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5 Particle and material codes

5.1 Particles codes

Each particle which can be transported by FLUKA is identified by an alphanumeric name and by an integer number. Negative values of such numerical identifiers are reserved to light and heavy ions, and to optical photons. The value 0 indicates a pseudoparticle RAY, which can be used to scan the geometry. Numbers > 200 designate "families" of particles, grouped according to some common characteristics (all hadrons, or all charged particles, etc.). In FLUKA, they are called Generalised Particles and can be used only for scoring. Various forms of scored energy, transferred momentum, induced activity etc. are also treated as Generalised Particles.

The identifier values are reported in the following Table, together with the corresponding particle numbering scheme of the Particle Data Group [PDG].

 Fluka name     Fluka number    Common name      Standard

 PDG number
                                                 (Particle Data Group)

 4-HELIUM (1)       -6          Alpha                   ---
 3-HELIUM (1)       -5          Helium-3
 TRITON   (1)       -4          Triton                  ---
 DEUTERON (1)       -3          Deuteron                ---
 HEAVYION (1)       -2          Generic heavy ion (see command HI-PROPE)
 OPTIPHOT           -1          Optical Photon          ---
 RAY (2)             0          Pseudoparticle          ---
 PROTON              1          Proton                  2212
 APROTON             2          Antiproton             -2212
 ELECTRON            3          Electron                  11
 POSITRON            4          Positron                 -11
 NEUTRIE             5          Electron Neutrino         12
 ANEUTRIE            6          Electron Antineutrino    -12
 PHOTON              7          Photon                    22
 NEUTRON             8          Neutron                 2112
 ANEUTRON            9          Antineutron            -2112
 MUON+              10          Positive Muon            -13
 MUON-              11          Negative Muon             13
 KAONLONG           12          Kaon-zero long           130
 PION+              13          Positive Pion            211
 PION-              14          Negative Pion           -211
 KAON+              15          Positive Kaon            321
 KAON-              16          Negative Kaon           -321
 LAMBDA             17          Lambda                  3122
 ALAMBDA            18          Antilambda             -3122
 KAONSHRT           19          Kaon zero short          310
 SIGMA-             20          Negative Sigma          3112
 SIGMA+             21          Positive Sigma          3222
 SIGMAZER           22          Sigma-zero              3212
 PIZERO             23          Pion-zero                111
 KAONZERO           24          Kaon-zero                311
 AKAONZER           25          Antikaon-zero           -311
 Reserved           26               ---                 ---
 NEUTRIM            27          Muon neutrino             14
 ANEUTRIM           28          Muon antineutrino        -14
 Blank              29               ---                 ---
 Reserved           30               ---                 ---
 ASIGMA-            31          Antisigma-minus        -3222
 ASIGMAZE           32          Antisigma-zero         -3212
 ASIGMA+            33          Antisigma-plus         -3112
 XSIZERO            34          Xi-zero                 3322
 AXSIZERO           35          Antixi-zero            -3322
 XSI-               36          Negative Xi             3312
 AXSI+              37          Positive Xi            -3312
 OMEGA-             38          Omega-minus             3334
 AOMEGA+            39          Antiomega              -3334
 Reserved           40               ---                 ---
 TAU+               41          Positive Tau             -15
 TAU-               42          Negative Tau              15
 NEUTRIT            43          Tau neutrino              16
 ANEUTRIT           44          Tau antineutrino         -16
 D+                 45          D-plus                   411
 D-                 46          D-minus                 -411
 D0                 47          D-zero                   421
 D0BAR              48          AntiD-zero              -421
 DS+                49          D_s-plus                 431
 DS-                50          D_s-minus               -431
 LAMBDAC+           51          Lambda_c-plus           4122
 XSIC+              52          Xi_c-plus               4232
 XSIC0              53          Xi_c-zero               4112
 XSIPC+             54          Xi'_c-plus              4322
 XSIPC0             55          Xi'_c-zero              4312
 OMEGAC0            56          Omega_c-zero            4332
 ALAMBDC-           57          Antilambda_c-minus     -4122
 AXSIC-             58          AntiXi_c-minus         -4232
 AXSIC0             59          AntiXi_c-zero          -4132
 AXSIPC-            60          AntiXi'_c-minus        -4322
 AXSIPC0            61          AntiXi'_c-zero         -4312
 AOMEGAC0           62          AntiOmega_c-zero       -4332
 Reserved           63               ---                 ---
 Reserved           64               ---                 ---

 (1) Heavy fragments produced in evaporation are loaded in a special stack
     (COMMON FHEAVY, contained in the INCLUDE file with the same name).
     The internal code for heavy evaporation fragments is the following:
     3 = deuteron, 4 = 3-H, 5 = 3-He, 6 = 4-He, 7-12 = fission fragments.
     Transport capabilities (dE/dx, with account of effective charge and
     effective charge straggling, multiple Coulomb scattering, no interaction
     yet) are now available for d, t, 3-He and 4-He.  Heavier ions can be
     transported on demand (see option IONTRANS), with or without nuclear
     interactions. Fission fragments and fragments from Fermi break-up, when
     produced, are also put in COMMON FHEAVY with id's ranging from 7 to 12
     (usually 7 and 8 for two fragments).

 (2) A "RAY" is not a real particle, but a straight line trajectory through the
     FLUKA geometry. When a primary particle (defined by options BEAM and
     BEAMPOS, or by a SOURCE subroutine) is found to be a RAY, the program
     tracks through the geometry in the given direction calculating a number of
     quantities (distance traversed in each material, number of radiation
     lengths, number of interaction lengths etc.). See (14) for instructions
     about its use.

Generalised particles (to be used only for scoring):

  ---               40          Low-energy neutrons (used only in some input
 ALL-PART          201          All transportable particles
 ALL-CHAR          202          All charged particles
 ALL-NEUT          203          All neutral particles
 ALL-NEGA          204          All negative particles
 ALL-POSI          205          All positive particles
 NUCLEONS          206          Protons and neutrons
 NUC&PI+-          207          Protons, neutrons and charged pions
 ENERGY            208          For dose scoring: Deposited energy
                                For energy fluence scoring: Kinetic energy
 PIONS+-           209          Charged pions
 BEAMPART          210          Primary (source or beam) particles
 EM-ENRGY          211          Electromagnetic energy (of electrons, positrons
                                or photons)
 MUONS             212          Muons
 E+&E-             213          Electrons and positrons
 AP&AN             214          Antiprotons and antineutrons
 KAONS             215          All kaons
 STRANGE           216          All kaons and all hyperons and anti-hyperons
                                (i.e., all strange particles)
 KAONS+-           217          Charged kaons
 HAD-CHAR          218          Charged hadrons
 FISSIONS          219          Fissions
 HE-FISS           220          High energy fissions
 LE-FISS           221          Low energy fissions
 NEU-BALA          222          Neutron balance (algebraic sum of outgoing
                                neutrons minus incoming neutrons for all
 HAD-NEUT          223          Neutral hadrons
 KAONS0            224          Neutral kaons
 C-MESONS          225          Charmed mesons
 C-(A)BAR          226          Charmed (anti)baryons
 CHARMED           227          Charmed hadrons
 DOSE              228          Dose (energy deposited per unit mass, GeV/g)
 UNB-ENER          229          Unbiased deposited energy (GeV) (3)
 UNB-EMEN          230          Unbiased electromagnetic energy (of electrons,
                                positrons or photons) (GeV) (3)
 X-MOMENT          231          X component of momentum transfer (GeV/c)
 Y-MOMENT          232          Y component of momentum transfer (GeV/c)
 Z-MOMENT          233          Z component of momentum transfer (GeV/c)
 ACTIVITY          234          Activity per unit volume (Bq/cm3) (4)
 ACTOMASS          235          Activity per unit mass (Bq/g)  (4)
 SI1MEVNE          236          Silicon 1 MeV-equivalent flux (cm-2)
 HADGT20M          237          Hadrons with energy > 20 MeV (cm-2)
 NIEL-DEP          238          Non Ionising Energy Loss deposition (GeV) (5)
 DPA-SCO           239          Displacements per atoms
 DOSE-EQ           240          Dose Equivalent (pSv) (6)
 DOSE-EM           241          Dose Electromagnetic only (GeV/g)
 NET-CHRG          242          Net charge
 DOSEQLET          243          Dose equivalent with Q(LET) (pSv) (7)
 RES-NIEL          244          Restricted above damage threshold NIEL (GeV) (5)

 (3) "Unbiased energy" means that the energy deposited (or the energy fluence)
     is scored with weight 1, independent of the actual weight of the particle.
     Of course, the result will have no physical meaning, but in some
     circumstances it will provide useful information about the run itself (for
     instance in order to optimise biasing).

 (4) "Activity per unit volume" and "Activity per unit mass"
     are meaningful only when used within a 2D or 3D USRBIN estimator
     associated (by means of the DCYSCORE option) with a decay time defined
     with the DCYTIMES option. The resulting output units are Bq/cm**3 and
     Bq/g respectively, unless a binning by region or a special binning is
     requested, in which case the output is Bq or Bq cm**3/g.

 (5) "Non Ionizing Energy Loss deposition" describes the energy loss
     due to atomic displacement (recoil nucleus) as a particle traverses a
     material. The "Restricted NIEL" gives the same energy loss but restricted
     to recoils having an energy above the damage threshold defined for each
     material with the use of MAT-PROP with SDUM=DPA-ENER.

 (6) "Dose equivalent" is computed using various sets of conversion
     coefficients (see AUXSCORE for details) converting particle fluences
     into Ambient Dose equivalent or Effective Dose. Dose Equivalent of particles
     for which conversion coefficients are not available, tipically heavy ions,
     can be calculated by scoring generalised particle DOSEQLET.

 (7) "Dose equivalent" is computed using the Q(LET) relation as
     defined in

 ICRP60 [ICRP60], where LET is LET_oo in water

5.2 Pre-defined materials

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

 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

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