STAR Tutorial <- click

Alexandr Prozorov

For successfull running on Github Codespaces one can submit an application for Free Github Education benefits.

This is an example analysis of StPicoDst:

St stands for STAR, all classes start from it
Pico means the tree data format where only small number of numerous qualities are saved, exist also Micro and Mini,
Dst means Data Summary Table)

It is based on Grigory’s presentation on PicoDst 2019

Introduction

The starver corresponds to the latest version star pro with compiler gcc4.85 and ROOT 5.34 version.

STAR uses cons command to compile. This is similar to compiling projects using Make file or performing g++ command with additional libs within complex C++ projects (whic STAR is). The cons command will:

create a directory .sl7X_gccXX where all compiled libraries will go which are used in your project
perform compilation of all your files with .cxx(important!) and connected headers .h under StRoot directory.

What this tutorial about?

It will show how StRoot folder is used to compile your project.
The analysis macro will create a file with user TTree and QA Histograms
The user defined TTree actually consists of classes MyTreeEvent.h and MyTrack.h
There is a second standalone macro which does not need any STAR infrastructure - only meantioned header files MyTreeEvent.h and MyTrack.h and can be further used for analysis on personal latptop or batchfarm.

Run instructions:

First, you’ll need to enter the STAR container, for that, type:
```
star-shell
```
To compile a project, perform cons command
```
cons
```
Now, one can run event analysis macro using without(!) compilation (not using + sign at the end)
```
root -l -b -q macros/runPicoDstAnalysisMaker.C
```
It will create a .root file with your TTree and some QA histograms. If you are interested what are these ROOT flags:
- -l - no splash screen
- -b - stands for batchmode (no pictures showed),
- -q - quit after executing.
Now, one can perform your analysis on this newly created TTree with compiled (!) macro - notice + at the end
```
root -l -b -q macros/readMyTreeEvent.C+
```

Some old presentation on DST tutorials:

Introduction to PicoDst (Grigory Nigmatkulov, 2019)
Starting Data Analysis on STAR (Samantha Brovko, 2011)
A common-MuDst tutorial (Sergey Panitkin, 2003)

Remark: Running on your own laptop

In case you want to enter and run STAR container on your own laptop:

You need to install either Docker engine or Apptainer (singularity). For simplier Apptainer (singularity) installation:

sudo apt update
sudo apt install -y software-properties-common
sudo add-apt-repository -y ppa:apptainer/ppa
sudo apt update
sudo apt install -y apptainer

And then run commands:
```
git clone https://github.com/aprozo/star-tutorial.git
cd star-tutorial
apptainer run docker://ghcr.io/star-bnl/star-sw:main-root5-gcc485 bash -l
```
Important!
Do not forget to comment in your ~/.bashrc sourcing your local Root installation (source /path/thisroot.sh), otherwise there will be a conflict of 2 ROOT versions: one - from your local installation, another - from STAR container.

You may also create a shortcut for star-shell using code below:

mkdir -p ~/.local/bin && cat >~/.local/bin/star-shell <<'EOF'
#!/usr/bin/env bash
apptainer run  docker://ghcr.io/star-bnl/star-sw:main-root5-gcc485 "$@"
EOF
chmod +x ~/.local/bin/star-shell
grep -qxF 'export PATH="$HOME/.local/bin:$PATH"' ~/.bashrc || echo 'export PATH="$HOME/.local/bin:$PATH"' >>~/.bashrc
export PATH="$HOME/.local/bin:$PATH"