Advanced Examples Maria Grazia Pia, INFN Genova on behalf of the LowE-advanced examples WG http://www.ge.infn.it/geant4/examples/index.html Geant4 D Review, CERN, October 2002

Advanced examples Advanced examples are complete applications, corresponding to [simplified] typical real-life experimental situations e.g. a test-beam set-up, a module of a detector etc. They represent a valuable form of user support They are developed in close collaboration with user groups Users bring the knowledge of their experimental domain Geant4 collaborators bring the knowledge of Geant4 The synergy of the two sides produces a valuable reference for other users They are also playgrounds to identify new user requirements, or to verify the suitability of Geant4 for application to specific experimental problems They illustrate not only the usage of simulation components in a typical experimental environment, but also of complementary “interactive” features, as needed in every-day life graphics, (G)UI, histogramming, plotting the physics results of the simulation while it is still running etc…

The historical path A directory examples/advanced was created in geant4 since the very first production release in December 1998 The actual development of Geant4 advanced examples was first proposed by the LowE e.m. Working Group soon after its creation in spring 2000 the topics of the advanced examples are not necessarily related to LowE e.m. physics e.g. the currently LowE e.m. WG supports an example on LHC calorimetry, and the main LowE support comes from collaborators in a dark matter experiment! this is an example of the collaborative spirit at the base of Geant4 The first 3 advanced examples were released in December 2000 Since then, 2 other advanced examples have been released 2 new advanced examples are at an advanced development stage 3 “LHC-like” advanced examples have been agreed …and more are spontaneously proposed by users!

The process: inception Advanced examples are proposed either spontaneously by experimental groups on topics they consider of interest or by members of the Geant4 Collaboration, as a response to identified needs of user support (in which case a “volunteer” collaborating user group must be found… which is not always easy!) The proposed examples are presented to the TSB for inclusion in a future Geant4 release In several cases the advanced examples have been proposed initially as “workshop projects” in the annual Collaboration Workshop, then evolved into longer term projects The ex.-developers prepare a description of “what they want the software to do” which the LowE WG transforms into a simple URD to establish the requirements for the example (the URD is then maintained by the LowE-advanced ex. WG)

The process: construction Ex.-developers should provide at least an architectural design of the example, in response to the URs in practice, users are often not familiar with OOAD… so, pragmatically, we reverse engineer their code, and donate them the design models for further evolutions The design is reviewed with Geant4 collaborators we suggest improvements, better usage of toolkit components etc. The implementation is done in close collaboration with Geant4 and Anaphe members through the assistance of the LowE WG coordinator, example developers are put in contact with Geant4 experts to help them in the specific problems The code is tested by the ex. development group Of course, all this is carried on through an incremental and iterative process…

The process: deployment The code is reviewed together with Geant4 collaborators we would like to do more code reviews, but the resources are limited… The examples are tested against the candidate global release tag prepared by the Release Manager at the end of the system testing phase A documentation, consisting of a README + web page(s), is prepared by the ex.-developers The ex.-developers update the requirements traceability matrix The LowE WG coordinator assemble the existing material into a cohesive documentation links to example documentation, URD, design diagrams, results, traceability etc.

The process: maintenance Advanced examples must be maintained evolutions in Geant4, in AIDA, in the supported platforms, in the user requirements etc. Often the whole workload of maintenance falls on the LowE WG it is a significant workload as well as the support during the construction phase Advanced examples facilitate the user support process Often, the response to a user question is “look into advanced example X, class Y, and you’ll find a solution to a problem quite similar to yours”

Analysis In real life simulation is often accompanied by analysis Histograms, ntuples to plot relevant distribution resulting from the simulation UR: possibility to plot histograms while the simulation is running, to monitor whether everything looks fine, or to decide when to stop the accumulation of statistics All advanced examples adopt AIDA (Abstract Interfaces for Data Analysis) To avoid introducing into Geant4 dependencies from any specific analysis tool Users can choose their preferred analysis system (without having to change one single line of code) by loading the appropriate shared library Documentation in http://www.ge.infn.it/geant4/examples/analysis.html Close collaboration with the AIDA team Very valuable support to ex.-developers and users by the Anaphe team

Underground physics mirror LXe GXe source PMT A liquid Xenon cell, with a typical underground background environment Record scintillation light in PMs Physics: neutrons, LowE processes for ions, scintillation, radioactive decay module etc. Full lab geometry (important for n scattering) Cavern + door, cupboards, desks in the experimental environment Xenon vessel accurately reproducing a real prototype Complex primary generator (GPS) LXe GXe PMT mirror source

X-ray fluorescence Test beam set-up of a typical X-ray analysis A photon beam impinging on a material sample; the fluorescence spectrum of the material is measured by a semiconductor detector Physics: Low Energy processes, atomic relaxation Scattered photons Fe lines GaAs lines sample detector beam

g telescope A tracker + a calorimeter + a veto counter Standard electromagnetic processes Example of how to build a simple trigger out of digitised signals How to plot histograms with physics distribution while the simulation is running

X-ray telescope The first advanced example Originally a “workshop project” (Geant4 Workshop 1999, hosted by ESA) A module of a Chandra/XMM-like telescope Physics for space radiation background studies Well documented example of how to use a variety of visualisation drivers, various (G)UI options, GGE, GPE, histograms, ntuples etc.

brachytherapy A general purpose application for the calculation of dose distributions from a radiotherapy source Fancy geometry to configure different brachyterapy techniques in the same application How to create/destroy/replace a geometry at run-time Low energy electromagnetic processes for precise calculation of dose distribution Developed in collaboration with cancer research groups in hospitals

In preparation Gravitational waves experiment Space charging LHC-like test beam set-ups Atlas-like electromagnetic calorimeter CMS-like electromagnetic calorimeter LHCb-like RICH Radioprotection Contamination from radioactive isotopes in human body (and environment?) IORT Model of a compact accelerator …and more to come

More information in http://www.ge.infn.it/geant4/lowE/index.html Conclusions The advanced examples have been created in response to typical user questions They offer (simplified) solution to real-life experimental situations They offer a valuable user support GLAST simulation started from the gammaray_telescope example underground_physics (developed by UKDM) has become the reference for many experiments at the Gran Sasso Lab brachytherapy has become a “classic” for radiotherapic dosimetry Users’ feedback is very positive More information in http://www.ge.infn.it/geant4/lowE/index.html