/star-fwd-integration

Primary LanguageC++

star fwd software integration on RCF

This code provides a snapshot of the star-sw development of the STAR forward tracking and detector simulator software.

TL;DR.

  1. checkout the github repo : git clone https://github.com/jdbrice/star-fwd-integration.git
  2. run starver dev, then run ./rcf-build.sh to build the code
  3. make a simulation dataset : starsim -w 0 -b tests/testg.kumac nevents=1000 ntrack=1 etamn=2.5 etamx=4.0 ptmn=0.2 ptmx=1.0
  4. run the forward tracking test with : source rcf-env.sh then root4star -b -q -l tests/fast_track.C
  5. Optional: check test.root for the debug output of the forward tracking, e.g. "PtRes" histogram shows average pT resolution.

What is included?

StRoot
|-StFwdTrackMaker (Maker for running forward tracking)
|-|-StFwdTrackMaker.h
|-|-StFwdTrackMaker.cxx
|-|-XmlConfig/ (See: https://github.com/jdbrice/XmlConfig )
|-|-include/Tracker (forward tracking package)
|
|-StFstSimMaker (Simulator for the forward silicon tracker)
|-|-StFstFastSimMaker.h
|-|-StFstFastSimMaker.cxx
|
|-StFttSimMaker (Simulator for the forward sTGC tracker)
|-|-StFttFastSimMaker.h
|-|-StFttFastSimMaker.cxx

StFwdTrackMaker

This is the main package for running forward tracking through StRoot. The package consists of a "maker" that interfaces with the STAR environment and can be run as part of the StChain. The StFwdTrackMaker and internal tracking framework maintain a clear separation of concerns. From the perspective of the StFwdTrackMaker the tracking package is meant to be a "black box" - space points from detector hits are fed into it, and track seeds / fit tracks are output and the internal implementation is irrelavent.

What the StFwdTrackMaker does:

  • StFwdTrackMaker loads detector hit data
    • directly from GEANT for MC level tracking performance
    • from the StEvent hit collections
  • Provides primary vertex information (currently only MC PV information is provided)
  • Writes track info into StEvent

What the tracking package does:

  • Once, during initialization
    • loads magnetic field map from StarMagField
    • sets up geometry for tracking in material
  • Each event
    • finds track seeds
    • fits tracks using GenFit
    • passes back a list of fit tracks

StFstSimMaker

This package provides simulators for the forward silicon tracker. Currently only the "fast" simulator is included. The fast simulator processes GEANT hits stored in the g2t_fsi_hit table. The primary function of this package is to digitize the GEANT hits onto the R-phi strips of the silicon sensor layout. The hits are stored into StRndHit objects and the covariance matrix is computed according to the local geometry of the hit.

StFttSimMaker

This package provides simulators for the forward silicon tracker. Currently only the "fast" simulator is included. The fast simulator processes GEANT hits stored in the g2t_stg_hit table. The primary function of this package is to digitize the GEANT hits onto the strip layout of the sTGC module geometry. The hits are stored into StRndHit objects and the covariance matrix is computed according to the nominal XY resolution of 100 microns. Since the sTGC is essentially a sandwich of two 1D detectors, ghost hits are present at the intersection of lit strips. These ghost hits are computed according to XY strips and added to the hit collection.

Note about Fast Simulators

Since the fast simulator is meant to be the simplest response simulator, they are essentially complete. However a few things will change in the future:

  • StRndHit will be replaced a dedicated hit object for fst type hits.
  • The StRndHitCollection will be replaced with a dedicated hit collection for fst type hits

These updates to StEvent are being worked on in parallel (the addition of dedicated hit types and collections). The important things to note are that 1) this code already works with the StEvent in dev, 2) StEvent can be updated separately with no conflicts, 3) The update will be atomic/transparent since no other code currently depends the StRndHit / StRndHitCollection.

Building the packages on RCF

The file build.sh invokes cons with additional flags to provide header files for the external dependencies of Genfit and KiTrack. Build with:

starver dev
./rcf-build.sh

This modified cons call just adds include paths via the EXTRA_CPPPATH variable. Currently the header files for the dependencies are found here:

/star/data03/pwg/jdb/FWD/cmake/star-install-SL20c-64-Release/sl74_x8664_gcc485/include/

Running tests

Generate simulation file as input

A simple kumac is included for generating single particle events for testing. generate an fzd file with:

starsim -w 0 -b tests/testg.kumac nevents=1000 ntrack=1 etamn=2.5 etamx=4.0 ptmn=0.2 ptmx=1.0

Running the forward tracking

The fast_track.C script is a basic example of how to run the two fast simulators and the forward tracking package. It can be run with:

source rcf-env.sh
root4star -b -q -l tests/fast_track.C

This will produce a number of output files for evaluating the fast simulators and the tracking. Specifically one may look at "test.root" which contains the forward tracking output. The histogram "FitStatus" shows a summary of the fitting steps. The histogram "PtRes" shows the pT resolution.

Prebuilt dependencies

The GenFit2 and KiTrack libraries are built with CMAKE. The prebuilt shared libraries are here:

/star/data03/pwg/jdb/FWD/cmake-test/star-install-SL20c-32-Release/sl74_gcc485/lib/

built in 32-bit release mode.

NOTES:

As of this writing, the code builds on RCF but I do not have a setup for running the forward tracking yet - since I need to build Genfit and KiTrack in RCF (32bit).