20 February 2002

Presentation Transcript

Low-Energy Electromagnetic Processes in P. Nieminen (ESA-ESTEC) http://www.ge.infn.it/geant4/lowE/Geant4 Users' Workhsop, SLAC

Content s Introduction Electron and photon low-vitality electromagnetic procedures in Geant4 Hadron and particle low-vitality electromagnetic procedures in Geant4 Conclusions Geant4 Users' Workhsop, SLAC

Dark matter pursuit, Fundamental material science High Energy Physics Radiotherapy, brachytherapy Low-Energy e.m. a pplications Neutrino material science Spacecraft interior charging examinations Radiation impacts investigation in X-and g - beam astrophysical observatories Mineralogical studies of Solar System bodies Antimatter tests

E lectron and photon forms Energy shorts Geant3.21 10 keV EGS4, ITS3.0 1 keV Geant4 "standard models" -Photoelectric effect 10 keV -Compton effect 10 keV -Bremsstrahlung 1 keV -Ionization ( d - rays) 1 keV -Multiple scattering 1 keV Geant4 low-vitality models 250 eV Geant4 Users' Workhsop, SLAC

Cosmic beams, jovian electrons X-Ray Surveys of Solar System Bodies Solar X-beams, e, p Geant3.21 ITS3.0, EGS4 Courtesy SOHO EIT Geant4 Induced X-beam line outflow: marker of target structure (~100 m surface layer) C, N, O line emanations included Geant4 Users' Workhsop, SLAC

Features of electron and photon models Validity go from 250 eV to 100 GeV Elements Z=1 to 100 Data bases: -EADL (Evaluated Atomic Data Library), -EEDL (Evaluated Electrons Data Library), -EPDL97 (Evaluated Photons Data Library) from LLNL , civility Dr. Red Cullen . An adaptation of libraries particularly arranged for use with Geant4 accessible from Geant4 dispersion source . Geant4 Users' Workhsop, SLAC

… in readiness: Processes included: Compton diffusing Photoelectric impact Rayleigh impact Pair creation Bremsstrahlung Ionization Atomic unwinding Polarized forms Auger impact Positrons New material science Geant4 Users' Workhsop, SLAC

OOAD Technology as a support to physical science Rigorous selection of OO techniques  openness to augmentation and advancement Extensive utilization of configuration examples Booch strategy Geant4 Users' Workhsop, SLAC

Calculation of aggregate cross areas where E 1 and E 2 are separately the lower and higher vitality for which information ( s 1 and s 2 ) is accessible. Mean free way for a given procedure at vitality E , with n i the nuclear thickness of the i th component adding to the material organization Geant4 Users' Workhsop, SLAC

Compton dissipating Energy dispersion of the scattered photon as indicated by Klein-Nishina recipe increased by disseminating capacities F ( q ) from EPDL97 information library. The impact of disseminating capacity gets to be distinctly critical at low energies (smothers forward dispersing) Angular appropriation of the scattered photon and the force electron additionally in view of EPDL97. Rayleigh impact Angular dissemination: F ( E , q )=[1+cos 2 ( q )]  F 2 ( q ), where F ( q ) is the vitality subordinate shape calculate got from EPDL97. Geant4 Users' Workhsop, SLAC

Gamma transformation The optional e - and e + energies examined utilizing Bethe-Heitler cross areas with Coulomb redress e - and e + accepted to have symmetric precise appropriation Energy and polar edge tested w.r.t. the approaching photon utilizing Tsai differential cross area Azimuthal point created isotropically Choice of which molecule in the match is e - or e + is made arbitrarily Photoelectric impact Subshell from which the electron is discharged chosen by the cross areas of the sub-shells. De-excitation by means of isotropic fluorescence photons; move probabilities from EADL. Geant4 Users' Workhsop, SLAC

Photons Geant4 Users' Workhsop, SLAC

Electron bremsstrahlung F ( x ) acquired from EEDL. At high energies: Continuous vitality misfortune Direction of the active electron the same as that of the approaching one; rakish conveyance of transmitted photons created by a rearranged equation in view of the Tsai cross area (anticipated that would get to be distinctly isotropic in the low-E confine) Gamma beam generation Geant4 Users' Workhsop, SLAC

Electron i onisation T he d - electron creation limit T c is utilized to isolate the consistent and discrete parts of the procedure Partial sub-shell cross areas s acquired by introduction of the assessed cross segment information in the EEDL library Interaction leaves the iota in an energized state; testing for excitation is done both for ceaseless and discrete parts of the procedure Both the vitality and the edge of emanation of the scattered electron and the d - beam are viewed as The subsequent nuclear unwinding regarded as take after on partitioned prepare Geant4 Users' Workhsop, SLAC

Electron i onisation B s is the coupling vitality of sub-shell s Continuous vitality misfortune Value of coefficient A for every component is gotten from fit to EEDL information for energies accessible in the database d - electron creation Geant4 Users' Workhsop, SLAC

Atomic unwinding EADL information used to figure the total radiative and non-radiative range of X-beams and electrons discharged Auger impact and Coster-Kronig impact a work in progress; fluorescent moves actualized Transition probabilities unequivocally included for Z=6 to 100 K, L, M, N, and some O sub-shells considered. Move probabilities for sub-shells O, P, and Q unimportant (<0.1%) and littler than the accuracy with which they are known For Z=1 to 5, a neighborhood vitality store relating to the coupling vitality B of an electron in the ionized sub-shell recreated. For O, P, and Q sub-shells a photon discharged with vitality B Geant4 Users' Workhsop, SLAC

Atomic unwinding Domain disintegration prompts to an outline open to material science augmentations Geant4 Users' Workhsop, SLAC

Geant4 Users' Workhsop, SLAC

water Photon lessening coefficient Comparison with NIST information Standard electromagnetic bundle and Low Energy expansions Fe Geant4 Users' Workhsop, SLAC

Thorax cut CT picture 6 MV photon shaft Siemens KD2 Courtesy LIP and IPOFG-CROC (Coimbra designation of the Portuguese Oncology Institute) Geant4 Users' Workhsop, SLAC

x f h n  A h n 0 q a z O C y Polarized Compton Scattering The Klein - Nishina cross segment: Where, h  0 : vitality of episode photon h  : vitality of the scattered photon  : edge between the two polarization vector s Geant4 Users' Workhsop, SLAC

e " || x e " b Q x A h n e " ^ x e O C Angular conveyance of s cattered r adiation make d out of two segments : e " || and e " ^ with r espect to AOC plane  dispersion got with the class Geant4 Users' Workhsop, SLAC

Test of the circulation: a) Low vitality b) High vitality The dissemination capacity is: the place and  = h/h 0 . Low vitality : h  o << mc 2 => h   h  o =>  =1 => a = 0 the dispersion diminishes to the Thompson appropriation => the likelihood that the two polarization vectors are opposite is zero. High vitality : little  => h   h  o => equivalent to low vitality high : it is conceivable to exhibit that b/(a+b) - >0, so for this situation the circulation have a tendency to be isotropic. Geant4 Users' Workhsop, SLAC

Results Scalar item between the two polarization vectors for three distinct energies. Upper histograms : Low polar point  Lower histograms: High polar edge  100 keV 1 MeV 10 MeV These circulations are in concurrence with the cutoff points acquired beforehand . Geant4 Users' Workhsop, SLAC

Hadron and particle forms Variety of models, contingent upon vitality extend, molecule sort and charge Positive charged hadrons Density remedy for high vitality Shell adjustment term for halfway vitality Spin subordinate term Barkas and Bloch terms Chemical impact for compound materials Nuclear halting force PIXE included Bethe-Bloch model of vitality misfortune, E > 2 MeV 5 parameterisation models, E < 2 MeV in view of Ziegler and ICRU audits 3 models of vitality misfortune vacillations Positive charged particles Effective charge demonstrate Nuclear ceasing influence Scaling: 0.01 < b < 0.05 parameterisations, Bragg top in view of Ziegler and ICRU surveys b < 0.01: Free Electron Gas Model Negative charged hadrons Model unique to Geant4 Negative charged particles: required, predicted Parameterisation of accessible trial information Quantum Harmonic Oscillator Model Geant4 Users' Workhsop, SLAC

HERMES X-R ay S pectrometer on M ercury P lanetary O rbiter PIXE from sun oriented proton occasions Geant4 Users' Workhsop, SLAC

Hadrons and particles Open to augmentation and development Physics models took care of through dynamic classes Algorithms exemplified in items Transparency of physical science, obviously presented to clients Geant4 Users' Workhsop, SLAC Interchangeable and straightforward access to informational collections

Hadron and particle low-vitality e.m. expansions Low vitality hadrons and particles models in light of Ziegler and ICRU information and parameterisations Barkas impact: models for antiprotons Geant4 Users' Workhsop, SLAC

Proton vitality misfortune in H 2 O Ziegler and ICRU parameterisations Geant4 Users' Workhsop, SLAC

fluorescence GaAs lines Fe lines Application illustrations Five propelled cases created by the LowE EM WG discharged as a major aspect of the Geant4 Toolkit (bolster prepare) X-beam telescope g - beam telescope B rachytherapy Underground material science & radiation foundation X-beam fluorescence and PIXE Full scale applications demonstrating material science rules and progressed intuitive offices, all things considered, set-ups Extensive coll