FLUKA: MATERIAL
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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)
= NOT to be filled.
It allows to overwrite the default value of atomic weight
(in g/mole).
Default
: computed according to the natural composition of an
element with atomic number WHAT(1)
or to the identity of its
isotope specified by WHAT(6)
.
Meaningless if coupled to a COMPOUND card.
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
NOT to be filled in case of name-based input.
Default
= NMAT + 1, where NMAT is the current higher number
of defined materials. The number sequence of the defined
materials must be uninterrupted. 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
Only integer values (still in real format) make sense.
Default
= 0 i.e. natural isotopic composition of the WHAT(1)
element (but see Note 8).
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) In name-based inputs it is recommended to omit the number of the
material (and use its name in COMPOUND and ASSIGNMAt commands).
On the contrary, if the input is number-based, it is not recommended
to omit it.
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 overriding a number already assigned (either by
default, see list 5}, or by a previous MATERIAL card), or by using a
new number.
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 it 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.
6) 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.
7) 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.
8) 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.
9) The largest atomic number that can be handled by FLUKA is 100.
Example:
MATERIAL 1. 8.988E-5 0.0 1. HYDROGEN
LOW-MAT HYDROGEN 1. 11. 296. 0.0 0. HYDROGEN
MATERIAL 6. 2.265 0.0 0. CARBON
MATERIAL 6. 2.0 0.0 0. GRAPHITE
LOW-MAT CARBON 6. -3. 296. 0.0 0. GRAPHITE
MATERIAL 41. 8.57 0.0 0. NIOBIUM
MATERIAL 48. 8.650 0.0 0. CADMIUM
MATERIAL 24. 7.19 0.0 0. CHROMIUM
MATERIAL 27. 8.90 0.0 0. COBALT
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