The HADES Geometry Interface

1
The HADES Geometry Interface

• Overview of the initialization concept in HADES
• File (ASCII) interface for simulation
• Geometry
• ROOT / GEANT3 input format
• HADES input format
• Media
• Outlook

2
Overview of the initialization concept in HADES
WebDB GUI
ASCII Files
ASCII, ROOT Files
HYDRA

• HGEANT

ROOT TGeoManager
3
ROOT / GEANT3 input format for the geometry

• Creation of a volume (TGeoVolume)
• Volume name
• Shape
• Shape parameters
• Medium
• Positioning of the volume in a mother (TGeoNode)
• Mother
• Transformation (position and rotation matrix)

pipe_1 0 world 0.000 0.000
5.000 1. 0. 0. 0. 1. 0. 0. 0.
1. carbon TUBE 0.000 0.550
5.000 fi pipe_vac_1 0 pipe_1 0.000
0.000 0.000 1. 0. 0. 0. 1. 0. 0.
0. 1. vacuum TUBE 0.000 0.500
5.000 fi target 1 World Causes overlap!
0.000 0.000 0.000 1. 0. 0. 0.
1. 0. 0. 0. 1. gold TUBE 0.000 0.25
0.025 fi
Most shapes Geometrical center of daughter is
positioned in geometrical center of mother.
TUBE
Change of the size of the mother
Repositioning of mother and of all its
daughters
4
HADES input format for the geometry

• The position of the local coordinate system of a
  volume must NOT be the geometrical center.
• The positioning of the daughter is independent of
  the size and shape of the mother.
• The transformation describes the position of the
  local coordinate system of the daughter relative
  to the coordinate system of the mother.

.
.
pipe_vac_1 pipe_1 TUBE vacuum 0. 0. -50. 0.
5. 0. 0. 100. 0. 0. 0. 1. 0. 0. 0. 1.
0. 0. 0. 1. //
target pipe_vac_1 TUBE gold 0. 0.
-0.25 0. 2.5 0. 0. 0.25 0. 0. 0. 1. 0. 0.
0. 1. 0. 0. 0. 1.
z/mm
-50 0 100
pipe_1 cave TUBE carbon 0. 0. -50. 0. 5.5
0. 0. 100. 0. 0. 0. 1. 0. 0. 0. 1. 0.
0. 0. 1. //

5
Some shapes

• BOX, TRAP, TRD1 described by the 8 corners

5
7
2
3
y
z
6
8
x
1
4
TUBE, TUBS, CONE, CONS center of front and
back circle, inner and other radius

phi
section
.
.
Advantage more flexibility, closer to
technical drawings and analysis coordinate
systems Disadvantage more points then really
needed (more typing)
6
Input format for media
Name
Number of components
A
Z
Density
Relative weights

• carbon 1 12.011 6.0 2.265
• 0 1 30. .001
• 0
• TRDgas 3 131.30 12.01 16. 54. 6.
  8. 5.4476e-3 0.85 0.0405 0.1095
• 1 1 30. .001
• 0

Maximum field
Sensitivity flag
Field flag
EPSIL
Number of Cerenkov parameters
7
Outlook

• Integration of the shared library or the classes
  into the CBM framework within the next 2 3
  weeks
• Documentation of the input formats
• Conversion of existing geometry files into the
  new format (converter exists)
• Summer of this year Oracle Database framework
  and interfaces, including sophisticated version
  management
• (only if new format is accepted)