GEANT4 Simulation for The Hall A Compton Polarimeter

Simulation package used to extract an electron beam polarization via detection of Compton Scattered photons and/or electrons.

Getting Started

These instructions are meant to provide a very quick guide to compiling and running a sample simulation using the PbWO4 detector used during the DVCS 2016 running period.

Requirements

• Geant4 > 10.0
  • With GDML, Qt and CLHEP support build int.
  • For Geant4 > 10.2, a compiler with C++11 support is also needed.
• BOOST libraries
• cmake > 2.8
• git (for contributing to the development process)

Setup your build environment

For simplicity, these instructions will use a directory structure such that the code will be inside one directory and the compilation will happen on another. For example:

cd $HOME
mkdir HallACompton
cd HallACompton
mkdir build

Downloading and Compiling

You can get the latest copy of the software form Github at https://github.com/JeffersonLab/HallA_ComptonG4. The recommended method of getting a copy is to use git to clone a fresh copy of the master branch. The path that you will use depends on whether you have a github account and intend on contributing to the development process, or you do not have a github account.

If you have a github account, you can use SSH authetnication with any of SSH keys you have added to your account. Then to get a copy of the HallA_ComptonG4 code, you use:

cd $HOME/HallACompton
git clone [email protected]:JeffersonLab/HallA_ComptonG4.git

Alternatively, if you do not have an account, or, you cannot use SSH due to restrictions on your network, you can get the code from HTTPS like so: a copy of the code, like so:

cd $HOME/HallACompton
git clone https://github.com/JeffersonLab/HallA_ComptonG4.git

Building the software

After you have used one of the two methods above to get a copy of the code, you should have two directories in $HOME/HallACompton: build and HallA_ComptonG4.

We use cmake to build the software, which requires the use of a different (and clean) directory than the source code. The recommended method is to use a directory outside the HallA_ComptonG4 directory containing the github code. In our example directory structure, we will build the code in $HOME/HallACompton/build and the actual source code will live in $HOME/HallACompton/HallA_ComptonG4.

Then to build the code we use:

## Change into the build directory
cd $HOME/HallACompton/build
## Use cmake to configure the build (needs to be re-run after adding
## any files to the source tree)
cmake -D CMAKE_BUILD_TYPE=RelWithDebInfo ../HallA_ComptonG4
## Build the actual code
make
## Optionally, you can install the software in a common location
## (you can specify the install location by adding
##      -D CMAKE_INSTALL_PREFIX=/path/to/install/location
## right before the ../HallA_ComptonG4 part.
make install ## Optional

Status:

So far, only the photon detector is enabled. But electron detector will be added soon....