Introduction

This repository is meant as a collection and working area for stuff going into PID studies for the ALICE TRD. It is mainly a collection of my (Tom Dietel) personal work, but I might pull in other people's work as I see fit.

Some code has been (and will be) moved from here to AliRoot and AliPhysics, to be used in production.

In the following you will find some hints what some parts of the software are supposed to do.

Reconstruction [rec]

Reconstruct data (or simulated) files. This is e.g. necessary if you want to prepare some raw data files to play with raw data filtering.

full reconstruction: 'rec/rec.C'

This runs the full reconstruction. This script was taken from alien:///alice/cern.ch/user/a/alidaq/LHC13f/rec.C. The macro will produce write TRD digits as well as the standard output. The OCDB will be taken from CVMFS.

The easiest way to run reconstruction is to create a new directory, create a symlink raw.root in this directory with ln -sf /path/to/your/raw/file.root raw.root and run the reconstruction from there with aliroot -b -q -l path/to/rec.C

extraction of TRD digits from a raw file: rec/rec_digits.C

Reads a raw data file and extracts the TRD digits into a file TRD.Digits.root. Can be used to re-run the MCM emulator and for detailed PID and other studies.

Filtering [filter]

This part deals with raw data filtering for TRD PID studies. The purpose of this is to get a reasonable sample of raw data from high-pT electrons, that can be used to optimize the PID.

A large part of this is now available in AliPhysics, and this is mainly an example how to call these parts. The main work is done in the class AliTRDdigitsFilter (in $ALICE_PHYSICS/PWGPP/TRD/AliTRDdigitsFilter), which is instantiated by $ALICE_PHYSICS/PWGPP/TRD/macros/AddTRDdigitsFilter.C).

Analysis [ana]

This is an example analysis, which at the moment produces a spectrum of TRD tracks (and all tracks, for comparison), and an ADC spectrum for the TRD digits.

The analysis is run via the macro ana.C, which in turn loads analysis tasks either from Aliroot/AliPhysics, or from local directories. If you want to use a local analysis task, it must be accessible for gROOT->LoadMacro(), i.e. either be in the current working directory where you run the analysis, or you must make it available in some other way.

You can run the analysis in the same folder as the reconstruction was run (with rec/rec.C, see above). You can do this my symlinking all necessary files to the directory where the reconstruction produced its output: ln -sf path/to/ana/*.C path/to/ana/*.cxx path/to/ana/*.h .. Afterwards you can run the analysis with aliroot -b -q -l ana.C.