---------------------------- Transport of charged particles can be done in many ways: without delta ray production and ionisation fluctuations (continuous slowing down approximation), with ionisation fluctuations and no delta rays, with delta ray production above a chosen energy threshold and no ionisation fluctuations below the threshold, and with both: delta rays above the threshold and ionisation fluctuations below it. Depending on the application type chosen with option DEFAULTS, different defaults and thresholds apply, which can be modified by the user by means of options IONFLUCT, DELTARAY and EMFCUT. Option IONFLUCT is used to request (restricted) ionisation fluctuations on a material basis. In FLUKA, these fluctuations are not simulated according to Landau or Vavilov theory but according to an original statistical approach [Fas97a]. They can be requested separately for electrons and positrons and for muons and charged hadrons. Delta ray production thresholds are instead set for the two particle families by two separate options, which have already been mentioned above in the context of production cutoffs: EMFCUT and DELTARAY. DELTARAY can be used also to define (and print) the mesh width of the stopping power tabulations used by the program. The user has also the possibility to change the default parameters used in the calculation of stopping power. Command STERNHEIme allows to change the density effect parameters,and MAT-PROP can set, in addition to several other material properties, a user-defined average ionisation potential.
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