Maria Grazia Pia, INFN Genova Advanced Examples Maria Grazia Pia, INFN Genova on behalf of the LowE/advanced examples WG Geant4  Review, CERN, October 2002

Maria Grazia Pia, INFN Genova 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 address a wide set of inter-related issues –the usage of simulation components in a typical experimental environment –complementary “interactive” features (graphics, G/UI) –analysis histogramming, plotting the physics results of the simulation while it is still running etc… user support They represent a valuable form of user support playground They represent a playground to explore experiments’ requirements and to evaluate prototype solutions –…and to make sure that a solution that may be fine for a specific experiment would be fine for the whole Geant4 user community…

Maria Grazia Pia, INFN Genova Collaboration: G4 + experiments Advanced examples are developed in close collaboration with user groups –users bring the knowledge of their experimental domain –Geant4 collaborators bring the knowledge of Geant4 and of its wide application domain The synergy produces a valuable reference for other users –GLASTgammaray_telescope –GLAST simulation started from the gammaray_telescope example –underground_physics Gran Sasso –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 –the reference is often of general interest, not only specific to the original experimental problem e.g. question from a cosmic ray experiment user finds a response in underground_physics

Maria Grazia Pia, INFN Genova History 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. WG soon after its creation (spring 2000) not –the topics of the advanced examples are not necessarily related to LowE e.m. –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 3 “LHC-like” advanced examples have been agreed –originating from test-beam simulations –2 are at an advanced development stage …and more advanced examples are spontaneously proposed by users!

Maria Grazia Pia, INFN Genova 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 “what they want the software to do” The ex.-developers prepare a description of “what they want the software to do” URD –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)

Maria Grazia Pia, INFN Genova 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 initial code, and donate them the design models for further evolutions The design is reviewed with Geant4 collaborators –suggest improvements, better usage of toolkit components etc. The implementation is done in close collaboration with Geant4 and Anaphe experts The code is tested by the ex. development group Of course, all this is carried on through an incremental and iterative process…

Maria Grazia Pia, INFN Genova 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 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 provided by the ex.-developers –this is the most difficult thing to get done! The ex.-developers update the requirements traceability matrix –a lot of effort falls on the LowE WG coordinator… The LowE WG coordinator assemble the existing material into a cohesive documentation –links to example documentation, URD, design diagrams, results, traceability etc.

Maria Grazia Pia, INFN Genova 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 significant workload –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”

Maria Grazia Pia, INFN Genova Analysis real life In real life simulation is often accompanied by analysis –histograms, ntuples to plot relevant physics distributions 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 Close collaboration with the AIDA team Very valuable support to ex.-developers and users by the Anaphe team

Maria Grazia Pia, INFN Genova Underground physics A liquid Xenon cell, with a typical underground background environment Record scintillation light in PMs neutrons ionsscintillationradioactive decay 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 primary generator Complex primary generator (GPS) LXe GXe PMT mirror source

Maria Grazia Pia, INFN Genova  telescope trackercalorimeterveto A tracker + a calorimeter + a veto counter Standard electromagnetic processes triggerdigitised Example of how to build a simple trigger out of digitised signals How to plot histograms with physics distribution while the simulation is running

Maria Grazia Pia, INFN Genova 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 space radiation background studies 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.

Maria Grazia Pia, INFN Genova X-ray fluorescence X-ray analysis 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 sample detector beam Scattered photons Fe lines GaAs lines

Maria Grazia Pia, INFN Genova brachytherapy dose distributions 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

Maria Grazia Pia, INFN Genova In preparation Gravitational wave experiment –Space charging LHC-like test beam set-ups –Atlas-like forward calorimeter –CMS-like composite calorimeter –LHCb-like RICH Radioprotection –Contamination from radioactive isotopes in human body (and environment?) IORT –Model of a compact accelerator …and more to come modular RunManager for integration in experiment framework –proposed at the G4workshop, discussed yesterday: modular RunManager for integration in experiment framework

Maria Grazia Pia, INFN Genova Conclusions The advanced examples have been created in response to typical user questions They offer (simplified) solution to real-life experimental situations They represent an effective means of user support They are a playground –to better understand experiments’ requirements –to explore how Geant4 addresses specific experimental issues Users’ feedback is very positive More information in