GEANT geometry by TZ titles

CMSIM offers a standard way of building sub-detector GEANT geometry from TZ titles. This is performed by the routines DCGEAN and DCGEOM which interpret the title blocks GEAN and GEOM respectively and make appropriate actions requested by these titles.

The title block for GEAN has the following structure:

 
*DO  GEAN  <idn>   -A4CW -c1/80     #. title header line
 :SDET          #. Subdetector keyword name (e.g. TRAK)
   ...
  followed by blocks of data with a 4-character keyword and values
   ...

The numeric identifier <idn> contains packed information with the level of description (in the least significant digit) and the alternate version number if any (in the higher digit). Zero in the least significant digit specifies that the title is valid for all levels of description (simple, average or detailed). The title block is selected if the requested action in GEOM data card for the sub-detector keyword SDET matches with the numeric identifier of the block.

The following keywords can be used:

The constants which follow each keyword are the same as the call parameters required by the respective GEANT routine with the exception that the material and media are defined by a character sequence instead of a number.

The parameters which follow each keyword are defined as follows:

• CALL - a key word indicating the routine to be invoked (e.g., TRAK, PBXL, TGBX, TGFX, TSBX, TSFX, ECAL, ECBX, ECFX)
• CKOV
  • material name
  • number of bins in the table NPCKOV
  • photon momenta (PPCKOV), absorbtion coefficients (ABSCO), detection efficiencies (EFFIC) and refractive indices (RINDEX)
• DVN /DVN2/DVT /DVT2/DVX
  • volume name (character string)
  • name of the mother (character string)
  • followed by division related parameters:
    • NDIV, IAXIS (GSDVN)
    • NDIV, IAXIS, C0, Material name (GSDVN2)
    • STEP, IAXIS, material name, NDVMX (GSDVT)
    • STEP, IAXIS, C0, Material name, NDVMX (GSDVT2)
    • NDIV, IAXIS, STEP, C0, Material name, NDVMX (GSDVX)
• GMAT - the same constants as in GMAT titles (see above)
• GMIX - the same constants as in GMIX titles
• MATU/MEDU - list of parameters to be appended to the material (MATU) or tracking medium (MEDU) parameter list of standard GEANT3
• NEAR/NEXT/ORD
  • name (character string) and routine specific information:
  • number of content (IN), Length of list, list of neighbours (GSNEAR/GSNEXT)
  • or IAXIS (GSORD)
• POS /POSP
  • volume name (character string)
  • copy number
  • name of the mother volume (character string)
  • name of rotation matrix (character string, NULL if no rotation matrix, xNXT if the last rotation matrix of the detector type or one standard matrix)
  • ONLY/MANY specification (string)
  • x, y, z coordinates and optionally (for GSPOSP) number of parameters and parameter list.
• ROTM - the same constants as in ROTM titles
• SATT
  • volume name (character string)
  • attribute name
  • attribute value
• SENS/MEDI
  • name of the material which is to be declared as sensitive
• TMED
  • tracking medium name (character string) followed by:
  • ISVOL, IFIELD, FIELDM, TMAXFD, STEMAX, DEEMAX, EPSIL, STMIN
• TPAR
  • tracking medium name (character string)
  • parameter name (string)
  • its new value
• VOLU
  • volume name (character string)
  • shape (character string)
  • medium (character string)
  • number of parameters plus parameter list
• 2PNT
  • volume name (character string)
  • name of the mother (character string)
  • the ONLY attribute (character string)
  • number of 2-point volumes to be positioned
  • parameter list of the mother volume
  • coordinates of the first and the last point

The title block for GEOM takes care of special cases of some polygons and polycones (also invoked through the keyword MKPO in title block GEAN). The title block has the following structure:

 
*DO  GEOM  <idn>   -A4CW -c1/80     #. title header line
 :SDET          #. Subdetector keyword name (e.g. CMSE)
   ...
  followed by blocks of data for polycones or polygons
   ...

Each block contains the names of the current volume and the mother volume, the material content of the current volume, number of edges (0 for polycones), number of xy-planes and for each plane, the position with inner and outer radii. In the example

 :BTUB :BEAM  "C_Beryllium"   0.  2.0  0.00  5.85  6.00
                                      75.00  5.85  6.00

a beryllium tube BTUB is positioned inside the volume BEAM. The volume BTUB is constructed making use of a polycone defined through two planes at z = 0 and at z = 75 with inner and outer radii of 5.85 and 6.00 respectively.

As an example we present in Appendix A.5 a full description of the Silicon barrel detector.