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Geant4 for gamma-ray spectrometry. Andi Hektor andi@ut.ee GEANT4 WORKSHOP at HIP Oct 30-31, 2003. Outline. Introduction: our detector system Gamma-ray spectrometry Detection limits Why Geant4? M odel and some examples Results An u topia of a Geant4 user

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Geant4 for gamma-ray spectrometry


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    1. Geant4 for gamma-ray spectrometry Andi Hektor andi@ut.ee GEANT4 WORKSHOP at HIP Oct 30-31, 2003

    2. Outline • Introduction: our detector system • Gamma-ray spectrometry • Detection limits • Why Geant4? • Model and some examples • Results • An utopia of a Geant4 user • Summary and some acknowledgements

    3. REAL TIME RADIATION SURVEILLANCE EQUIPMENT FOR THE UNMANNED AERIAL VEHICLE RANGER A. Hektor, K. Kurvinen, R. Pöllänen and P. Smolander STUK - Radiation and Nuclear Safety Authority P.O.Box 14, FIN-00881 HELSINKI, Finland petri.smolander@stuk.fi M. Kettunen Finnish Defence Forces Technical Research Centre P.O.Box 5, FIN-34111 LAKIALA, Finland J. Lyytinen Helsinki University of Technology, Laboratory of Lightweight Structures P.O.Box 4100, FIN-02015 HUT, Finland Funded by: SCIENTIFIC ADVISORY BOARD FOR DEFENCE

    4. Mobile gamma-ray detector • Tracking of a release plume • Time critical, decision aid for initial response, radiation safety of the air crew • Fallout mapping • After the initial emergency, long term risk management • Locating of a point source • Lost sources, smuggling and terrorism Unmanned aerial vehicle (UAV) is an excellent choice from the radiation safety stand point

    5. Ranger Tactical UAV Operated by FDF Range: 150 km Endurance: 5 hrs Payload: 40 kg Catapult take-off Landing on skids Fully autonomous or remotely piloted Unmanned aerial vehicle Photo: Lauri Ahonen, FDF

    6. Detector system Connected to the UAV NaI(Tl)Scintillationdetector GM baseddose rate meter Pilot camera Temp + Rh sensor Data acquisition computer w/GPS CZT detector Air volume sensor Sampling unit Tetra Radio Secondary data link to the VIRVE network

    7. Geometry of the detector system Light weight structure • Airworthiness above all • Vibration attenuation • Temperature control • Modularity • Easy installation Jari Lyytinen, HUT/LLS

    8. Installation of the detector

    9. A gamma-ray spectrometer

    10. Source NaI(Tl) Physics in gamma-ray spectrometer • Photoelectric absorption • Compton scattering • Pair production • Multiple scattering • Electron ionisation • Bremsstrahlung • Positron annihilation

    11. Physical properties of NaI(Tl) 1/2 From http://www.scionixusa.com/crystals.html

    12. Physical properties of NaI(Tl) 2/2 Emission spectra of some materials, from http://www.scionixusa.com/crystals.html

    13. Detection limits of the detector? 1/2 3D 2D 1D Different type of sources, long distances between the source and detector, high speed of the detector, energy resolution

    14. Detection limits of the detector? 2/2 • Analytical methods • Quite complicated • Numerical calculations • Monte Carlo simulations • Many packages are available: DPM, EA-MC; EGS4, EGS5, EGSnrc, FLUKA; Geant3, Geant4; GEM; HER-MES; LAHET; MARS; MCBEND; MCNP, MCNPX, A3MCNP, MCNP-DSP, MCNP4B; MF3D; MVP, MVP; -BURN; MONK, MORSE; NMTC, etc. • Easy to use (!) • Why Geant4? • Object-oriented and fast (C++) • Many integrated modules • Some nice memories and experiences from high energy physics

    15. Geant4 • Supported physics? • Structure of Geant4? • C++? • Examples? • Support: manuals, user forums, etc?

    16. 3D-model of our detector in Geant4 3D-model

    17. Some examples of the Monte Carlo simulations in Geant4 1/4 Example 1 Example 1 Energy of the gammas: 662 keV (Cs-137) Number of the gammas: 15

    18. Some examples of the Monte Carlo simulations in Geant4 2/4 Example 2 Energy of the gammas: 662 keV (Cs-137) Number of the gammas: 15

    19. Some examples of the Monte Carlo simulations in Geant4 3/4 Example 3 Energy of the gammas: 662 keV (Cs-137) Number of the gammas: 15

    20. Some examples of the Monte Carlo simulations in Geant4 4/4 Example 3 Energy of the gammas: 662 keV (Cs-137) Number of the gammas: 15

    21. Constructing of our detector in Geant4 Ideas for physics and input data CAD model Physics List Geometry Input parameters Kernel Analysis Visualization Histograms Visualization files Tracks Kernel logs Analysis

    22. Files for our Geant4 silmulations GammaSpecSTUK.cc- main source of our detector GNUmakefile - make file for compilation include/ - include files README - informative README file vis.mac - default input parameters src/ - source files GammaSpecSTUKDetectorConstruction.cc - detector geometry GammaSpecSTUKEventAction.cc GammaSpecSTUKEventActionMessenger.cc GammaSpecSTUKPhysicsList.cc - physics in detector GammaSpecSTUKPrimaryGeneratorAction.cc GammaSpecSTUKRunAction.cc GammaSpecSTUKSteppingAction.cc GammaSpecSTUKSteppingVerbose.cc GammaSpecSTUKVisManager.cc

    23. For example, air definition in the detector construction file … G4VPhysicalVolume* GammaSpecSTUKDetectorConstruction::Construct(){ G4String name, symbol; G4double a, z, density; G4int ncomponents, natoms; // Air - environment around the detector G4Element* elN = new G4Element("Nitrogen", "N", z=7.,a=14.01*g/mole); G4Element* elO = new G4Element("Oxygen" , "O", z=8., a=16.00*g/mole); density=1.29*mg/cm3; G4Material* Air = new G4Material("Air", density, ncomponents=2); Air->AddElement(elN, 70*perCent); Air->AddElement(elO, 30*perCent); …

    24. A result The peak of Cs-137 (662 keV); the location of the source: 10 cm in the x-direction; number of the events in the detector: ~200 000

    25. An utopia of a Geant4 user • “Parallel-Geant4” • “Continuous project development”

    26. 1 2     “Parallel-Geant4” • Monte Carlo methods • Some projects is running for Geant4 • Geant4 and Grid-technology

    27. “Continuous project development” Initial ideas Ideas, model Analysis Simulations Final results

    28. “Continuous project development” Ideas for physics and input data CAD model Physics List Geometry Input parameters Kernel Analysis Visualization Histograms Visualization files Tracks Kernel logs Analysis

    29. Summary • Geant4 is a great MC package • You do not have to be an expert of C++ • Most of needed physics is there (in our case) • Some nice results for our project • Graphical interface? • Parallel version? • Development of models in CAD (XML, VRML, etc) and Geant4 together

    30. Acknowledgements • STUK • HIP • SCIENTIFIC ADVISORY BOARD FOR DEFENCE IN FINLAND for funding