Welcome to G4LaBr3Detector

G4LaBr3Detector is an application based on the Geant4 Monte Carlo toolkit for simulating the response (i.e. geometric factor, efficiency, energy migration matrix, etc) of a Saint Gobain BrilLanCe 380 LaBr3(Ce) detector.

Build Notes

To build this application, you should have a working version of CMake and Geant 4.10.3.p01 or higher.

Geant4: https://geant4.web.cern.ch/geant4/ CMake: https://cmake.org/

I recommend setting up your directory structure as follows:

• $G4WORKDIR/G4LaBr3Detector : This is the source directory and is a clone of the code from this GitHub
• $G4WORKDIR/G4LaBr3Detector-build : Contains directories and files for each build. This directory also contains the executable files and example macros.

The simulation works both in sequential and in multi-threaded (MT) modes of Geant4. However, a significant speedup can be achieved by running the simulation in MT mode.

Steps to compile:

Step 1 - Source the Geant4 environment setup script

source /opt/Geant4/geant4.10.03.p01-install/bin/geant4.sh

Step 2 - Create the build directory and navigate to it

mkdir G4LaBr3Detector-build && cd $_

Step 3 - Setup CMake, make the build, and run the build

sudo cmake -DGeant4_DIR=/opt/Geant4/geant4.10.03.p01-install/lib/Geant4-10.3.1/ ~/G4WORK/G4LaBr3Detector; sudo make -j8; ./G4LaBr3Detector

To recompile, I typically just re-run the command in Step 3

Scoring Physical Quantities

Scoring of physical quantities is carried out through the G4MultiFunctionalDetector which allows multiple primitive scorers to be assigned to a single volume. In this simulation, a G4MultiFunctionalDetector is assigned to the sensitive volume of LaBr3 crystal and the source volume. The value recorded by the primitive scorers is collected on event-by-event basis enabling calculation of the detector response.

The primitive scorer(s) registered for the sensitive volume of LaBr3 crystal are:

• G4PSEnergyDeposit

The primitive scorer(s) registered for the source volume are custom kinetic energy scorers:

• G4PSIncidentKineticEnergy

During a run, the data collected on an event-by-event basis is histogrammed into five logarithmically binned ROOT histograms.

• The first histogram, labeled "Source Fluence (Gamma)", records fluence and kinetic energy of incident gamma-ray source particles.
• The second histogram, labeled "Source Fluence (Electron)", records fluence and kinetic energy of incident electron source particles.
• The third histogram, labeled "Detector Measured Spectrum", records the measured or deposited energy in the detector.
• The fourth histogram, labeled "Energy Migration Matrix (Gamma)", records a 2D histogram of the true kinetic energy versus measured/deposited energy in the detector from gamma-rays.
• The fifth histogram, labeled "Energy Migration Matrix (Electron)", records a 2D histogram of the true kinetic energy versus measured/deposited energy in the detector from electrons.