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Jornadas LIP 2003, Lisboa, 20-21 de Dezembro Aplicações de Geant4 em experiências de Astropartículas M.C. Espírito-Santo, P. Gonçalves, M. Pimenta, P.

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Presentation on theme: "Jornadas LIP 2003, Lisboa, 20-21 de Dezembro Aplicações de Geant4 em experiências de Astropartículas M.C. Espírito-Santo, P. Gonçalves, M. Pimenta, P."— Presentation transcript:

1 Jornadas LIP 2003, Lisboa, de Dezembro Aplicações de Geant4 em experiências de Astropartículas M.C. Espírito-Santo, P. Gonçalves, M. Pimenta, P. Rodrigues, B. Tomé, A. Trindade

2 The main objectives of the LIP-ESA contract Radiation Interaction Simulations for High-Energy Astrophysics Experiments EUSO and AMS 1 are: to allow/promote the participation of Portuguese groups in the Geant4 activities related to space applications. to develop a software framework for application of Geant4 in the first instance to astroparticle experiments (EUSO and AMS) on the ISS. to perform detailed inter-comparison with results from Monte Carlo and analytical codes and experimental data. Introduction The team joins collaborators from AMS, EUSO and Medical Physics LIP groups ESA/ESTEC Contract No /03/NL/LvH/bj 1 ESA/ESTEC Contract No /03/NL/LvH/bj

3 Contract deliverables Monthly progress reports 2 Technical Notes (KO+3 months, KO+12 months) Mid-term review meeting at LIP premises (held on October 15 th ) Final presentation (to be held at ESTEC) Article for publication in ESA´s bulletin WWW site for the project IEEE Nuclear Science Symposium/Medical Imaging Conference, October, 2003, Portland, Oregon, USA"

4 Simulation Requirements Simulation of AMS/RICH and EUSO/ULTRA sub-detector geometries Interface with different primary event generators Cosmic-ray flux in high-altitude orbit Atmospheric cosmic-ray flux at ground-level Accelerator beam phase-space data Simulation of readout electronics, signal digitisation and event reconstruction OO technology for event data persistency and data analysis

5 Simulation Organization Analysis: ROOT Radiation Transport: GEANT4 Signal Digitization: DIGITsim Event Storage: ROOT I/O Code Management System: CVS System GEANT4 DIGITsim ROOT Analysis ROOT I/O CVS Code Management

6 Framework Highlights Ability to accommodate different geometry organizations General Particle Source (GPS) developed by ESA for primary particle sampling (ISS orbit or Earth surface) Physics Lists: Electromagnetic Standard Physics (for leptons and hadrons) Low Energy Electromagnetic Physics for sensitive detectors Optical transport of scintillation and Cherenkov light, Rayleigh dispersion, bulk attenuation (plus WLS process for GEANT4.6.0 release) UNIFIED optical boundary model No hadronic modes for now (physics lists for air showers are under test by beta- testers)

7 AMS/RICH and EUSO/ULTRA related applications

8 Simulation of an ULTRA station Internal walls are coated with white diffusing paint Plastic scintillator is NE102A PMTs are Phillips XP3462B

9 AMPADC PMT 1. Energy deposition in the scintillator, photon generation 2. Light propagatio n and collection 3. Photoelectron production and signal generation 4. Signal shaping and amplification 5. Time sampling, analog to digital conversion GEANT4Space DataFrame The LIP-PAD Simulation scheme

10 … a 80MeV electron

11 Simulation of the ULTRA UV telescope (I) Photomultiplier Fresnel lens: 457 mm diameter 457 mm focal length 5.6 grooves/mm UV transmitting acrylic Aluminum housing

12 Simulation of the ULTRA UV telescope (II) (Fresnel lens implementation in the simulation framework) (work in progress...)

13 AMS/RICH radiator simulation

14 AMS/RICH aerogel studies Improve description/understanding of light scattering in aerogel Introduce realistic modelling of aerogel surface Mapping of aerogel surface using Atomic Force Microscope (ongoing measurements) Upgrade related classes of Geant4.

15 Sumário As actividades realizadas no âmbito do contracto LIP-ESA permitiram alargar competências já existentes no LIP no grupo de Física Médica aos grupos envolvidos em experiências de Astropartículas. Foram identificadas áreas de intervenção para o desenvolvimento do código de Geant4. A colaboração Geant4 manifestou já interesse em aplicações desenvolvidas utilizando o framework descrito.

16 The virtual ULTRA station...

17 Summary and Future The simulation of a station of the ULTRA ground array detector was implemented using the SpaceGEANT4 framework. Update of the ROOT persistency class is foreseen to include a TClonesArray of StoreOpticalPhoton objects. Explore the SpaceGEANT4 framework in other applications, namely in the simulation of: Experimental setup for fluorescence measurements Čerenkov light in the EUSO Fresnel lenses from space environment radiation Possible effects of material deposition on EUSO lenses Electronics response Simulation of the optics of the ULTRA U.V. detector Fresnel Lens + light collector

18 Implementation in the SpaceGEANT4 framework DetectorConstruction Geometry definitions, material properties, optical constants and properties. SteppingAction and TrackingAction Concrete user classes that allow to manipulate information retrieved from each step/track. Information is transfered to EventAction, for filling of persistent class. PrimaryGeneratorActionMessenger Dedicated messenger class to promote particle source position and momentum direction scannings. EventForTree ROOT persistent class for data storage DIGITsim Dedicated standalone digitization framework (see next talk by M.C. Espírito Santo)

19 The NE102A scintillator in the simulation: Polystirene based H:C ratio = 10:9 density =1.032 g/cm3 Refractive index = 1.58 Absorption length =160 cm Light yield=10000 Photons/MeV

20 NE102A emission spectrum: The scintillator emission spectrum was included in the simulation as an optic material property max=423 nm

21 Optical boundaries UNIFIED model chosen Scintillator-Air interface: TYPE : dielectric-dielectric FINISH : ground Air-Painted aluminium interface: TYPE: dielectric-dielectric FINISH : GroundFrontPainted Reflectivity = 1 (to be updated)

22 Event data storage Events are stored under a ROOT Tree organization EventForTree is the ROOT persistent class For each event, the EventForTree object contains namely: Primary particle initial position and momentum Total energy deposited in the scintillator Number of detected optical photons TClonesArray of StoreScintHit objects (TClonesArray of StoreOpticalPhotons objects – to be implemented) StoreScintHit Energy x,y,z StoreScintHit Energy x,y,z...

23 Energy deposition in the scintillator (80MeV electrons)

24 Source Position (cm) Deposited energy (MeV) # outgoing photons Light collection uniformity

25 Aerogel tiles n=1.03 Clarity= 11.3 cm x 11.3 cm x 3.0 cm, gap 0.1 cm Variable number NTilesx x NTilesy Plexiglas foil n=1.49 ( =400 nm) below the Aerogel tiles ( size depends on NTilesx x NTilesy ) Aerogel Plexiglas

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