g4sim

Simulation toolkit based on Geant4 and ROOT

#1. Installation ##Prerequirements:

1. CMake installed

   If CMake if not provided by your package manager, you can visit CMake for source code then install CMake in this way:

   cd CMake
   ./bootstrap
   ./configure --prefix=path/to/CMake
   make
   make install
   

2. Geant4 installed
   Geant4
   If you want a UI with QT & OpenGL, please configure while installation. You can follow this way:

   cmake -DCMAKE_INSTALL_PREFIX=path/to/Geant4\
   	  -DGEANT4_INSTALL_DATA=ON\
   	  -DGEANT4_USE_GDML=ON\
   	  -DGEANT4_USE_G3TOG4=ON\
   	  -DGEANT4_USE_QT=ON\
   	  -DGEANT4_USE_OPENGL_X11=ON\
   	  -DGEANT4_USE_RAYTRACER_X11=ON\
   	  -DGEANT4_INSTALL_EXAMPLES=ON\
   	  -DGEANT4_USE_SYSTEM_CLHEP=ON\
     		  path/to/Geant4-source
   make
   make install
   

   CLHEP and XERCES are required by Geant4. If they are not installed in standard directories, please specify:

   	  -DCLHEP_ROOT_DIR=path/to/CLHEP -DXERCESC_ROOT_DIR=path/to/XERCES
   

3. ROOT installed
   ROOT
   You can install ROOT in this way:

   cd root
   ./configure --enable-opengl\
             --enable-soversion\
             --enable-mathcore\
             --enable-mathmore\
             --enable-gdml\
             --enable-python\
             --enable-roofit\
             --enable-minuit2
   make
   

   If you met an error saying mathmore is not installed, a possible reason can be that GSL is not installed in a standard directory. You can configure with:

   --with-gsl-incdir=path/to/GSL/include --with-gsl-libdir=path/to/GSL/lib
   

##Install:

cd cmake
cmake .
make

#2. How to use ##Prerequirements:

1. Geant4 environment is set already.

   If not, then

   source /path/to/geant4/bin/geant4.sh
   source /path/to/geant4/share/Geant4-*/geant4make/geant4make.sh
   

2. ROOT environment is set already.

   If not, then

   source /path/to/root/bin/thisroot.sh
   

3. Your working directory has been created.

   Example is a working directory for a simple simulation to show how g4sim works. It also serves as a template for someone who want to build another simulation.

4. g4sim basic environment is set already.

   If you have already set environment variable $MYG4SIMROOT to the directory of g4sim, you can go to working directory, otherwise you will need to

   	source env.sh  
   

   Then go to your working directory and set environment:

   	cd alcap # or whatever working directory
   	source setenv.sh
   

##To Start:

g4sim [macros/run.mac]             # Choose any Geant4 macro file you want.
                                   # without macro file it would enter interactive mode.  

A figure to show how it works:

##To Configure:
By default (set in setenv.sh):

GENFILEROOT=gen/gen_mum_up
GEOCARDROOT=geometry_1217
OUTCARDROOT=output/output_default

With this default environment set already you can start simulation with /run/beamOn XXX immediately.
###GENFILEROOT:
We provide couple ways to configure:

1. Use another configure file

Currently we have these optional choices:

gen_mum_up      # Generate muon from upstream before MuPC
gen_gam_tgt     # Generate gamma from target position

You can either set the environment variable $GENFILEROOT or use macro command /g4sim/gun/ResetGen gen/gen_mum_up in Geant4 session to reset generator setting based on this given configure file.

2. Modify some parameters using macro commands

Here are a couple of macro commands we can use: