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5.2} Pre-defined materials

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 Materials can be easily defined by option MATERIAL by assigning a density, a
 name, a code number (compulsory only if the input has been defined as purely
 numeric), and, in the case of single elements, an atomic number and an atomic
 weight. For compounds, the MATERIAL option card must be accompanied by a
 COMPOUND definition referred to the same material name. If low-energy neutrons
 (E < 20 MeV) need to be transported, the chosen name of a single element
 material must coincide with that of one for which cross sections are available
 (see Table in 10}).

 However, for user's convenience, 25 common single-element materials are already
 pre-defined (see Table below): they are assigned a default density, name and
 code number even if no MATERIAL definition has been given. The user can
 override any of these if desired (but cannot change the code number), and can
 add more material definitions by means of one or more MATERIAL cards. The only
 constraints are:
* the number sequence of the defined materials must be UNINTERRUPTED, i.e.,
there may not be any gap in the numbering sequence from 25 onwards. If the input is name-based, omitting the material number is the easiest way to ensure this, since the code will assign a correct number automatically.
* if one of the pre-defined materials is re-defined using the same name, its
number (if expressed explicitely) must be equal to that of the pre-defined material. Note that the above constraints can be ignored if the input is name-based and the material number in the MATERIAL option is left blank. In that case, the material name must be used in all relevant command (e.g. ASSIGNMAt, COMPOUND). In addition to the 25 pre-defined single-element materials, some pre-defined compounds are available. For them, the stopping power of charged particles is not calculated directly from the component elements by the Bragg formula, but the Sternheimer parameters and the ionisation potential recommended by ICRU [ICRU84] are applied. Composition is also that recommended by ICRU. Reference to these pre-defined compounds is normally by name and no MATERIAL and COMPOUND cards are needed: if the input is explicitly number-based only (via command GLOBAL), a number needs to be assigned to them using a MATERIAL card, of course leaving no gaps in the numbering sequence. If a user defines a compound with the same name and similar composition, the code automatically "matches" its stopping power parameters to those of the pre-defined one. It is also possible to modify the Sternheimer parameters with command STERNHEIme and the ionisation potential with MAT-PROP. List of pre-defined single-element FLUKA materials -------------------------------------------------- Fluka name Fluka Common name A Z Density number [g/cm^3] BLCKHOLE 1 Blackhole or External Vacuum 0 0 0 VACUUM 2 Vacuum or Internal Vacuum 0 0 0 HYDROGEN 3 Hydrogen 1.00794 1. 0.0000837 HELIUM 4 Helium 4.002602 2. 0.000166 BERYLLIU 5 Beryllium 9.012182 4. 1.848 CARBON 6 Carbon 12.0107 6. 2.000 NITROGEN 7 Nitrogen 14.0067 7. 0.00117 OXYGEN 8 Oxygen 15.9994 8. 0.00133 MAGNESIU 9 Magnesium 24.3050 12. 1.740 ALUMINUM 10 Aluminium 26.981538 13. 2.699 IRON 11 Iron 55.845 26. 7.874 COPPER 12 Copper 63.546 29. 8.960 SILVER 13 Silver 107.8682 47. 10.500 SILICON 14 Silicon 28.0855 14. 2.329 GOLD 15 Gold 196.96655 79. 19.320 MERCURY 16 Mercury 200.59 80. 13.546 LEAD 17 Lead 207.2 82. 11.350 TANTALUM 18 Tantalum 180.9479 73. 16.654 SODIUM 19 Sodium 22.989770 11. 0.971 ARGON 20 Argon 39.948 18. 0.00166 CALCIUM 21 Calcium 40.078 20. 1.550 TIN 22 Tin 118.710 50. 7.310 TUNGSTEN 23 Tungsten 183.84 74. 19.300 TITANIUM 24 Titanium 47.867 22. 4.540 NICKEL 25 Nickel 58.6934 28. 8.902 List of pre-defined ICRU compounds ---------------------------------- Fluka name Common name Density [g/cm^3] WATER Water 1.0 POLYSTYR Polystyrene 1.06 PLASCINT Plastic scintillator 1.032 PMMA Polymethyl methacrylate, Plexiglas, Lucite, Perspex 1.19 BONECOMP Compact bone 1.85 BONECORT Cortical bone 1.85 MUSCLESK Skeletal muscle 1.04 MUSCLEST Striated muscle 1.04 ADTISSUE Adipose tissue 0.92 KAPTON Kapton polyimide film 1.42 POLYETHY Polyethylene 0.94 AIR Dry air at NTP conditions 0.00120479 5.3 Physical units ------------------ Physical units consistently used in FLUKA input and output are: distance cm (and derived units cm2, cm3 for areas and volumes) energy GeV Exceptions: eV is used for average ionisation potential and for damage energy threshold input by option MAT-PROP g/(MeV cm2) is used for the first Birks coefficient input by option TCQUENCH, and g2/(MeV2 cm4) for the second coefficient. momentum GeV/c temperature degree Kelvin solid angle sr (exception: degrees may be used, on user's request, with option USRYIELD) magnetic field T electric field kV/cm time s (option TCQUENCH) or ns (option TIME-CUT) activity Bq LET keV/(micrometer g/cm3) dose equivalent pSv

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