starts the geometry description
(see also GEOEND, PLOTGEOM)
WHAT(1) <> 0.0 : tracking errors are not printed
Default = 0.0 (geometry errors are printed)
WHAT(2) : used to set the accuracy parameter - reserved
for program development
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(3) /= 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)
WHAT(6) : not used
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.
Note: Geometry input and output:
i) If WHAT(3) and WHAT(4) are both =< 0, the geometry input and
output are part of the standard I/O streams: the GEOBEGIN
card must be immediately followed by the Combinatorial
Geometry input, and then by GEOEND. (See Example 1 below).
ii) If WHAT(3) is > 0 (and not = 5) and WHAT(4) is =< 0, GEOBEGIN
must be followed by one card with the name of the CG input
file, and then by GEOEND. (See Example 2 below).
iii) If WHAT(4) is > 0 (and not = 11) and WHAT(3) is =< 0, GEOBEGIN
must be followed by one card with the name of the CG output
file, then by the CG input, and then by GEOEND. (See Example 3 below).
iv) Otherwise, if WHAT(3) is > 0 (and not = 5), and WHAT(4) is > 0
(and not = 11), GEOBEGIN must be followed, in the order, by
a line with the name of the CG input file, another line with
the name of the CG output file and the GEOEND card.
(See Example 4 below).
The CG output is essentially an echo of the input, and gives
in addition some information on storage allocation of body and
region data. It is recommended to check on it that the
geometry description has been correctly reproduced, since
column alignment errors are critical due to the CG strict
input format. In case of severe error (next region not found,
or similar) the CG output will also contain all error and
debugging messages. Minor tracking problems, however, are
reported on the error message file (logical unit 15, see 3}),
unless reporting has been de-activated by setting WHAT(1)<>0.
Special algorithms have been implemented in the Combinatorial
Geometry package of FLUKA in order to minimise tracking errors
due to rounding, to improve tracking speed and to handle
charged particle transport near boundaries and in magnetic
fields. Since these facilities could not be made readily
available in other geometries previously used in FLUKA, the
latter have been removed from the code. Combinatorial Geometry
is thus the only geometrical package available at present.
Information on how to set up Combinatorial Geometry input is
given in 8}
End of geometry information must end with a GEOEND card (see).
The same card can also be used to activate a geometry debugger.
Option PLOTGEOM allows to draw sections of the geometry on
planes specified by the user.
Only one GEOBEGIN card is allowed.
Example 1:
* CG Input follows, output is printed as part om Main Output
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
GEOBEGIN 0. 0. 0. 0. 0. 0.COMBINAT
Example 2:
* CG Input read from file BigHall.geo, output printed as part om Main Output
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
GEOBEGIN 0. 0. 25. 0. 0. 0.COMBINAT
BigHall.geo
Example 3:
* CG Input follows, output is printed on file geo2.out
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
GEOBEGIN 0. 0. 0. 26. 0. 0.COMBINAT
geo2.out
Example 4:
* CG Input read from file BigHall.geo,, output printed on file geo2.out
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
GEOBEGIN 0. 0. 25. 26. 0. 0.COMBINAT
BigHall.geo
geo2.out
