Low-energy EM group : status and plans

1. Low-energy EM group :status and plans Geant Low Energy EM Physics working group 19-20 January 2009CERN

2. Content • Working-group reorganisation • Highlights since 2007 Review • Workplan • 2009 • 2010-2012

3. I – Working group reorganisation since July 2008

4. Re-organisation • coordinator : S. Incerti (IN2P3/CENBG) • two steering-board representatives : • G. Cuttone (INFN/LNS) • G. Montarou (IN2P3/LPCC) • contains 18 members who are members of the Geant4 collaboration • ANSTO (Australia), CERN, CNSTN (Tunisia), FAMAF (Argentina), IN2P3 (France), INFN (Italy), Karolinska (Sweden), ESA (The Netherlands) • in collaboration with 18 « external » members • having their own expertise on specific items/activity • they are not yet members of the Geant4 collaboration • they will have the possibility to join the Geant4 collaboration after contribution to the low energy EM working group

5. 6 « mini » working groups • Low-energy EM processes • coordinator : S. Incerti (IN2P3/CENBG) • Debugging of existing models • coordinator : G. Santin (ESA/ESTEC) • Computing performance • coordinator : N. Karakatsanis (National Tech. Univ. of Athens) • Testing • coordinator : P. Guèye (Jefferson Lab/Hampton U.) • Validation • coordinator : P. Cirrone (INFN/LNS) • Documentation • coordinator : C. Zacharatou (Copenhagen University Hospital )

6. A new web site • accessible to users directly from Geant4 web site • based on Twiki at CERN • https://twiki.cern.ch/twiki/bin/view/Geant4/LowEnergyElectromagneticPhysicsWorkingGroup

7. II - Highlights since 2007 Review • New Physics processes and models • Ion ionisation model (ICRU’73) • Doppler broadening • PIXE ionisation cross sections • Geant4-DNA processes for microdosimetry • Software design migration for convergence Low-energy / Standard EM • Livermore photon processes • Penelope processes • Software performance

8. Physics processes and models Note The plots shown do not contain reference data. Validation will be addressed during the second low energy talk.

9. 1) New ion ionisation model

10. G4IonParametrisedLossModel: a new low-energy electromagnetic model for ions On behalf of A. Lechner • G4IonParametrisedLossModel is a new stopping power model for ions, currently under developement • Close collaboration between Low-Energy and Standard Electromagnetic group • Model is part of the Low-Energy package, but follows the Standard interfaces • Designated for use with the G4ionIonisation process • A prototype version of the model was included in the December 2008 release of Geant4 • Currently in validation phase • Allows to plug in electronic stopping power tables: in its default configuration the model utilizes ICRU 73 data • The ICRU 73 report provides stopping power tabulations for • ions with atomic numbers ranging from 3 to 18, as well as for iron ions, • covering many elemental materials and compounds relevant for various areas of application • Stopping data for ion-material combinations not included in the ICRU 73 report are computed by applying a scaling procedure

11. G4IonParametrisedLossModel: a new low-energy electromagnetic model for ions • The new approach is expected to improve accuracy of ion loss description in Geant4 • Previous models in Geant4 derive ion stopping powers by scaling proton or helium data (ICRU 49, NIST) using an effective charge approximation • First tests: For some ion-target couples, differences are observed between new and old model in the prediction of the ion range (see Bragg peak in figure below) • New model is expected to improve accuracy, where the effective charge approach is known to have deficiencies Fig.: Energy deposition as a function of depth for Ar-40 ions (135 MeV per nucleon)‏ impinging on aluminum oxide: Comparison of results derived with G4IonParametrisedLossModel (ICRU 73) and G4BraggIonModel (ICRU 49 + effective charge approach). Preliminary results.

12. 2) Doppler broadening in Compton scattering

13. On behalf of L. Pandola Doppler broadening in Compton scattering Compton scattering: electrons bound and not at rest (as assumed for Klein-Nishina)  changeof angular distribution, reduction of XS G4PenelopeCompton includes it (analytical approach) G4LowEnergyCompton recently updated (by MGPia) to deal with Doppler broadening (EGS database approach) Good agreement Penelope-LowE Standard Compton includes cross section suppression, but samples final state according to Klein-Nishina Looking for suitable validation data Au 50 keV interesting < 0.5 MeV

14. 3) New PIXE models

15. New PIXE ionisation cross section models On behalf of H. Abdelaouhed • PIXE is the standard method for quantitative elemental analysis in Ion Beam Analysis • New developments for the computation of ionisation cross sections in PIXE generation • Theoretical model for K-shell ionisation by protons • Theoretical model for K-shell ionisation by alpha particles • Semi-empirical model for Li-sub-shells ionisation

16. PIXE overview Incident protons PIXE generation process Incident alpha New ! X-Ray Fluorescence and/or Auger effect Total ionisation cross section Relaxation process Final state Semi-Empirical Orlic Model for Li-subshell ionisation Theoretical ECPSSR Model for K-shell ionisation EADL library Data-Driven Model from Paul&Sacher data library for K-shell ionisation by protons New !

17. 4)« Geant4 DNA » project

18. The Geant4-DNA project • Purpose : extend Geant4 modelling capabilities for the simulation of ionising radiation effects at the molecular level • Initiated in 2001 by P. Nieminen, Europen Space Agency/ESTEC • Applications : • Radiobiology, radiotherapy and hadrontherapy (ex. prediction of DNA strand breaks from ionising radiation) • Radioprotection for human exploration of Solar system • Not limited to biological materials (ex. Silicon)

19. Models available for liquid water only • Models in black are analytical • Models in purpleuse interpolated data Physics models in Geant4 DNA

20. Total cross sections • Each physics process is characterized by one or several complementary or alternativemodels • Each model provides : • a computation of the total cross section • a computation of the final state : kinematics, production of secondaries • A specific advanced example is available (microdosimetry) for users

21. Software design migration for convergence Low-energy / Standard EM

22. Objectives • Our objective is to build a coherent aproach of EM interactions in Geant4, in full collaboration between the Standard Electromagnetic and Low Energy Electromagnetic working groups (see EM Physics talk by Vladimir) • In particular, we foresee : • common physics lists, where the best models for low and high energies are used • a common software design • common validation plans • a coherent support of Geant4 hypernews • cross references between Standard EM and Low Energy EM web pages

23. Status • all Penelope processes have been migrated and tested • Livermore photon processes have been migrated and are being tested • all Geant4-DNA processes have been migrated and are being tested

24. Example : Photoelectric effect Standard and migrated LowE are similar

25. Eexample: Penelope Compton Gold – 50 keV Water (compound) – 6 MeV Energy (MeV) Energy (MeV) • absolute cross sections are consistent and energy spectra are unchanged • preliminary CPU performances are improved • initialization time (at the beginning of run) is reduced by 30% (handling of Physics tables) • running time is reduced of ~10% for water and of ~5% for gold (G4EmElementSelector)

26. Software performance improvement

27. Speeding-up of evaluated data based processes On behalf of N. Karakatsanis • Poor performance of Low Energy Photoelectric, Compton and Rayleigh models measured using GATE, as reported during the 2007 Hebden Bridge meeting • Step-by-step revision of G4EmDataSet and G4LogLogInterpolation classes, including checks in order to make sure that the revisions will induce negligible differences • An initial revision of the G4LogLogInterpolation class has been validated and included in the G4 version 9.2 . A gain of 6-10% (1.06 – 1.1 times) has been observed. • A gain of 45% is expected (1.45 times faster) if the logarithmic operations of theG4LogLogInterpolationclass are replaced by a load operation of pre-calculated logarithm values (validated for GATE simulations were photoelectric, compton and rayleigh processes are mainly used). • Work under progress to expand this implementation for all low energy EM processes of Geant4. • The performance, and therefore the gain, depends on the type of processes used and the frequency in which interpolation calculations are required by a simulation application. • N. Karakatsanis, G. Loudos, J. Apostolakis in collaboration with Standard EM

28. III – Workplan • 2009 • 2010-2012

29. Plans for 2009 • 1) Software design (June 2009) (+Std EM) - (Recommendation #3, R4, R5) • achieve testing of migrated Livermore photon processes (1 collaborator – FTE=0.25) • migration of Livermore electron processes (ionisation, bremmstrahlung) (1 collaborator – FTE=0.25) • 2) Software performance (June 2009) • improvement of G4LogLogInterpolation class (1 collaborator – FTE=0.25) • 3) Systematic testing (June 2009) (+Std EM) - (R1) (~10 collaborators – FTE ~ 2.0) • extend coverage (particles, energies, materials) of automated tests • 4) Build a reference data base for verification & validation (December 2009) (+Std EM) - (R1,R2,R3, R4, R18, R19, R21, R22, R24) (same number of collaborators as above) • theoretical predictions • experimental data • other Monte Carlo codes • 5) Debugging of processes (December 2009) – MANPOWER NEEDED(1 collaborator – FTE=0.10) • G4LowEnergyIonisation • G4hLowEnergyIonisation • 6) New Physics models with common design (December 2009) (+Std EM) • improvement of Penelope models (1 collaborator – FTE=0.25) • polarized photoelectric and gamma conversion, triple conversion models (space applications) (2 collaborators – FTE=0.20) • 7) Documentation (+Std EM) (December 2009) - (R1, R22, R24) (4 collaborators – FTE=0.40) • common EM web pages

30. Plans for 2010-2012 • Physics (+Std EM) – MANPOWER NEEDED(1 collaborator – FTE=0.25) • Migration of fluorescence/Auger emission • Software design (2010-2011) (+Std EM) – MANPOWER NEEDED(1 collaborator – FTE=0.25) • Redesign full data handling • Geant4-DNA (2009-2011) (+Std EM) (~4 collaborators – FTE~2.0) • new Physics models in liquid water / other biological materials • physico-chemistry processes implementation • molecular geometries (DNA) • biological damage quantification • other applications : material sciences, injectors

31. Manpower needs for low-energy EM • Manpower will be needer for : • Debugging of Physics bugs accumulated over the years in the LowE Physics processes (most urgent) • Implementation/migration of fluorescence and Auger emission following standard EM design • Redesign of data table handling

32. Backup slides

33. Re-organisation • Coordinator : S. Incerti (IN2P3/CENBG) • SB representatives : G. Cuttone (INFN/LNS), G. Montarou (IN2P3/LPCC), • 18 Members today (they are members of the Geant4 collaboration) • Haifa Ben Albelwahed (CNSTN, Tunisia) • Stephane Chauvie (INFN, Torino U., Italy) • Pablo Cirrone (INFN/LNS, Italy) • Giacomo Cuttone (INFN/LNS, Italy) • Gerardo De Paola (FAMAF, Argentina) • Francesco Di Rosa (INFN/LNS, Italy) • Ziad Francis (CNRS/IN2P3/IPHC, France) • Susanna Guatelli (ANSTO, Australia) • Sebastien Incerti (CNRS/IN2P3/CENBG, France) • Anton Lechner (CERN, Switzerland) • Francesco Longo (INFN/Trieste, Italy) • Alfonso Mantero (INFN/Genova, Italy) • Barbara Mascialino (Karolinska Institute, Sweden) • Gerard Montarou (CNRS/IN2P3/LPC Clermont, France) • Jakub Moscicki (CERN, Switzerland) • Luciano Pandola (INFN/LNGS, GNO, Italy) • Giorgio Russo (INFN/LNS, Italy) • Giovanni Santin (ESA/ESTEC, The Netherlands)

34. External « experts » • collaborators with their own expertise • they are not yet members of the Geant4 collaboration • they will have the possibility to join the Geant4 collaboration after one year of contribution to the low energy EM working group