateDriver"/>
        <driver name="Writer"
                type="org.lcsim.util.loop.LCIODriver">
            <outputFilePath>./pi_Theta90_10GeV-0-1000_SLIC-v2r8p3_geant4-v9r3p1_QGSP_BERT_sidloi3_lcsimTracking.slcio</outputFilePath>
        </driver>
    </drivers>
</lcsim>

The input files section needs to be changed to point to your local simulated SLIC events, and the outputFilePath would also be changed to have a name based on the input file. You can easily make a script to automate this.

More LCSim Tracking Details

The LCSim job must accomplish three tasks before the events can be read into Pandora, in this order.

1. Generation of a Tracks collection using an appropriate Seed Tracker Driver.
2. Adding TrackState collections using the SeedTrackerTrackState Driver.
3. Writing out the necessary LCIO collections to a data file to be read into Pandora.

To generate the Tracks, a top-level Driver should be run that covers subdetector setup, digitization, and track finding and fitting. This top-level Driver will likely be specific to a certain detector design.

For instance, this simple Driver definition is sufficient to generate tracks in the sidloi3 detector.

 <driver name="MainTrackingDriver"
         type="org.lcsim.recon.tracking.seedtracker.trackingdrivers.sidloi3.MainTrackingDriver"/>

Three TrackState collections need to be added to the LCIO output to provide Pandora with track information at the track origins, the ECal, and the end point.

The following Driver in the Seed Tracker package will add these necessary TrackState collections. This Driver also requires that another Driver be run beforehand to cache Calorimeter subdetector data.

<driver name="CalInfoDriver"
        type="org.lcsim.recon.util.CalInfoDriver"/>
<driver name="TrackStateDriver"
        type="org.lcsim.recon.tracking.seedtracker.SeedTrackerTrackStateDriver"/>

Finally, an LCIODriver should be added to the end of the event processing to output the appropriate collections.

<driver name="Writer"
        type="org.lcsim.util.loop.LCIODriver">
            <outputFilePath>OUTPUT_FILE</outputFilePath>
</driver>

The OUTPUT_FILE argument needs to be replaced with the actual name of the LCIO output file to be fed to Pandora.

Once these Drivers are defined in the <driver> section of your LCSim XML file, the execution order should look like the following.

<execute>
    <driver name="CalInfoDriver"/>
    <driver name="MainTrackingDriver"/>
    <driver name="TrackStateDriver"/>
    <driver name="Writer"/>
</execute>

Now that tracks and track states have been added to the events, we are ready to use Pandora itself.