Gabriele Cosmo
50 lines
1.9 KiB
Plaintext
50 lines
1.9 KiB
Plaintext
Example GB01 : cross-section biasing
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This example illustrates how to bias process cross-sections.
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Generally speaking, the scheme consists of a G4VBiasingOperator that takes
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decisions on what sort of biasing is to be applied. The operator makes these
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decision on requests of the G4BiasingProcessInterface process. This process
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wraps an actual physics process and asks to the operator about what sort of
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biasing it should apply. This operator selects G4VBiasingOperation objects that
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implement the actual biasing content.
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In the present case, the G4VBiasingOperation objects are
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G4BOptnChangeCrossSection
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instances. This class is defined in processes/biasing/generic.
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A first operator is defined to handle the case of one particle:
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GB01BOptrChangeCrossSection .
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The change of cross-section is generally speaking a change of process occurence.
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G4BOptnChangeCrossSection objets are then selected in the method:
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G4VBiasingOperation* ProposeOccurenceBiasingOperation(...)
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of the GB01BOptrChangeCrossSection operator.
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To allow this same cross-section change to be applied to several particle
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types, an other operator is defined
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GB01BOptrMultiParticleChangeCrossSection
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which holds one GB01BOptrChangeCrossSection per particle type, and which
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delegates then everything to it.
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The geometry is simple : a single volume to which an instance of
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GB01BOptrMultiParticleChangeCrossSection is attached to.
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The wrapping of physics processes by G4BiasingProcessInterface processes
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is simply handled by the G4GenericBiasingPhysics physics constructor, as shown
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in the main program.
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Then, at whatever level (stepping action, or sensitive detector) the
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statistical weight of the track can be obtained as:
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w = track->GetWeight() ; |