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CMakeLists.txt
CMakeLists.txt
 
 
README.md
README.md
 
 

README.md

ITS3

Upgraded version of the ITS that includes upgraded truly-cylindrical inner barrel. Provided O2 has been compiled with upgrades enabled (ENABLE_UPGRADES=1 aliBuild build O2), it is possible to simulate ITS3 geometry within the o2-sim executable.

Events can be simulated using the o2-sim workflow. To include ITS3 in the simulation, IT3 module must be enabled via the -m IT3 parameter. To include the beam pipe, the module PIPE must be enabled.

The run number is needed to retrieve objects from the CCDB. There are specific ranges of run-numbers, according to the collision system and to the selected geometry if the ITS3 inner barrel:

  • pp collisions:

    • 303901—303999

  • Pb-Pb collisions:

    • 311901—311999

Note: For now the same topology dictionary will be used for both collision-systems Last Update of file here (jira)[https://its.cern.ch/jira/browse/O2-4698]

Simulation

  1. Optional

This just caches the ccdb object to reduce calls in case we are testing.

export IGNORE_VALIDITYCHECK_OF_CCDB_LOCALCACHE=1
export ALICEO2_CCDB_LOCALCACHE=${PWD}/ccdb

Simulate diamond

# append to o2-sim
--configKeyValues="Diamond.width[2]=6.;""

Local Tracking

  1. Simulate

Simulate PIPE and ITS3

o2-sim -g pythia8pp -j10 -m PIPE IT3 --run 303901 -n1000

In the previous command:

  • -j is used to set the number of threads;
  • -n is used to set the number of events to simulate;
  • -g is used to set the event generator, in this case pythia8hi. To simulate pp collisions one can use pythia8pp.
  • --run is needed to set the run number.
  1. Digitization
o2-sim-digitizer-workflow -b --interactionRate 50000 --run --configKeyValues="HBFUtils.runNumber=303901;" --onlyDet IT3
root -x -l ${ALIBUILD_WORK_DIR}/../O2/Detectors/Upgrades/ITS3/macros/test/CheckDigitsITS3.C++
  1. Clusterization with tracking
o2-its3-reco-workflow -b --run --tracking-mode async --configKeyValues "HBFUtils.runNumber=303901;"
root -x -l ${ALIBUILD_WORK_DIR}/../O2/Detectors/Upgrades/ITS3/macros/test/CheckClustersITS3.C++
root -x -l ${ALIBUILD_WORK_DIR}/../O2/Detectors/Upgrades/ITS3/macros/test/CheckTracksITS3.C++

Global Tracking

  1. Simulate

Simulate all detectors but replacing ITS with IT3

o2-sim -g pythia8pp -j10 --detectorList ALICE2.1 --run 303901 -n20 -m IT3

Creating CCDB Objects

!TODO! Create Full geometry + Aligned + GeometryTGeo

# Create Full Geometry
o2-sim -g pythia8pp -j10 --detectorList ALICE2.1 --run 303901 -n0
cp o2sim_geometry.root ${ALICEO2_CCDB_LOCALCACHE}/GLO/Config/Geometry/snapshot.root
o2-create-aligned-geometry-workflow -b --configKeyValues "HBFUtils.startTime=1547978230000" --condition-remap="file://${ALICEO2_CCDB_LOCALCACHE}=GLO/Config/Geometry"
cp o2sim_geometry-aligned.root ${ALICEO2_CCDB_LOCALCACHE}/GLO/Config/GeometryAligned/snapshot.root
cp its_GeometryTGeo.root ${ALICEO2_CCDB_LOCALCACHE}/ITS/Config/Geometry/snapshot.root

Regenerating the TopologyDictionary

  1. Clusterization w/o tracking

First we need to use the clusterizer but ignoring the default TopologyDictionary, we built our own.

o2-its3-reco-workflow -b --tracking-mode off \
    --configKeyValues "HBFUtils.runNumber=303901;" \
    --ignore-cluster-dictionary --run
  1. Creating the TopologyDictionary
root -x -l ${ALIBUILD_WORK_DIR}/../O2/Detectors/Upgrades/ITS3/macros/test/CreateDictionariesITS3.C++
cp IT3dictionary.root ${ALICEO2_CCDB_LOCALCACHE}/IT3/Calib/ClusterDictionary/snapshot.root
  1. Rerun Clusterization with new TopologyDictionary
o2-its3-reco-workflow -b --tracking-mode off \
    --configKeyValues "HBFUtils.runNumber=303901;" \
    --condition-remap="file://${ALICEO2_CCDB_LOCALCACHE}=IT3/Calib/ClusterDictionary" \
    --run
  1. Check Clusters
root -x -l '${ALIBUILD_WORK_DIR}/../O2/Detectors/Upgrades/ITS3/macros/test/CheckClustersITS3.C++("o2clus_its.root", "o2sim_HitsIT3.root", "o2sim_geometry-aligned.root", "IT3dictionary.root")'
root -x -l '${ALIBUILD_WORK_DIR}/../O2/Detectors/Upgrades/ITS3/macros/test/CompareClustersAndDigits.C++("o2clus_its.root", "it3digits.root","IT3dictionary.root", "o2sim_HitsIT3.root", "o2sim_geometry-aligned.root")'
root -x -l '${ALIBUILD_WORK_DIR}/../O2/Detectors/Upgrades/ITS3/macros/test/CheckClusterSize.C++("o2clus_its.root", "o2sim_Kine.root", "IT3dictionary.root", false)'

Using external generators based on AliRoot

It is also possible to simulate heavy-ion collision using external generators based on AliRoot. In this case, it is necessary to load both O2 and AliROOT (the order is important):

alienv enter O2/latest AliRoot/latest

After that, the option -g external must be used and the file with the definition of the generator and the function to be used must be provided as parameters of the workflow:

o2-sim -j 1  \
-n 10 -g external \
--configKeyValues "Diamond.width[2]=6.;GeneratorExternal.fileName=hijing.C;GeneratorExternal.funcName=hijing(5020, 0, 20)"

The file hijing.C can be found here.