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1.2} Geometry

  -------------

  A part of the code where efficiency, accuracy, consistency and flexibility
  have combined giving very effective results is the FLUKA geometry. Derived
  from the Combinatorial Geometry package, it has been entirely rewritten. A
  completely new, fast tracking strategy has been developed, with special
  attention to charged particle transport, especially in magnetic fields. New
  bodies have been introduced, resulting in increased rounding accuracy, speed
  and even easier input preparation.

  * Combinatorial Geometry (CG) from MORSE [Emm75], with additional bodies
    (infinite circular and elliptical cylinder parallel to X,Y,Z axis, generic
    plane, planes perpendicular to the axes, generic quadrics).
  * Possibility to use body and region names instead of numbers.
  * Possibility of using body combinations inside nested parentheses.
  * Geometry directives for body expansions and roto-translation
    transformations.
  * Distance to nearest boundary taken into account for improved performance.
  * Accurate treatment of boundary crossing with multiple scattering and
    magnetic or electric fields.
  * The maximum number of regions (without recompiling the code) is 10000.
  * The tracking strategy has been substantially changed with respect to the
    original CG package. Speed has been improved and interplay with charged
    particle transport (multiple scattering, magnetic and electric field
    transport) has been properly set.
  * A limited repetition capability (lattice capability) is available. This
    allows to avoid describing repetitive structures in all details. Only one
    single module has to be described and then can be repeated as many times
    as needed. This repetition does not occur at input stage but is hard-wired
    into the geometry package, namely repeated regions are not set up in
    memory, but the given symmetry is exploited at tracking time using the
    minimum amount of bodies/regions required. This allows in principle to
    describe geometries with even tens of thousands regions (e.g. spaghetti
    calorimeters) with a reasonable number of region and body definitions.
  * Voxel geometry is available on option, completely integrated into CG.

  Special options:
  * Geometry debugger.
  * Plotting of selected sections of the geometry, based on the Ispra PLOTGEOM
    program.
  * Pseudoparticle RAY to scan the geometry in a given direction.


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