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0001 Example GB07 : leading particle biasing
0002 ----------------------------------------
0003
0004 This example illustrates how to use the leading particle biasing option.
0005
0006 It uses the G4BOptnLeadingParticle biasing operation located in:
0007
0008 source/processes/biasing/generic ,
0009
0010 and defines the following biasing operation to handle it:
0011
0012 GB07OptrLeadingParticle.
0013
0014 As a reminder, the generic biasing scheme consists of a G4VBiasingOperator
0015 that takes decisions on what sort of biasing technique to be applied. The
0016 techniques are called biasing operations, represented by the G4VBiasingOperation
0017 class. The operator is attached to a logical volume in which the biasing must
0018 happen. Decisions are made on requests of the G4BiasingProcessInterface process
0019 that messages the operator when the track is travelling in the volume. To equip
0020 the phyics list with this process, the G4GenericBiasingPhysics physics
0021 constructor is used. In this example, several processes -to which the technique
0022 is applied- are wrapped by this process to control their final state production
0023 for applying the biasing technique.
0024
0025
0026 Geometry:
0027 ---------
0028
0029 The geometry is simply :
0030 - a volume in which the biasing occurs and to which an instance of
0031 GB07OptrLeadingParticle is attached,
0032 - a thin volume placed after the above volume, that is used to tally the
0033 particles exiting biasing volume.
0034 - a sensitive detector is attached to the thin volume to simply print the
0035 particles entering here. In particular the statistical weight is printed,
0036 this one is obtained by:
0037
0038 w = track->GetWeight() ;
0039
0040
0041 Biasing configuration:
0042 ----------------------
0043
0044 The particle types and processes under the leading particle biasing are
0045 visible in the main program exampleGB07.cc, these are:
0046
0047 pi+ and pi-, inelastic process,
0048 proton and anti-proton, inelastic process,
0049 neutron, inelastic and capture processes,
0050 anti-neutron, inelastic process,
0051
0052 gamma, conversion and photonNuclear processes,
0053 electron, electronNuclear process,
0054 positron, annihilation and positronNuceal processes,
0055
0056 pi0, decay process.
0057
0058 For the inelastic and lepto/gamma-nuclear processes, leading particle is applied in a rather
0059 classical way:
0060 - keep the leading particle,
0061 - keep one particle of each species (particles and anti-particles are considered a one
0062 species, and all hadrons with Z>=2 are counted as one species too).
0063 For e+, e-, gamma and pi0 processes (which means in practice main conversion, annihililation
0064 and pi0 decay processes), the leading particle is kept, and the companion track(s) is(are) randomly
0065 kept/killed under a Russian roulette, with a 2/3 killing probabilty. See
0066 GB07BOptrLeadingParticle::StartTracking( ... ) for this killing probability setting.
0067
0068
0069 Running the program:
0070 --------------------
0071
0072 The program can be run in batch or interactive mode and has the following options:
0073
0074 in batch:
0075 ./exampleGB07 [-m macro ] [-b biasing {'on' = default,'off'}]
0076 or
0077 ./exampleGB07 [macro.mac]
0078 interactive:
0079 ./exampleGB07 [-b biasing {'on' = default,'off'}]
0080
0081
0082
0083
0084
