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, October 16th 2024 (last respin 2024.1.2) 06-May-2024
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MATERIAL
Defines a single-element material or (coupled to a COMPOUND card) a compound
See also COMPOUND, LOW-MAT, MAT-PROP
WHAT(1) = atomic number (meaningful only when NOT coupled to a COMPOUND
card; otherwise set = 0.)
No default.
WHAT(2) = atomic weight in g/mole (meaningful only when NOT coupled to a
COMPOUND card; otherwise set = 0.)
Default: computed according to the natural composition of an
element with atomic number WHAT(1) if not coupled to a COMPOUND
card, no default otherwise.
WHAT(3) = density in g/cm**3. Note that if the density is lower than 0.01,
the material is considered to be a gas at atmospheric pressure
unless set otherwise by MAT-PROP
No default.
WHAT(4) = number (index) of the material
Default = NMAT + 1 (NMAT is the current number of defined
materials. Its value is = 25 before any MATERIAL card is given,
and doesn't change if WHAT(4) overrides a number which has
already been assigned)
WHAT(5) >= 2.0: alternate material number (or name, in name-based input)
for ionisation processes (this material will be used
instead of WHAT(1) for dE/dx etc.)
0 =< WHAT(5) =< 2: ignored
< 0.0: reset to default
Default: no alternate material
WHAT(6) = mass number of the material: set = 0 unless a specific
individual isotope is desired. If not zero a nucleus of the given
mass number is used by the EVAP generator for inelastic
collisions, else the natural isotopic composition of the WHAT(1)
element is used (but see Note 9).
For isotopic composition other than natural or single isotope,
see COMPOUND
SDUM = name of the material
No default.
Default (option MATERIAL not given): standard pre-defined
material numbers are used (see list in (5)).
Notes:
- 1) MATERIAL cards can be used in couple with COMPOUND cards in order
to define compounds, mixtures or isotopic compositions. See COMPOUND
for input instructions.
- 2) Material number 1 is always Black Hole (called also External Vacuum)
and it can not be redefined. (All particles vanish when they reach
the Black Hole, which has an infinite absorption cross section)
-
3) Material number 2 is always Vacuum (of zero absorption cross
section) and it can not be redefined.
- 4) Although the material number can be omitted, it is not recommended
to do so if the input is number-based. On the contrary, it may be
convenient to omit it in name-based inputs, but only if the material
name has not already been used, explicitely (by another MATERIAL
card) or implicitely (predefined material, see list (5)). If the
number of the material has been omitted, it is recommended to use
only its name in COMPOUND and ASSIGNMAt commands.
- 5) In an explicitely number-based input (declared as such by
WHAT(4) = 4.0 in command GLOBAL) it is allowed to redefine a
material name overriding a number already assigned (either by
default, see list (5), or by a previous MATERIAL card), or by using a
new number. But in a name-based input, whether defined as such by
default or explicitely (by WHAT(4) = 1.0 in command GLOBAL), a
material name can be redefined only by explicitly setting the
material number in WHAT(4) of the MATERIAL card, and that number
must be identical to that previously assigned.
- 6) If the number has not been assigned before, it must be the next
number available (26, 27... for successive MATERIAL cards).
In a number-based input, it is dangerous to leave empty gaps in the
number sequence, although the program takes care of redefining the
number: in fact, the incorrect number is likely to be still used in
other commands such as ASSIGNMAt and COMPOUND, leading to crashes or
to undetected errors.
If the input is name-based and the number is not given explicitely,
the program automatically assigns the next available number and the
number sequence is automatically respected. The assigned number can
be read from standard output, but the user only needs to refer to
that material by its name in other input cards.
- 7) Materials having a different density at the macroscopic and at the
microscopic level (e.g. spongy matter or approximations for not
entirely empty vacuum) need a special treatment regarding stopping
power (density effect). In such cases, see MAT-PROP.
- 8) If low-energy neutron transport is desired, the material name
must coincide with that of one of the low-energy neutron
cross section materials in the Fluka library (see (10)), or a
correspondence must be set using option LOW-MAT.
- 9) If the card concerns an element that does not exist in nature,
setting WHAT(6) = 0.0 cannot provide the natural isotopic
composition. Therefore a single isotope will be selected (usually
the one with the longest half-life). To avoid confusion, it is
suggested to declare explicitly instead the isotope desired.
- 10) The largest atomic number that can be handled by FLUKA is 100.
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
MATERIAL 1. 1.0079 8.988E-5 3. 0.0 1. HYDROGEN
LOW-MAT HYDROGEN 1. 11. 296. 0.0 0. HYDROGEN
MATERIAL 6. 12.011 2.265 6. 0.0 0. CARBON
MATERIAL 6. 12.011 2.0 26. 0.0 0. GRAPHITE
LOW-MAT CARBON 6. -3. 296. 0.0 0. GRAPHITE
MATERIAL 41. 92.9064 8.57 27. 0.0 0. NIOBIUM
MATERIAL 48. 112.411 8.650 28. 0.0 0. CADMIUM
MATERIAL 24. 51.996 7.19 29. 0.0 0. CHROMIUM
MATERIAL 27. 58.93320 8.90 30. 0.0 0. COBALT
* Several cases are illustrated:
* Hydrogen, pre-defined as material 3, is re-defined with the same number, but
* as monoisotopic 1-H. Command LOW-MAT has been added to force this material to
* be mapped to CH2-bound 1-H for what concerns low energy neutron transport.
* Carbon, pre-defined as material 6.0, is re-defined with a different density,
* and is also redefined with a different name (GRAPHITE), mapped to
* graphite-bound carbon, and is assigned a number corresponding to the first
* free slot (26.0).
* Niobium, Cadmium, Chromium and Cobalt are added to the list, and are assigned
* further consecutive numbers.
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