Multiple scattering
Multiple scattering model
GEANT4 uses a new multiple scattering model which simulates the
scattering of the particle after a step, computes the mean path length correction
and the mean lateral displacement.
The main features of the model
are described in the Characteristic features part:
multiple scattering.( talk in ps
, talk2 in ps )
Geometry
The geometry is a thin layer of homogeneous material,
the incident particle is an electron or proton.
This simple setup can be seen here
for the case of 6.56 MeV proton in 92.6 micrometer thick silicon detector,
where there are 10 events superimposed.
The protons are visualised as blue tracks,
the electrons (delta rays) as red tracks.
Some results
- 15.7 MeV electron , 18.66 mg/cm2 gold foil :
Geant4/Geant3/data comparison
The number of simulated events is 1 000 000
the experimental data are from A.O.Hanson et al. Phys.Rev. 84 (1951) 634.
- 6.56 MeV proton , 92.6 micrometer silicon :
Geant4/Geant3/data comparison
The number of events is 100 000
The experimental data have been taken from J.Vincour and P.Bem
Nucl.Instr.Meth. 148. (1978) 399.
- 70 GeV/c proton , 4.005 mm aluminium :
Geant4/Geant3/data comparison
1 000 000 simulated events.
The experimental data are from G.Shen et al. -
Phys.Rev. D20. (1979) 1584.
In this experiment the 1/e width of the angle distribution was measured for
high energy particles.
The width of the GEANT4 distribution is not far from the experimental value,
while GEANT3 does not reproduce the data:
the direction of the proton does not change at all
in most of the cases (there are 1851 "scattered" protons only out of
1 000 000 incoming protons).
The plot shows the scattering coming from the electromagnetic
interactions of the primary protons, the hadronic interaction
was "switched off" in the simulation.
The code of this example is in
geant4/examples/extended/electromagnetic/TestEm5
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