Low-energy EM group :status and plans

Geant Low Energy EM Physics working group

19-20 January 2009CERN

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Content Working-group reorganisation

Highlights since 2007 Review

Workplan 2009 2010-2012

I – Working group reorganisation since July 2008

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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

Re-organisation

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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 )

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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/LowEnergyElectromagneticPhysicsWorki

ngGroup

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

Physics processes and models

Note

The plots shown do not contain reference data.Validation will be addressed during the second low energy talk.

1) New ion ionisation model

G4IonParametrisedLossModel: a new low-energy electromagnetic model for ions

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

On behalf of A.

Lechner

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.

2) Doppler broadening in Compton scattering

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Doppler broadening in Compton scattering

Au 50 keV

G4PenelopeCompton includes it (analytical approach)

G4LowEnergyCompton recently updated (by MGPia) to deal with

Doppler broadening (EGS database approach)

Good agreement Penelope-LowEStandard Compton includes cross section suppression, but samples

final state according to Klein-NishinaLooking for suitable validation data

Compton scattering: electrons bound and not at rest (as assumed for Klein-Nishina)

change of angular distribution, reduction of XS

interesting < 0.5 MeV

On behalf of L.

Pandola

3) New PIXE models

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New PIXE ionisation cross section models

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

On behalf of H.

Abdelaouhed

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Theoretical ECPSSR Model

for K-shell ionisation

Semi-Empirical Orlic Model

for Li-subshell ionisation

Relaxation process

X-Ray Fluorescence and/or Auger effect

Final state EADL library

PIXE generation process Incident protons

Incident alpha

Total ionisationcross section

PIXE overview

Data-Driven Modelfrom

Paul&Sacher data library for K-shell ionisation by protons

New !

New !

4) « Geant4 DNA » project

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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)

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Physics models in Geant4 DNA

e p H , He+, HeElastic

scattering

> 7.4 eVScreened

Rutherford> 7 eV

Champion

- - -

Excitation

A1B1, B1A1, Ryd A+B, Ryd C+D, diffuse

bands

7.4 eV – 10 MeV

Emfietzoglou

10 eV – 500 keVMiller Green

500 keV – 10 MeVBorn

-Effective

charge scaling from same

models as for proton

Charge Change - 1 keV – 10 MeV

Dingfelder1 keV – 10 MeV

DingfelderIonisatio

n

1b1, 3a1, 1b2, 2a1 + 1a1

12.6 eV – 30 keVBorn

100 eV – 500 keVRudd

500 keV – 10 MeVBorn

100 eV – 100 MeVRudd

• Models available for liquid water only• Models in black are analytical• Models in purple use interpolated data

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Each physics process is characterized by one or several complementary or alternative models

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

Total cross sections

Software design migration for convergence Low-energy / Standard EM

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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

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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

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Example : Photoelectric effect

Standard and migrated LowE are similar

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Eexample: Penelope Compton

Gold – 50 keV Water (compound) – 6 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)

Energy (MeV) Energy (MeV)

Software performance improvement

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Speeding-up of evaluated data based processes 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 the G4LogLogInterpolation class 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

On behalf of N.

Karakatsanis

III – Workplan

2009

2010-2012

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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

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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

Plans for 2010-2012

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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

Backup slides

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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)

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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