Material and media definition in HGEANT

  • Each medium is characterized by a name.
  • The names of the materials and the media are identical. *For each medium all parameters needed by the GEANT routines GSMATE, GSMIXT, GSTMED and GSCKOV are defined.

ALERT! The predefined materials in GEANT are not used!

The following parameters are needed:
Parameter Description
int ncomp number of components in the material (ncomp= 1 for a basic material and <1 or >1 for a mixture ; see NLMAT in Geant 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 radleng radiation length RADL (only for a basic material) or
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.

  • Examples:

The variable npckov is 0 for all optically inactive media except some special media used in the RICH to track the Cerenkov photons.
These media have additional parameter arrays:
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

The following parameters used in the GEANT tracking routines are normally not read. The default values are -1 and the real values are automatically calculated by GEANT.
But 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 at the end of the normal medium definition:
float madfld maximum angular deviation TMAXFD due to the 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 //.

-- IlseKoenig - 16 Jul 2007
Topic revision: r1 - 2007-07-16, IlseKoenig
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