defines a compound, alloy or mixture, made of several materials, or even a
mixture of different isotopes
See also ASSIGNMAt, CORRFACT, LOW-MAT, MATERIAL, MAT-PROP
If WHAT(1) > 0.0 and WHAT(2) > 0.0 :
WHAT(1) = atom relative content of first material in the compound
WHAT(2) = index of first material
If WHAT(1) < 0.0 and WHAT(2) > 0.0 :
|WHAT(1)| = mass fraction of first material in the compound
WHAT(2) = index of first material
If WHAT(1) < 0.0 and WHAT(2) < 0.0 :
|WHAT(1)| = volume fraction of first material in the compound
|WHAT(2)| = index of first material
No default
In a similar way, WHAT(3) and WHAT(4) refer to the second material in the
compound, WHAT(5) and WHAT(6) to the third one.
SDUM = name of the compound
Default (option COMPOUND not requested): no compound is defined
For more than three materials in the same compound, add as many COMPOUND
cards with the same SDUM name as needed (but the maximum number of
components per compound is 80, and the maximum total number of components
is 1000).
Notes:
1) Option COMPOUND must always be used in conjunction with a MATERIAL
card having the same SDUM name (see MATERIAL). MATERIAL cards used
for this purpose provide the density of the compound, its material
number and name (WHAT(1) and WHAT(2) of the MATERIAL option, namely
atomic and mass number, are ignored).
2) The order of MATERIAL and COMPOUND cards is irrelevant.
3) The atom (or molecule) content, mass fraction or volume fraction
need only to be given on a relative basis (normalisation is done
automatically by the program).
4) Partial pressures of an (ideal) gas are equivalent to molecule
fractions and also to volume fractions.
5) If a compound is defined by volume fractions of the components
(either elements or compounds themselves - see Note 8 below for
recursive definitions), FLUKA internally calculates the atomic
densities of each component using the densities indicated in the
respective MATERIAL cards: in this case, therefore, (and only in
this case), it is important that these correspond to the actual
densities.
6) Isotopic compositions other than natural can be defined by the
COMPOUND option too.
7) When using the LOW-NEUT option (explicitly or by default set by the
DEFAULTS option), a special data set containing low-energy neutron
cross-sections for each material used must be available. The data
sets are combined in a single file, delivered with the FLUKA program
(logical input unit 9, see 3}). Each low-energy neutron data set is
identified either by name (if equal to a FLUKA name and unique or
first with that name), or/and by one or more identifiers given with
a card LOW-MAT when necessary to remove ambiguity.
In the case of a composite material defined by a COMPOUND option,
two possibilities are allowed (see LOW-MAT):
a) to associate the FLUKA material with a pre-mixed neutron data
set. In this case interactions take place with individual nuclei
at high energy, while average cross-sections are used for
low-energy neutrons. Note that no pre-mixed neutron data set is
yet available (at the moment the standard sets contain pure
elements only).
b) to associate the FLUKA material with several elemental neutron
data sets (one per component element). In this case both
high-energy and low-energy neutron interactions take place with
individual nuclei. This is the only possibility at present but
it may change in the future.
8) Recursion is allowed, i.e. the components of a composite material
can be composite materials. The depth of recursion is only limited
by the size of the internal arrays (in case of overflow a message
is issued and the job is terminated). Different levels of recursion
can use different units in the definition of the component fractions
(atoms, mass or volume fractions). Note, however, that if a compound
is put together from different composite molecules, the atomic and
molecular fractions have to be given without normalisation (use the
chemical formulae directly).
What follows is an example for a simple compound BOOZE containing
50 weight percent of water and 50 of ethanol.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
MATERIAL 1.0 1.0 .0000899 3.0 0.0 0.0 HYDROGEN
MATERIAL 6.0 12.0 2.0 4.0 0.0 0.0 CARBON
MATERIAL 8.0 16.0 0.00143 5.0 0.0 0.0 OXYGEN
MATERIAL 0.0 0.0 1.0 20.0 0.0 0.0 WATER
MATERIAL 0.0 0.0 0.7907 7.0 0.0 0.0 ETHANOL
MATERIAL 0.0 0.0 0.9155 8.0 0.0 0.0 BOOZE
COMPOUND 2.0 3.0 1.0 5.0 0.0 0.0 WATER
COMPOUND 2.0 4.0 6.0 3.0 1.0 5.0 ETHANOL
COMPOUND -50.0 20.0 -50.0 7.0 0.0 0.0 BOOZE
* Note that in the above example materials 4, 5, 7 and 8 have been defined
* overriding the default FLUKA material numbers.
Example of how COMPOUND is commonly used to define a mixture (concrete):
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
* definition of material 27 (concrete) as compound: H (1%), C(0.1%),
* O(52.9107%), Na(1.6%), Mg(0.2%), Al(3.3872%), Si(33.7021%), K(1.3%),
* Ca(4.4%), Fe(1.4%)
MATERIAL 19.0 39.0983 0.862 26.0 0.0 0.0 POTASSIU
MATERIAL 0.0 0.0 2.35 27.0 0.0 0. CONCRETE
COMPOUND -0.01 3.0 -0.001 6.0 -0.529107 8. CONCRETE
COMPOUND -0.016 19.0 -0.002 9.0 -0.033872 10. CONCRETE
COMPOUND -0.337021 14.0 -0.013 26.0 -0.044 21. CONCRETE
COMPOUND -0.014 11.0
* In the above example, elements 3 (hydrogen), 6 (carbon), 8 (oxygen),
* 9 (magnesium), 10 (aluminium), 11 (iron), 14 (silicon), 19 (sodium) and
* 21 (calcium) are not defined because the corresponding pre-defined FLUKA
* materials are used (see 5}). Potassium is not pre-defined, therefore it is
* assigned a new numbers 26 (that keeps the numbering sequence continuous,
* since the last FLUKA pre-defined material has number 25). The name is
* chosen to correspond with the potassium neutron cross section data set.
* (Chap. 10})
More complex uses of COMPOUND in connection with MATERIAL and LOW-MAT are
illustrated by examples in 15}.
