Core Framework 

a framework  has to be set up that

  • builds under Java 1.4 (Maven, ant,....)
  • builds with gcj  (make)
  • reads xml files
    • initially use compact format
    • gradually extend/modify as needed
  • drivers need to read xml and implement gear
  • drivers should create geometry elements
    • for detailed view (low level)
    • for tracking view (mid level)
  • initially export to GDML/LCDD should be suported

optionally some wrapping C++ code should be provided that allows to use LCGO in a C++ programm w/o having to rely on references to Java libraries, e.g. for the properties interface


  • need to understand garbage collection for java and C++ objects allocated on the stack and on the heap and passing object between java and c++

Material Database

a material data base is needed that

  • consists of the known materials
  • has all the material properties needed for dE/dx
    • A, Z (mean values) , X0, Interaction length,....
    • check geant4/geant3 which these are
  • is extensible by the user in input xml files
  • provides material objects assigned to volumes (tracking) that give
    • material properties
    • dEdx( PDG, p , flightlength )
    • optionally: dEdx( PDG, p , tracjectory ) ?
  • material properties/names should be consistent
    • with geant4
    • NIST database (the same ?)

Field map

LCGO needs to provide a mechanism for field maps

  • should allow simple field definitions in xml file, e.g.
    • <BField x="0.0" y="0.0" z="4.0" unit="Tesla"/>
    • or better: <BField x="0.0" y="0.0" z="4.0*Tesla" />  (see System of Units)
  • should allow arbitrary field map from file, e.g.
    • <BFIeld file="http://some.server.anywhere/"/>
  • need well defined file format and corresponding implementation class
  •  need well defined simple interface, e.g.
    • interface Field { public Vector3D at( Vector3D x) ; }


Readout Properties

LCGO drivers need to provide an implementation of an interface to query cellIDs, positions and neighbors:

  • cellId <-> position
  • cellid range (noise simulation)
  • cell sizes
  • neighbors

Geometry Elements

we need a full set of geometry classes that allow

  • to construct the detailed low level view of the detector
  • are used to create other representations
    • geant4
    • HepRep
  • all classes currently available in geant4 should be represented - ideally with the same interface
    • shapes (Box, Tube, Polycone,....)
    • logical volume (with material...)
    • physical volumes with placement,i.e.
      • rotation
      • translation
      • parent volume
  • initially the volume heirarchy just needs to be static in order to allow creation of other representations
  • issues/requiremnents
    • names
    • copy numbers
    • sensitive detectors
    • visualization attributes
    • user defined attributes

Tracking Geometry

for the tracking (pattern recognition and fitting) a somewhat simplified representation of the detector volumes is needed with

  • averaged material (see material, dEdx)
  • simple shapes only:
    • boxes - planes ?
    • tubes - cylinders ?

this tracking geometry should allow to compute:

  • intersection with given trajectory
    • line
    • helix
    • ...  


 the mid and high level view of the geometry should be an extension of the current GEAR API

  • should allow to represent current detector concepts' subdetectors
  • provide high level view as needed for
    • reconstruction
    • digitization
  • should provide the geometrical functionality as needed for tracking
  • should be the interface all client programs use to get information from LCGO (except low level view)


 need to review what is currently in GEAR and define what is missing !


System of Units 

it is probably desirable to have a well defined system of units a la Geant4, so that every quantity comes in the properly defined unit. So that one can write code, such as:

    cout << "  length of TPC [cm]:  " << lcgo->getTPCParameters()->getLength() / cm  << endl ;

Vectors and Matrices 

need to define classes for vectors and matrices (symmetric) that are used throughout LCGO (and LCIO !?)

  • 3d vectors
  • rotations 3d
  • translations (3d vectors)
  • 4 vectors (in LCGO ?)
  • matrix
  • symmatrix
  • ... 


  • No labels