Geant4 User Requirements: inputs from ESA

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Geant4 User Requirements inputs from ESA
Proto-Technical Forum Vancouver, 5 Sept 2003

• E.Daly, H.Evans, A.Keating, P.Nieminen,
  G.Santin
• Space environments end effects analysis
• ESTEC
• RHEA System SA

• Items proposed for the discussion
• Processes Access to the Track properties before
  the processes
• Processes development of X-ray surface
  processes
• Geometry construction input from external
  models
• Physics LHEP_BIC_HP physics list

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1. Access to Track properties before the
processes I context

• Context
• Radiation Effects to components
• Damage correlated to
• Total Ionising Dose (TID) and to
• Non Ionising Energy Loss (NIEL)
• Non Ionising Energy Loss (NIEL) studies
• Cumulative effect caused by protons, neutrons,
  electrons, pions
• Possible approaches to compute NIEL
• Macroscopic (tabulated NIEL coefficients)
• Microscopic study
• see Ana Keatings talk, Users Presentations
  Session
• Technically the microscopic approach requires
• Study of the effects of the process to the
  incident track
• The requirements

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1. Access to Track properties before the
processes II requirement
AlongSteps

• Time flow
• PreStepPoint
• Continuous Processes
• Cont. Proc. 1
• Cont. Proc. 2
• Discrete Process
• PostStepPoint

Post Step
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1. Access to Track properties before the
processes III technical requirements

• During the tracking
• before executing the present DoIt code, execute
  a method that saves the Track in a temporary
  trackBeforeTheDoIt variable
• This method could be
• Common to all processes
• Implemented in G4VProcess
• The saving operation could be called
• By each process as a first action before the
  present code
• By the Tracking Mgr before the call to each
  DoIt
• easier, less changes in the code
• As an option, if time consuming
• Copy of the Track involves
• Copy of the G4Track itself
• Copy of the DynamicParticle

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2. Development of X-ray surface processes I

• X-ray processes at the surfaces
• in particular surface reflection at grazing
  angles, but with a more general approach.
• Potential interest for X-ray telescope mirrors
  (the present XMM or the future XEUS)
• Also for some other studies
• effects of collimators in front of detectors
  sensitive to X-rays
• applications in space, medical physics, etc.

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2. Development of X-ray surface processes II

• Process structure similar to the optical photon
  reflection/refraction/absorption
• Technical details
• Peter Gumplinger contacted
• Machinery is mostly already there
• BorderSurface, OpticalSurface, MaterialPropertiesT
  able,
• Development started
• Small modifications in the OpticalBorderProcess
  would allow to inherit Optical and X-ray
  processes from a base class with useful common
  features

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3. Geometry construction input from external
models I

• At present
• Geometry models can be input via coding, GGE
• Most major experiments developed their own
  interface to geometry data
• Non experts find geometry modeling the first
  major obstacle to the use of Geant4
• Existing models are not easy to re-use
• Models developed via C coding require cutpaste
• Models developed via GGE?
• GUI
• Simple Graphic User Interfaces (GUI) are
  appealing to the novice users
• Complete, user friendly, precise, powerful GUIs
  are not easy to develop and maintain
• Standards for geometry modeling already exist in
  the engineering world
• Engineering CAD tools capabilities are difficult
  to reproduce with non professional graphic tools

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3. Geometry construction input from external
models II

• For space applications, its common practice to
  start from existing engineering CAD models
• In most cases these cannot be imported via the
  existing STEP interface
• The most used CAD tool seems to be CATIA
• even very simple CATIA files cannot be imported
  into a Geant4 model.
• An improvement in the STEP interface would be
  more than welcome.
• As a complement to that, the development of a new
  more complete STEP standard format is ongoing at
  ESA, with a time scale of one year or two
• A similar extension to STEP has ben done already
  for "Thermal Analyses for Space" (STEP-TAS).
• The Space Environment extension will have as a
  guideline the compatibility with the Geant4
  material description model and with the ESABASE
  geometry format.

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3. Geometry construction input from external
models III

• UI and ASCII files
• materials and volumes could be indroduced via
  interactive commands or ASCII files.
• It would allow precise definition and positioning
  of the volumes without losing the richness of the
  Geant4 geometry description and visualisation.
• Possible solutions
• dedicated scripting commands to introduce
  materials and volumes (a la GATE) and/or
• an interface to input the geometry information
  from "easy to read" ASCII files (such as
  XML/GDML).
• Such macros or files could also be used as an
  interface between external tools (and old MC
  tools) and Geant4.
• The main requirements for such interface would be
• the definition of a standard language
• its completeness (for materials, volumes and
  visualisation options)
• a long term maintenance and support
• Harmonisation
• In general, the harmonisation of the Geant4
  projects for the geometry input format, with
  other present and future projects which require a
  geometry description (engineering and scientific
  tools) would be appreciated.