Media file

Each medium is characterized by a name. The names of the materials and the media are identical. Together with the name all parameters must be given which are needed for the Geant routines GSMATE, GSMIXT, GSTMED and GSCKOV.
There are no predefined materials!

The following parameters are needed:

  • int ncomp - number of components in the material (ncomp= 1 for a basic material and <1 or >1 for a mixture
    If ncomp > 0 the array wm contains the proportion by weight of each material in the mixture.
    If ncomp < 0 the array wm contains the proportion by number of atoms of each kind.
    For more detailed information see NLMAT in Geant3 routine GSMIXT
  • float aw[ncomp] - atomic weights A for the components
  • float an[ncomp] - atomic numbers Z for the components
  • float dens - density DENS in g cm(**-3)
  • float wm[ncomp] - weights WMAT of each component in a mixture (only for a mixture)
  • int sensflag - sensitivity flag ISVOL
  • int fldflag - fieldflag IFIELD
  • float fld - maximum field value FIELDM in kilogauss
  • float epsil - boundary crossing precision EPSIL
  • int npckov - number of values used to define the optical properties of the medium.
    The variable npckov is 0 for all media except some special media used for the Rich where the tracking of the Cerenkov photons is necessary. These media have additinal parameters
    • float ppckov[npckov] - photon momentum in eV
    • float absco[npckov] - absorption length in case of dielectric and of absorption probabilities in case of a metal
    • float effic[npckov] - detection efficiency
    • float rindex[npckov] - refraction index for a dielectric, rindex[0]=0 for a metal
      Remark: In the present program version a mixture may contain a maximum of 5 components. If this is not sufficient one has to change MAXCOMP in hgeomedium.h.

The following parameters are normally not read. The default values are -1 and the real values are automatically calculated by Geant. If you want to set these values by yourself, you must type the keyword AUTONULL in your media file. After this keyword all media must contain these additional 4 parameters before the Cerenkov (int npckov).

  • float madfld - maximum angular deviation TMAXFD due to field
  • float maxstep - maximum step permitted STEMAX
  • float maxde - maximum fractional energy loss DEEMAX
  • float minstep - minimum value for step STMIN

Comments can be placed before a medium in a new line starting with //

Example for a basic material

ALUMINIUM 1 26.98 13 2.7
0 0 0 0.0001
0
corresponds to :
name ncomp aw an dens
sensflag fldflag fld epsil
npckov


Example for a mixture where the content of each material in the mixture is given as proportion by weight

air 3 14.01 16. 39.95. 7. 8. 18. 1.205e-3 .755 .231 .014
0 1 3. .001
0
corresponds to:
name ncomp aw(1) aw(2) aw(3) an(1) an(2) an(3) dens wm(1) wm(2) wm(3)
sensflag fldflag fld epsil
npckov


Example for a mixture where the content of each material in the mixture is given as number of atoms of each kind

C4F10 -2 12.01 19. 6. 9. 7.35485e-3 4. 10.
0 1 3. .001
0
corresponds to:
name ncomp aw(1) aw(2) an(1) an(2) dens wm(1) wm(2)
sensflag fldflag fld epsil
npckov

AUTONULL

RICHPad -2 12.01 1.00797 6. 1. 0.717e-3 1 4
1 1 3. .001
20 0.5 0.001 .00001
3
5.636 40000 1.0 1.0
7.750 2280 1.0 1.0
9.540 0.0 1.0 1.0
corresponds to
name ncomp aw(1) aw(2) an(1) an(2) dens wm(1) wm(2)
sensflag fldflag fld epsil
madlfd maxstep maxde minstep
npckov
ppckov[0] absco[0] effic[0] rindex[0]
ppckov[1] absco[1] effic[1] rindex[1]
ppckov[2] absco[2] effic[2] rindex[2]