jeffersonlab / halla_comptong4

Hall A Compton Polarimeter Geant4 Code

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....

halla_comptong4's Issues

Implement Acc4 logic into PMT class

Add electron detector "Sensitive Detector" class

Add Compton mode to generate electrons/photons simultaneously

Once #3 is done, we need to add another option that will generate electrons and photons simultaneously (for special coincidence tests).

Add simple example on how to run

Could you update the README with information on how you would run the GUI or a test (100 event) simulation?

Check to see if it compiles and works with ROOT 6

Add Tungsten "Fingers" to Photon Detector Geometry

Change generator messenger to accept a string, rather than an int

With more generators to be added, it's getting harder to justify having an int represent the generator mode.

I think instead of using an int, we should now use a string, so that we can type things like:

/Compton/gun/mode ComptonPhotonMode

to produce Compton scattered photons. Currently, we use the number 1 to represent this mode.

Allow static compilation

Sometimes static linking is desirable, and we should be able to support it. This is specially true when we want to reduce reading of files/libraries on an NFS directory.

Stop generating separate random seed files

A feature that I used while debugging the code now seems to be kind of annoying, in that it saves the random seed every N entries.

I think it should instead save the random seed to either the ROOT file, or in one job specific file.

Add Dipole magnetic fields

Right now we can add constant fields. But would be nice to have the field maps included so that we can get synchrotron studies going for both phDet and eDet.

Add Electron Detector Geometry

Remove requirement on BOOST libraries

This one is a big one. But it might be a good idea to remove the requirement on the BOOST libraries.

Right now, BOOST is used to parse command line options and to parse auxiliary information from GDML files (right now, only color, which could easily be changed to not use boost at all!).

Add electron generator

In order to be useful for the Electron Detector, we need to also add an electron generator.

Add Compton Chicane geometry

Create GDML file containing the Compton chicane geometry.

Problems compiling with Geant4 10.2 due to changes in G4GDMLAuxPairType