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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.