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FLUKA: 8.1} GEOBEGIN card Previous Index Next

8.1} GEOBEGIN card


 This card follows the general FLUKA format (see description in 6}).
 It can be in free format if the latter has been requested with
 option FREE. The rest of the geometry must be in a special fixed
 format described below, unless free geometry format has been requested
 by a GLOBAL command at the beginning of input.

 The meanings of the WHAT and 
SDUM
parameters are:
WHAT(1)
: not used
WHAT(2)
: absolute accuracy parameter (Aa) in units of 10**-6 cm. It is used for tracking and boundary identification. Aa should be larger than Ar*L , where L is the largest coordinate value in the geometry description (excluding the outer blackhole shell containing it and Ar is the relative accuracy achievable in double precision (of the order of 1.E-14 - 1.E-15).
Default
= 0.0001
WHAT(3)
> 0.0 : logical unit for geometry input. The name of the corresponding file must be input on the next card if
WHAT(3)
is different from 5. Note that values of
WHAT(3)
/= 5.0 and < 21.0 must be avoided because of possible conflicts with FLUKA pre-defined units.
Default
= 5.0 (i.e. geometry input follows)
WHAT(4)
> 0.0 : logical unit for geometry output. If different from 11, the name of the corresponding file must be input on the next card if
WHAT(3)
= 0 or 5, otherwise on the card following the next one. Values of
WHAT(4)
/= 11.0 and < 21.0 must be avoided because of possible conflicts with FLUKA pre-defined units.
Default
= 11.0 (i.e. geometry output is printed on the standard output)
WHAT(5)
: parentheses optimisation level = i0 + i1 x 1000 i0 = 1: logical optimisation only activated 2: logical + "plane" optimisation activated 3: logical + "plane" + "bounding box" optimisation activated (
Default
: 3) i1 > 0 forces optimisation even if no parentheses are found in the region under scrutiny (
Default
: 0) * Start_Devel_seq
WHAT(6)
: if > 0 it indicates the number of geometry output lines to be skipped before starting writing debugging lines. Please note that the output can rapidly become huge * End_Devel_seq * Start_Prod_seq *
WHAT(6)
: not used * End_Prod_seq
SDUM
= COMBINAT : Combinatorial geometry is used. See section on Combinatorial Geometry for input description Other geometries, available in older versions of FLUKA, are no longer supported.
Default
: COMBINAT
SDUM
= COMBNAME : Combinatorial geometry is used in free format, and names can be used instead of body and region numbers
Default
(option GEOBEGIN not given): not allowed! GEOBEGIN and GEOEND must always be present.

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