Monte Carlo Techniques in Radiation Detection and Measurement.

Sixth Symposium on Use of Nuclear Techniques in Environmental Studies. Yarmouk University, JORDAN. 4-6 Sept. 2006.

Monte Carlo Techniques in

Radiation Detection and MeasurementSaed Dababneh

•Al-Balqa Applied University, JORDAN.•The University of Jordan, JORDAN.•Forschungszentrum Karlsruhe, GERMANY.•University of Notre Dame, USA.•Joint Institute for Nuclear Astrophysics, USA.•LLN, BELGIUM.•CERN.


Why MC … ?• Design a setup.• Optimize a setup.

– Geometry, materials, orientation, fields, electronics, acquisition, analysis …

• Save money and time.• Calibrate a setup … !• Solve chronic issues.• More through examples …


Geant4• A toolkit.• CERN.• High-energy physics … !• Low-energy nuclear, accelerator, astro,

medical, environmental …• C++.• Unix flavors, Linux, Cygwin on Windows.


Simulate what … ?• Geometry of the system (Modeling).• Materials.• Fundamental particles of interest.• Primary events.• Physics processes governing particle interactions

with materials and fields.• Storage of events and tracks.• Visualization of the detector and particle

trajectories.• Analysis of simulation data at different levels of

detail and refinement.


How ?

• Define physics, geometry, materials, particles …… etc…

• Random number generator.• Fast processors large number of

“events”.• Event primary interaction

secondaries interactiondetector response …

• Simulation vs. calculation …


A gamma spectrometer

Modeling an ORTEC GMXDetector at Al-Balqa.

Lateral view

Top view


Material definitionG4double a;G4double z;G4double density;G4String name, symbol;G4int ncomponents;G4double fractionmass;a = 14.007*g/mole;G4Element* elN = new G4Element(name="Nitrogen", symbol=" N" , z=7., a);a = 15.999*g/mole;G4Element *elO = new G4Element(name="Oxygen", symbol=" O" , z=8., a);density = 1.29*mg/cm3;G4Material * = new G4Material(name="Air ",density, ncomponents=2);Air->AddElement(elO, fractionmass=30.0*perCent);Air->AddElement(elN, fractionmass=70.0*perCent);

Air


VolumesG4double startFi = 0.0*deg;G4double endFi = 360.0*deg;G4double PbCapInR2 = 28.7/2*cm;G4double PbCapHalfh2 = 41.3/2.*cm;G4double AlCuthick =0.2*cm;G4double CuCapOutR = PbCapInR2;G4double CuCapInR = PbCapInR2-AlCuthick;G4double CuCapHalfh = PbCapHalfh2;G4Tubs *CuCap_tube = new

G4Tubs("CuCap_tube",CuCapInR,CuCapOutR,CuCapHalfh,startFi,endFi);G4LogicalVolume *CuCap_log = new

G4LogicalVolume(CuCap_tube,Cu,"CuCap_log",0,0,0);G4double Pos_x = 0.0*cm;G4double Pos_y = 0.0*cm;G4double Pos_z = 6.95*cm;G4VPhysicalVolume *CuCap_phys = new

G4PVPlacement(0,G4ThreeVector(Pos_x,Pos_y,Pos_z),CuCap_log,"CuCap", World_log,false,0);

Daughter

Mother


Physics … !#include "G4ComptonScattering.hh"#include "G4GammaConversion.hh"#include "G4PhotoElectricEffect.hh"void XriPhysicsList::ConstructEM(){theParticleIterator->reset();while( (*theParticleIterator)() ){

G4ParticleDefinition* particle = theParticleIterator->value();G4ProcessManager* pmanager = particle->GetProcessManager();G4String particleName = particle->GetParticleName();

if (particleName == "gamma") {

pmanager->AddDiscreteProcess(new G4PhotoElectricEffect());pmanager->AddDiscreteProcess(new G4ComptonScattering());

pmanager->AddDiscreteProcess(new G4GammaConversion());

etc …Other particles are included in a similar manner butwith their individual physics processes of interest


ValidationSimulation results exhibit excellentagreement when compared to real

documented and experimental data forrelative and absolute efficiencies.

Relative Efficiency:

Manufacturer50 %

Simulation 50.19 ± 1.06 %


Absolute Efficiency• The measured and simulated absolute efficiencies

at 662 keV of 137Cs are (0.6232 ± 0.0050)% and (0.6212 ± 0.0079)%, respectively.

• Relative error of 0.32%.• 137Cs is summing free.• So what aboutCorrection Factors … ?!!!

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 200 400 600 800 1000 1200 1400

Energy (keV)

Phot

opea

k Ef

ficie

ncy

(%)


Spectra … Experiment vs. simulation


Self Absorption

SelfSelf--AbsorptionAbsorption

Photon AttenuationPhoton Attenuation

Valid for parallelphoton emissionor far geometries.


Self absorption

Parallel PhotonEmission

Isotropic PhotonEmission

MoreRealistic

XCOM vs. Geant4 simulation


Self AbsorptionGeant4 vs. XCOM for Parallel Photon Emission

Butnot

realistic


Self Absorption

Al

Al

Fe

Fe

Geant4 vs. XCOM for Isotropic Photon Emission

in Close Geometry

Environmental

Samples


Self AbsorptionGeant4 vs. XCOM for Isotropic Photon Emission

in Close and Far Geometries


Geometric Correction FactorTotal Geometric Correction Factorfor Self-Absorption and Extended Source

AirSoil

PointSource

ExtendedSource

Detector

SampleContainer

No Coincidence Summing yet No Coincidence Summing yet ……!!


Geometric Correction FactorBAU GMX HPGe detector total geometric correction factor kBAU GMX HPGe detector total geometric correction factor kgg

for a soil sample of 4 cm height.for a soil sample of 4 cm height.


Simulated Efficiency CalibrationEfficiency Calibration of the BAU GMX System for

Environmental Samples


Coincidence Summing • Close geometry summing.• Complex decay schemes for neutron activated isotopes.• Nuclear Astrophysics.• Classical correction needs TOTAL efficiency.• MC Summing correction.• Simulate Monoenergetic & Full Decay Scheme.

Total Correction kT = kex ksa ks

• Summing-in• Summing-out

Environmental

Samples …?

Astrophysical Journal 647 (2006) 685.


A real classical issue is now solved

So, those classical chronic issues related to correction factors are solved by MC.

Now, why not go close to the detector and increaseefficiency without worrying for corrections?


Canberra … Design


Neutron Activation

• Neutron source: 7Li(p,n)7Be.• Kinematically collimated beam.• Optimized using MC.

Neutron energy distributionin the sample.

Monte-Carlo calculations.

Phys. Rev. C 69 (2004) 025803.


An optimized setup

BGO

Lead shield

Beam

BGOCloverTarget

Plastic scintillator

Down stream View Lateral View

Experimental Setup for Accelerators


Different modes of operation

Ignore scintillation No suppression.AnticoincidencesUse Pl. Scintillator Cosmic suppression.Use BGO Compton suppression.Coincidences (w/o cosmic suppression)Window on Clover + BGO Q-value gating.BGO window Cascade coincidences.Clover addback window Summing-in.Clover crystal window Summing-out.

Weakest resonancesever detected.


Superior Background Suppression

Physical Review C 68, 025801 (2003)


A setup for small samplesCorrection Factor using experimental data … !Method established by MC.

Nuclear Instruments and Methods in Physics ResearchA 517 (2004) 230-239


Other Applications

A Geant4 Monte Carlo Optimized Setup for Tissue Characterization Using Compton Scatter Technique.

Ongoing @ University of Jordan Medical Physics

Done @ University of Notre Dame

Different modes of operation of a segmented composite

Clover detector.


Accelerator Based Applications• Monte Carlo simulation of the 12C(3He,4He)11C experiment at the Notre Dame FN Tandem accelerator. • Monte Carlo simulation of the 19F(3He,3H)19Ne experimentwith different target configurations.Change Half Life…………!!!!!!!• Geant4 and SRIM Monte Carlo simulations of the recoilparticle transport through recoil separator at Notre Dame.Pure Design.• Gas Targets. @ ND and LLN.• Radioactive Ion Beams. @ LLN.• E-∆E detection. @LLN.


Change Half Life ….. !!!


Is that all … ??!!!

LHC


Is that all … ???


Many Thankswww.dababneh.com/yarmouk06

AcknowledgementMohammad Bqoor, Hanan Saleh, Nikolas Patronis, Franz Käppeler,Michael Heil, Rene Reifarth, Ralf Plag, Iris Dillmann, Michael Wiescher, Joachim Görres, Ed Stech, Claudio Ugalde.

Monte Carlo Techniques in Radiation Detection and Measurement.

Documents

Transcript of Monte Carlo Techniques in Radiation Detection and Measurement.