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3.4 Run control and output

The execution control is performed in the GMAD input file through option and sample commands. How the results are recorded is controlledby the sample command. When the visualization is turned on, it is also controlled through Geant4 command prompt

3.4.1 option

Most of the options in bdsim are set up by the command

option, <name>=value,...;

The following options influence the geometry

     
     beampipeRadius    - default beampipe radius [m]
     beampipeThickness - default beampipe thickness [m]
     tunnelRadius      - tunnel Radius [m]
     boxSize           - default accelerator component size [m]
     
     

The following options influence the tracking

     
     deltaChord          - chord finder precision
     deltaIntersection   - boundary intersection precision
     chordStepMinimum    - minimum step size
     lengthSafety        - element overlap safety
     thresholdCutCharged - charged particle cutoff energy
     thresholdCutPhotons - photon cutoff energy
     randomSeed          - seed for the random number generator
                                  setting to -1 uses the system clock to generate the seed
     stopTracks          - if set, tracks are terminated after interaction with
                                  material and energy deposit recorded
     physicsList         - determines the set of physics processes used
     ngenerate           - number of primary particles fired when in batch mode
     nperfile            - number of events recorded per file
     nlinesIgnore        - number of lines to skip when reading bunch files
     synchRadOn          - turn on Synchrotron Radiation process
     srTrackPhotons      - whether to track the SR photons
     srLowX              - Sets lowest energy of SR to X*E_critical
     srLowGamE           - lowest energy of propagating SR photons
     minimumEpsilonStep  - minimum relative error acceptable in stepping
     maximumEpsilonStep  - maximum relative error acceptable in stepping
     deltaOneStep        - set position error acceptable in an integration steps
     prodCutPhotons      - standard overall production cuts for photons
     prodCutPhotonsP     - precision production cuts photons in element
     prodCutElectrons    - standard overall production cuts for electrons
     prodCutElectronsP   - precision production cuts electrons in element
     prodCutPositrons    - standard overall production cuts for positrons
     prodCutPositronsP   - precision production cuts positrons in element
     
     
     

For a more detailed description of how the option influence the tracking see Physics

3.4.2 beam

The parameters related to the beam are given by the beam command

beam, <name>=value,...;

The available parameters are:

     
     particle    - particle name, "e-","e+","gamma","proton", etc
     energy      - particle energy
     distrType   - type of distribution
     distrFile   - input bunch file
     

beam, particle="e+",energy=100*MeV, distrType="gauss";

3.4.3 sample

To record the tracking results one uses the sample

sample, range=<element>;

The sampling plane is then inserted before <element>

Example :

     sample, range=d;

Cylindrical sampler of length l is put around element <element> at distance <r> with the command

sample, range=<element>, r=r0, l=l0;

3.4.4 use

use command selects the beam line for study

     use, period=l1,range=q1/q2