Welcome to G4PlasticDetector

G4PlasticDetector is an application based on the Geant4 Monte Carlo toolkit for simulating the response (i.e. geometric factor, efficiency, energy migration matrix, etc) of an Eljen Technologies M550-20x8-1 Plastic Scintillator (EJ-204) 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/G4PlasticDetector : This is the source directory and is a clone of the code from this GitHub
• $G4WORKDIR/G4PlasticDetector-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 G4PlasticDetector-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/G4PlasticDetector; sudo make -j8; ./G4PlasticDetector

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 EJ-204 plastic scintillator 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 EJ-204 plastic scintillator 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.