Maria Grazia Pia, INFN Genova – CHEP 2001 ow Energy Electromagnetic Physics ow Energy Electromagnetic Physics S. Chauvie,G. Depaola, F. Longo, V. Ivanchenko, P. Nieminen, M.G. Pia on behalf of Geant4 Low Energy Electromagnetic Working Group Budker Inst. Novosibirsk - CERN - Univ. of Cordoba - ESA INFN (Ferrara, Genova, Torino,Trieste) CHEP 2001 Conference Beijing, 3-7 September

Maria Grazia Pia, INFN Genova – CHEP 2001 Courtesy ESA Space Environment & Effects Analysis Section X-Ray Surveys of Asteroids and Moons Induced X-ray line emission: indicator of target composition (~100  m surface layer) Cosmic rays, jovian electrons Geant3.21 ITS3.0, EGS4 Geant4 Solar X-rays, e, p Courtesy SOHO EIT C, N, O line emissions included Low energy e/  models in Low energy e/  models in were triggered by astrophysics requirements

Maria Grazia Pia, INFN Genova – CHEP 2001 Boulby mine Courtesy of NASA/CXC/SAO Bepi Colombo Radiotherapy Brachytherapy Dark matter searches XMM AGN GLAST From deep underground to galaxies From crystals to human beings

Maria Grazia Pia, INFN Genova – CHEP 2001 A growing interest… The activity on Geant4 Low Energy Electromagnetic Physics started in October 1998 l Part of the RD44 electromagnetic category, 1 ESA contractor l Continued as a subset of Geant4 general Electromagnetic Working Group (2 people) l Initially meant to be one of the “ESA modules” for space radiation studies, limited to electron and photon processes The scope of the activity extended soon l Physics: wide set of models l Applications: also HEP, astrophysics, medical… Geant4 Low Energy Electromagnetic Working Group Independent Geant4 Low Energy Electromagnetic Working Group created in April 2000 (9 members initially) 53 members now Contacts in progress with new people interested to collaborate A user a day keeps the doctor away

Maria Grazia Pia, INFN Genova – CHEP 2001 How we operate Rigorous approach to software engineering Rich and transparent physics Goal-directed project management Wide spectrum of development: PhysicsApplications Team Collaboration Outreach Ample coverage of expertise (theory, experimental, software) Emphasis on training of group members Promotion of cross-WG activities Close relationship with user communities Active strategy of information Promotion of technology transfer Working Group Objectives

Maria Grazia Pia, INFN Genova – CHEP 2001 currentstatus Software Process Public URD Full traceability through UR/OOD/implementation/test Testing suite and testing process Public documentation of procedures Defect analysis and prevention etc.… A rigorous approach to software engineering in support of a better quality of the software especially relevant in the physics domain of Geant4-LowE EM several mission-critical applications (space, medical…) A life-cycle model that is both iterative and incremental Spiral approach Huge effort invested into SPI l l started from level 1 (CMM) l l in very early stages: chaotic, left to heroic improvisation Collaboration-wide Geant4 software process, tailored to the WG projects (see talk on Geant4 Software Process by G. Cosmo)

Maria Grazia Pia, INFN Genova – CHEP 2001 User Requirements Posted on the WG web site Elicitation through interviews and surveys l l Useful to ensure that UR are complete and there is wide agreement Joint workshops with user groups Use cases Analysis of existing Monte Carlo codes Study of past and current experiments Direct requests from users to WG coordinators Prototyping l l Useful especially if requirements are unclear or incomplete l l Prototype based on tentative requirements, then explore what is really wanted Various methodologies adopted to capture URs Not only functional requirements, users also ask for l validation l Proof of validation of the physics l Documentation l Examples l Examples of application in real-life set-ups User requirements evolve User requirements evolve …and we should be able to cope with their evolution! Specification: Specification: PSS-05 standard Analysis: Analysis: in WG workshops Maintenance: Maintenance: under configuration management

Maria Grazia Pia, INFN Genova – CHEP 2001 OOAD Rigorous adoption of OO methods  openness to extension and evolution Extensive use of design patterns Booch methodology Technology as a support to physics

Maria Grazia Pia, INFN Genova – CHEP 2001 Algorithms encapsulated in objects Physics models handled through abstract classes Interchangeable and transparent access to data sets Hadrons and ions Open to extension and evolution Transparency of physics, clearly exposed to users

Maria Grazia Pia, INFN Genova – CHEP 2001 Intelligent data: know how to handle themselves through algorithm objects e.g.: interpolation algorithms encapsulated in objects (to let them vary and be interchangeable) Composite pattern to treat different physical entities (e.g. whole atom and atom with shell structure) transparently Data Management Very important domain: physics models based on the use of evaluated databases

Maria Grazia Pia, INFN Genova – CHEP 2001 Photons

Domain decomposition leads to a design open to physics extensions Now fluorescence is implemented only In progress/future: Auger, Coster-Kronig PIXE Atomic relaxation

Maria Grazia Pia, INFN Genova – CHEP 2001 Testing Suite of unit tests (~1 per class) Cluster testing 3 integration/system tests Suite of physics tests (in progress with publications) Regression testing Testing process ­Testing requirements ­Testing procedures ­etc. Physics validation XP practice “write a test before writing the code” recommended to WG developers! Integrated with development (not “something to do at the end”)

Maria Grazia Pia, INFN Genova – CHEP 2001 Electron and Photon processes 250 eV – 100 GeV Validity range: 250 eV – 100 GeV l 250 eV is a “suggested” lower limit l data libraries down to 10 eV l 1 < Z < 100 evaluated data libraries Exploit evaluated data libraries (from LLNL):  EADL (E valuated A tomic D ata L ibrary )  EEDL (E valuated E lectron D ata L ibrary )  EPDL97 (E valuated P hoton D ata L ibrary )  for the calculation of total cross section and generation of the final state Photon transmission, 1  m Pb shell effects GaAs lines Fe lines fluorescence Compton scattering Rayleigh scattering Photoelectric effect Pair production Bremsstrahlung Ionisation + atomic relaxation

Maria Grazia Pia, INFN Genova – CHEP 2001 Photon attenuation: comparison with NIST data waterFe Pb Courtesy of S. Agostinelli, R. Corvo, F. Foppiano, S. Garelli, G. Sanguineti, M. Tropeano Testing and Validation by IST - Natl. Inst. for Cancer Research, Genova accuracy within 1% Low Energy EM l l Standard EM w.r.t. NIST data

Maria Grazia Pia, INFN Genova – CHEP 2001 Polarisation 250 eV -100 GeV y O z x     h h   A C  Polar angle  Azimuthal angle  Polarization vector Integrating over  Sample   - Energy Relation  Energy Sample of  from P(  ) = a (b – c cos 2  ) distribution More details: talk on Geant4 Low Energy Electromagnetic Physics Other Low Energy Polarised Processes under development Sample Methods: Cross section: Scattered Photon Polarization 10 MeV small large 100 keV small large 1 MeV small large Low Energy Polarised Compton

Maria Grazia Pia, INFN Genova – CHEP 2001 Hadron and ion processes Variety of models, depending on energy range, particle type and charge Bethe-Bloch model of energy loss, E > 2 MeV 5 parameterisation models, E < 2 MeV ­ ­ based on Ziegler and ICRU reviews 3 models of energy loss fluctuations ­ ­ Density correction for high energy ­ ­ Shell correction term for intermediate energy ­ ­ Spin dependent term ­ ­ Barkas and Bloch terms ­ ­ Chemical effect for compound materials ­ ­ Nuclear stopping power Positive charged hadrons Positive charged ions Negative charged hadrons Scaling: 0.01 <  < 0.05 parameterisations, Bragg peak ­ ­ based on Ziegler and ICRU reviews  < 0.01: Free Electron Gas Model Parameterisation of available experimental data Quantum Harmonic Oscillator Model ­ ­ Effective charge model ­ ­ Nuclear stopping power ­ ­ Model original to Geant4 ­ ­ Negative charged ions: required, foreseen

Maria Grazia Pia, INFN Genova – CHEP 2001 Some results: protons Straggling Stopping power Z dependence for various energies Ziegler and ICRU models Ziegler and ICRU, FeZiegler and ICRU, Si Nuclear stopping power Bragg peak (with hadronic interactions)

Maria Grazia Pia, INFN Genova – CHEP 2001 Some results: ions and antiprotons antiprotons protons Energy loss in Silicon Ar and C ions Deuterons

Maria Grazia Pia, INFN Genova – CHEP 2001 Application examples advanced examples Three advanced examples developed by the LowE EM WG released in December 2000 as part of the Geant4 Toolkit (support process) Extensive collaboration with Analysis Tools groups (see talk by A. Pfeiffer, Architecture of Collaborating Frameworks) More in progress l l Underground physics and radiation background l l X-ray fluorescence and PIXE l l brachytherapy l l X-ray telescope  - ray telescope Full scale applications showing physics guidelines and advanced interactive facilities in real-life set-ups

Maria Grazia Pia, INFN Genova – CHEP 2001 User applications Courtesy of S. Magni, Borexino Courtesy of A. Howard, UKDM ZEPLIN III Dark Matter, Boulby mine No time to mention them all! See also other talks: Simulation for astroparticle experiments (this session) From HEP computing to bio- medical research (plenary) Courtesy of F. Foppiano, M.Tropeano, IST Solar system explorations Courtesy SOHO EIT Cosmic rays, jovian electrons Solar X-rays, e, p Courtesy P.Truscott, DERA Courtesy of R. Nartallo, ESA XMM X-ray telescope RGS EPIC

Maria Grazia Pia, INFN Genova – CHEP 2001 Conclusions New physics domain in HEP simulation Wide interest in the user community A wealth of physics models A rigorous approach to software engineering Significant results from an extensive validation programme A variety of applications in diverse domains

Maria Grazia Pia, INFN Genova – CHEP