ELCFIELD

    defines an homogenous electric field

    See also MGNFIELD

     
WHAT(1)
 = largest angle (in degrees) that a particle is allowed to travel
               in a single step
               
Default
: 20 degrees

     
WHAT(2)
 = error of the boundary iteration (minimum accuracy accepted in
               determining a boundary intersection)
               
Default
: 0.01 cm

     
WHAT(3)
 = minimum step if the step is forced to be smaller due to a too
               large angle
               
Default
: 0.1 cm
     
WHAT(4)
 = Ex (x-component of the electric field, in MV/m)

     
WHAT(5)
 = Ey (y-component of the electric field, in MV/m)

     
WHAT(6)
 = Ez (z-component of the electric field, in MV/m)

               
Default
 (Ex = Ey = Ez = 0.0): user-supplied subroutine
               ELEFLD is assumed to provide the actual values
               (see Notes 2 and 3 below)

     
SDUM
 :    not used
     
Notes:
         1) If Ex = Ey = Ez = 0, the user-written subroutine ELEFLD is
            called at each step to get the direction cosines and the
            module (in MV/m) of the electric field as a function of
            region or of coordinates or time. A sample subroutine is 
            provided with the FLUKA code; instructions on how to write
            user-supplied routines can be found in 13}.

         2) Note that the argument list of subroutine ELEFLD is
            ( X, Y, Z, T, ETX, ETY, ETZ, E, NREG, IDISC )
            where ETX, ETY, ETZ are the DIRECTION COSINES of the electric
            field at point X, Y, Z, at time T (NOT the components of the
            field! The field magnitude is given by E). For this reason, it
            is imperative that ELEFLD returns normalised values of ETX,
            ETY and ETZ such that the sum of their squares is = 1.0
            IN DOUBLE PRECISION.
            Three zero values are not accepted: if the field is zero
            at the point in question, you must return for instance 0, 0, 1
            and E = 0. On the contrary, note that Ex, Ey, Ez in the
            ELCFIELD option, given by 
WHAT(4)
...
WHAT(6)
 as described
            above, are the field components and not the cosines.

         3) Electric field tracking is performed only in regions defined
            as electric field regions by command ASSIGNMAt. It is
            strongly recommended to define as such only regions where an
            electric field effectively exists, due to the complexity
            of the tracking algorithm used in electric/magnetic fields.
            To define a region as having an electric field and to return
            systematically E = 0 in that region via subroutine ELEFLD, is
            not allowed.

         4) Tracking in electric fields is possible at present only in
            vacuum regions. Arbitrary combinations of electric and magnetic
            fields are supported. Whenever an electric field is present
            the tracking is performed with a Runge-Kutta-Gill 4th order
            algorithm for the combined electric and magnetic (if any) fields.
            The same approach can be requested also for dis-homogeneous
            magnetic fields (in vacuum) even if no electric field is
            present, using 
SDUM
=RUNGKUTT in the MGNFIELD card

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