&DRIFT: DRIFT


EDGE

  Indicates that the drift line calculation will begin at some of
  the boundaries of the drift area as set by AREA.

Additional Information on:

  • sides
  • lines

  • WIRE

      Requests that the electrons or ions start to drift from the
      surfaces of the wires that have been SELECTed.
    
      Electrons are usually not produced near the wires and they
      are therefore drifted by default 'in reverse', i.e. with a
      positive charge. The resulting plot shows the origin of all
      electrons that can end up on the wire.
    
      Since ions are normally produced near the wire surface, they
      are drifted in their usual mode, i.e. with a positive charge.
      The resulting plot therefore shows where ions go that are
      produced in an avalanche at the wire.
    
      To modify this behaviour, i.e. to study electrons drifting away
      from wires that repel electrons and ions drifting away from
      wires that attract ions, use the POSITIVE and NEGATIVE options.
    

    Additional Information on:

  • lines

  • TRACK

      Indicates that the drift line calculation will begin on the track.
    
      The appearance of the resulting plot depends to a large extent
      on the format of the TRACK command that you have used:
      - electron or ion drift lines from a user determined number
        of regularly spaced points along a track (TRACK FIXED)
      - electron drift lines from randomly distributed points along
        the track, including cluster formation (TRACK EXPONENTIAL)
      - electron drift lines from the points where a particle
        traversing the chamber ionised the gas, including or not
        delta and Auger electrons, photo ionisation and multiple
        scattering (TRACK HEED)
    
      Although permitted, the ION option has no meaning used together
      with the latter two TRACK formats.
    

    Additional Information on:

  • graphs
  • MARKER

  • ZEROS

      Indicates that the drift line are calculated from the zeros of the
      electrostatic field, both in the attracting and in the repelling
      directions. The ELECTRON/ION and POSITIVE/NEGATIVE settings are
      ignored. This choice is useful when you're determining the precise
      acceptance boundaries for each of the wires.
    
      Note: zero finding is not available yet in the default version of
      Garfield.
    

    MONTE-CARLO-DRIFT

      Requests the use of the Monte Carlo drift line integration routine
      rather than the Runge-Kutta-Fehlberg integration routine.
    
      This option is particularly interesting used in conjuction with
      the more realistic variants of the DRIFT TRACK command.
    

    ISOCHRONES

      Requests calculation and plotting of isochrones. You must specify
      the interval, in microsec, after the ISOCHRONES keyword.
    
      The appearance of the isochrones is affected by:
      - the polyline and the polymarker representations ISOCHRONES,
        see the graphics !REPRESENT command for further information;
      - by a series of options which control whether the points on the
        isochrones are to be joined by lines or simply to be marked, up
        to which distance isochrone points may be joined, whether checks
        have to be made for intersects between isochrones and drift
        lines, see the &DRIFT INTEGRATION-PARAMETERS command for details.
    
      Plotting isochrones can be a CPU intensive operation, depending on
      the number of drift lines, the number of isochrones and the options
      that have been chosen.
    
      In order to plot only the isochrones and not the drift lines, one
      uses ISOCHRONES in conjunction with NOLINE-PLOT.
    
      The drift time used for the isochrones is measured from the wire
      or the solid where the electron or ion ends up. Isochrones are
      only plotted for electrons and ions that do reach a wire or a solid.
      Isochrones are not plotted for particles that reach a replica of a
      wire (in case of periodic chambers).
    
      Note that isochrones can also be obtained with two other commands:
      TABLE CONTOUR and PLOT CONTOUR TIME. The latter two commands are
      do not take the end-point of the electrons into account, and as a
      result may produce isochrones joining points leading to different
      wires or solids.
    
      [Isochrones are by default not plotted.]
    

    LINE-PLOT

      Requests plotting of the drift lines. You may wish to switch this
      option off if you want to see only isochrones.
    
      This option is initially on.
    

    LINE-PRINT

      Requests printing of drift line summary data. This option is not
      compatible with LINE-PLOT in interactive VM/CMS (because of system
      shortcomings) unless the output has been rerouted (> dsname).
    
      This option is initially off.
    

    ELECTRON

      Requests drifting of electrons.
    

    ION

      Requests drifting of ions.
    

    POSITIVE

      By default, electrons are drifted with negative charge and ions with
      positive charge. If you wish to see the origin of the electrons and
      ions arriving at a given position, you may wish to reverse the sign.
    
      The POSITIVE option forces the charge to be positive, no matter
      whether the particle is an electron or an ion.
    

    NEGATIVE

      By default, electrons are drifted with negative charge and ions with
      positive charge. If you wish to see the origin of the electrons and
      ions arriving at a given position, you may wish to reverse the sign.
    
      The NEGATIVE option forces the charge to be negative, no matter
      whether the particle is an electron or an ion.
    

    Keyword index. Formatted on 10/11/98.