Geant4 - splitting
Authors: J. A. Ramos-Mendez*, B. A. Faddegon
Department of Radiation Oncology, University of California San Francisco
* Corresponding author, email to joserm84@gmail.com
This example is provided by the Geant4-DNA collaboration.
These processes and models are further described at:
geant4-dna.org">http://geant4-dna.org
Any report or published results obtained using the Geant4-DNA software shall
cite the following Geant4-DNA collaboration publications:
Phys. Med. 31 (2015) 861-874
Med. Phys. 37 (2010) 4692-4708
If use this example, please cite
J Ramos-Mendez, et. Al. Phys. Med. Biol. 62(15), 5908-5925, (2017) DOI: 10.1088/1361-6560/aa7831
---> 1. A brief description
The splitting example uses variance reduction to improve the computational
efficiency of calculations of ionization cluster size distributions. Ionization
events are scored in a nanoscaled cylinder. Ionized electrons generated by
the first generation of secondary electrons are split, i.e. new clone electrons
are generated, labeled and propagated. The label is used to classify those
new particles as if they were produced by independent histories to avoid
overlapping of tracks at final analysis. The splitting is performed only
if the ionization event occurred in the cylinder.
Geant4-DNA processes are used.
The example package contains:
- source files (src, include)
- README
- .in, plot.C and visualization macro files
**** 2. Set-up.
The geometry is a nanoscaled cylinder centered in the world. The medium is
water everywhere. The dimensions can be defined with
/detector/diameter 6 nm
/detector/length 10 nm
User can define the split number (default is 1, i.e. no split)
with:
/vrt/numberOfSplit 10
**** 3. How to run the example.
In interactive mode, run:
./splitting
Idle> /control/execute vis.mac
In batch mode , run:
./splitting run.mac
To get visualization, make sure to uncomment the #/control/execute vis.mac line in the macro.
**** 4. The physics
This example shows:
- how to use the Geant4-DNA processes,
- how to implement the splitting via G4WrappedProcess
- how to set the splitting in specific region
- how to propagate new track information to secondary particles
A simple electron capture process is also provided in order to kill electrons
below a chosen energy threshold, set in the Physics list.
Look at the PhyscisList.cc file.
**** 5. Simulation output
The output results consists in two histograms in root format
- the energy deposit in the cylindrical target
- the frequency distribution of ionization cluster size
NOTE: Every time a value is added to a ROOT histogram, it contributes to the statistics.
For this example, to correct estimate the uncertainties is recommended to split the simulation into
several jobs and to calculate the statistics from them: batch mode. Otherwise, the statistical
uncertainty may be underestimated.
**** 6. Contacts
If you have any questions or wish to notify of updates and/or modification please contact:
J. Ramos-Mendez at joserm84@gmail.com
**** Acknowledgments :
Sebastien Incerti (CNRS) for its guidance
...
SEE ALSO: README
