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        GATE - UserSpectrum source
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Authors: S. NICOLAS, Y. Perrot, L. Maigne*
Laboratoire de Physique Corpusculaire de Clermont-Ferrand, CNRS/IN2P3 - Clermont University, France
* Corresponding author: maigne@clermont.in2p3.fr


---> Description

This example shows how to use the different modes of UserSpectrum source (Discrete Spectrum (mode 1), Histogram (mode 2) and Linear interpolation spectrum (mode 3)).

---> Set-up

The geometry consists in a world volume made of liquid water including one box (MainBox) made of liquid water.
Three isotropic point sources centered in the MainBox are created:
one gamma source emitting particles from a discrete spectrum (mode 1),
one electron source emitting particles from a histogram (mode 2)
one electron source emitting particles from a linear interpolation spectrum (mode 3).

Source descriptions are defined with txt file format:
The first line describe the mode value and the minimum energy. 
Following lines described energy(MeV) and probability values.

Text files are located in the data repository.

---> Physics

The Geant4 Standard option 3 physics list is assigned to the world volume and the MainBox volume with a cut of 10 kilometers to avoid secondary particles.
A KillActor (allocated to the MainBox) is used to kill primary particles when they are created (before all interactions).


---> Output

All spectrum sources are saved with an EnergySpectrumActor.
To analyse the spectrum with ROOT, use the plot.C macro file.


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