OMSim is a Geant4 framework for simulating optical modules of the IceCube Observatory. It comprises multiple modules for different studies such as background investigations with radioactive decays and sensitivity analyses. These modules share common files (in the "common" folder) that define, for example, geometries of modules and PMTs, as well as material properties.

For more information, please refer to our documentation.

For the latest updates and information, check our GitHub repository. If you need assistance or want to report problems, please open an issue on our GitHub page or contact the maintainers directly.

Installation

Installing Geant4

Install Geant4 following the guide provided by CERN. OMSim is currently optimised for Geant4 11.3.0.
For visualisation tools, include the following CMake options:

-DGEANT4_INSTALL_DATA=ON -DGEANT4_USE_GDML=ON -DGEANT4_USE_OPENGL_X11=ON -DGEANT4_USE_QT=ON -DGEANT4_USE_RAYTRACER_X11=ON -DGEANT4_USE_XM=ON

Note: Do not change GEANT4_BUILD_MULTITHREADED to OFF, as OMSim supports multithreading.
Source the Geant4 library and add this to your .bashrc, where "YOUR_G4_INSTALL" is the path to the install folder of Geant4 in your system:
source YOUR_G4_INSTALL_PATH/bin/geant4.sh

Installing Dependencies

Install the required dependencies using:

sudo apt-get -y install libxerces-c-dev libxmu-dev libxpm-dev libglu1-mesa-dev qtbase5-dev libmotif-dev libargtable2-0 libboost-all-dev libqt53dextras5 libfmt-dev libspdlog-dev

Installing ROOT

Download the latest ROOT binary from ROOT's official website (e.g., version 6.32.08 at the time of writing), or compile from source.
Add the following to your .bashrc for convenience:
export ROOTSYS=YOUR_ROOT_PATH

source $ROOTSYS/bin/thisroot.sh

Compiling OMSim

Clone this repository:
git clone https://github.com/icecube/OMSim.git

cd OMSim
Create a build directory:
mkdir build && cd build
Run CMake:
cmake ..

If CMake doesn't find Geant4, use the following, where "YOUR_G4_INSTALL" is the path to the install folder of Geant4 in your system:
cmake -DGeant4_DIR=YOUR_G4_INSTALL/lib/Geant4-11.2.2/ ..
Compile the project:
make -j$(nproc)

Available studies

OMSim has been utilized in a range of studies, each simulating unique physics, thereby necessitating distinct Physicslist/analysis setups. In this repository, we have compiled a selection of these studies, each contained within its own folder and accompanied by its own main file. Currently available:

Effective area: calculates the effective area of the optical modules/PMTs.
Radioactive decays: simulates radioactive decays within the glass of the pressure vessel and the PMT glass. Essential for understanding the primary background of optical modules. Requires Geant4 version 11.3.0
Supernova studies: used for the development of an improved SN trigger for IceCube using multi-PMT modules.

Customising Compilation

To exclude certain studies from compilation, edit the simulations/CMakeLists.tx file and comment out the unwanted add_subdirectory() calls before running CMake.

Troubleshooting

Depending on your system configuration, you may encounter compilation errors related to missing dependencies. For example, after running:

make -j 4
[  2%] Linking CXX executable ../../OMSim_effective_area
/usr/bin/ld: warning: libtbb.so.2, needed by ...

you can resolve this by installing libtbb2:

sudo apt install libtbb2

Please report any other related errors to the #omsim Slack channel or open an issue so we can track them.

Another known issue is that Anaconda3 installations can interfere with library paths. You can temporarily disable Anaconda by renaming its directory before compiling:

mv /path/to/anaconda3 /path/to/anaconda3_temp

Check carefully your cmake .. and make output to identify and resolve potential issues and consult your system administrator if applicable. Please note that we cannot guarantee full support for all system configurations.

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