O2 Notes

I am working on this in my WORK/ALICE/O2/ directory in my computer.

Some useful links

• See chapter 4 of Matteo’s PhD thesis.

• Default tracking configuration parameters here.

• We went in detail over this code

  • Three steps:

    1. combinatorial (trackletting). Tracklets are formed from clusters in two layers. In this step, we find all the tracklets (from layers 0 and 1, and layers 1 and 2).

    2. tracklet selection. In this step we check which tracklets formed with layers 0-1 are aligned with those formed from layers 1-2. After the confirmation, we keep the tracklet from layers 0-1 (i.e. we don’t refit or anything. The tracklets from the outer layers are just for confirmation).

    3. compute vertices.

Simulations for ITS studies:

First do:

alienv enter O2sim/latest-o2

Running the simulation (generating particles and propagating them through Geant)

o2-sim -n 10000 -m PIPE ITS -g pythia8pp -e TGeant4 -j 2

Then we should run the digitization:

o2-sim-digitizer-workflow

Finally run the reconstruction:

o2-its-reco-workflow  --trackerCA --tracking-mode sync --configKeyValues "fastMultConfig.cutMultClusLow=-1;fastMultConfig.cutMultClusHigh=-1;fastMultConfig.cutMultVtxHigh=-1;ITSVertexerParam.phiCut=0.5;ITSVertexerParam.clusterContributorsCut=3;ITSVertexerParam.tanLambdaCut=0.2;;"

Scripts Matteo recommended to see how the data is accessed

O2/Detectors/ITSMFT/ITS/macros/test/CheckTracksCA.C

O2/Detectors/ITSMFT/ITS/macros/test/CheckVertices.C

Meeting with Matteo Concas on April 3, 2023:

Steps to install O2:

1. Install aliBuild and prerequisites described in analysis tutorial page: https://alice-doc.github.io/alice-analysis-tutorial/building/prereq-macos.html

2. Get both O2DPG and O2 in development mode:

git clone https://github.com/AliceO2Group/AliceO2.git O2
git clone https://github.com/AliceO2Group/O2DPG.git O2DPG

1. Initialize the environment:

aliBuild init

1. Build:

aliBuild build O2sim --defaults o2 -d