I. OrlI. Orlićić, , . M Bogovac. M BogovacS. Zhou, S.M. TangS. Zhou, S.M. Tang

Department of Physics, University of Rijeka, CroatiaDepartment of Physics, National University of Singapore, Singapore

Motivation Theoretical vs experimental spectra Simulation of PIXE and RBS spectra for

bulk samples Simulation of elemental maps Conclusion

ProtonsDeuteronsHe Ions

SIMULATIONSIMULATION

For experianced scientists: Immense help in planning an experiment and choosing the

optimal experimental conditions - saving a lot of expensive machine time,

For beginners The Package is ideal teaching tool for undergraduate and

graduate students

Through interactive dialogs user can define all Through interactive dialogs user can define all experimental parameters such asexperimental parameters such as::

IonIon : , , s protons deuterons alphas: , , s protons deuterons alphas, ,

DetectorsDetectors: , ; , , Si Ge filter materials thickness funny filter parameters: , ; , , Si Ge filter materials thickness funny filter parameters ,,

sample sample , , thickness layers, , thickness layers composition, etc.composition, etc.

An interactive software package for a complete An interactive software package for a complete simulation ofsimulation of::

PIXE and RBS spectraPIXE and RBS spectra and and

simulation of elemental maps of simple geometrical objects simulation of elemental maps of simple geometrical objects. .

Program has also a number of utility routines to Program has also a number of utility routines to calculate parameters such ascalculate parameters such as::

photon cross sections, ionization cross sectionsphoton cross sections, ionization cross sections,, detector efficiency. detector efficiency.

???

Of the VIBALABOf the VIBALAB

To facilitate calculation all fundamental parameters :are parametrised

I , , onisation cross sections for protons deuterons He ions for K ( , . and L shell ECPSSR and compiled experimental values I . .)Orlić et al

( . . .)Mass apsorption coeficients I Orlić et al

( , )Energy loss Ziegler RUMP used

( . ) + PIXE background K Ishii simulation Poison noise

( )Escape peak and tail user defined

T : 77 he original program TTPIXAN bsed on fortran F code run ++ on UNIX machine converted to Borland C for PC

applications

Through interactive dialogs and fancy UI user can define most of the experimental parameters:

incident ions and their energy,

excitation and detection geometry (angles of incident beam, exiting angles for PIXE, RBS detectors)

detector parameters (area, thickness of Be window, Au layer, ..)

filters - thickness of standard filters (kapton, mylar, Al) as well as user defined filters; ‘magic’ or ordinary,

sample composition and thickness of any number of layers.

….

Elemental Map Simulation

Parametersdefinition Auxiliary tools

Spectrum Simulation

An example of simulated PIXE and RBS #1832 spectra for NIST thin glass sample is

given for various experimental parameters and comparred with the .experiental spectra

Filter: Al, 150 µm, Φ0.5mm

2 MeV proton, Si(Li) Det. 0°/45°

NIST #1832, thin glass film, with Si 21.8 (% ) K 11.4 Ti 8.4 Fe 9.3 Zn 2.4 Pb 9.7 Ar

2 MeV protons on thin glass sample - 5 m kapt. + 10 m Al

New and Previous Simulation

Mass Absorption CoefficientsMass Absorption Coefficients Ionisation Cross SectionsIonisation Cross Sections Detector EfficiencyDetector Efficiency

Motivation D ue to geometry of samples elemental maps

( )often missinterpreted artefacts

:For simulation one has to - ( , , Define experimental set up beam geometry

, , ,,detectors filters S ( )ample layers and objects drag and drop

: Artefacts the example of a typical aerosol ( )sample cascade impactor

: Introducing Thick Target Correction ( )Factor TTCF

Department of Physics, University of Rijeka SPIRIT - Plitvice 2010

Department of Physics, University of Rijeka SPIRIT - Plitvice 2010

Department of Physics, University of Rijeka SPIRIT - Plitvice 2010

Atmospheric particles influence visibility and the global climate

Most particles of anthropogenic origin are highly toxic - submicron size

Important to know their composition and origin - new regulations and ...

Atmospheric particles influence visibility and the global climate

Most particles of anthropogenic origin are highly toxic - submicron size

Important to know their composition and origin - new regulations and ...

Natural ComponentNatural ComponentAl-Si, NaCl,Al-Si, NaCl,Natural ComponentNatural ComponentAl-Si, NaCl,Al-Si, NaCl,

Anthropogenic Component: Anthropogenic Component: H2SO4, HCl, Pb-Br-Cl, PAH, ...H2SO4, HCl, Pb-Br-Cl, PAH, ...Anthropogenic Component: Anthropogenic Component: H2SO4, HCl, Pb-Br-Cl, PAH, ...H2SO4, HCl, Pb-Br-Cl, PAH, ...

Size mSize m0.1 2 5 10 150.1 2 5 10 15

ElectronsElectrons

50 keV50 keV

ProtonsProtons2 MeV2 MeV

10 m

Cl Si Ca

K S Ti

1

4

2

3

1

2

Department of Physics, University of Rijeka SPIRIT - Plitvice 2010

1 to 20 m

Department of Physics, University of Rijeka SPIRIT - Plitvice 2010

This is what we ACTUALLY have …

In a REAL sample … proton energy loss & photon absorption CAN NOT be neglected!!

5-10 m

200 - 500 m

Department of Physics, University of Rijeka SPIRIT - Plitvice 2010

… our way!!

Into a THIN film!!Sub - m

Particle of a typical diameter of

say

5m

will translate to a thin film with

sub-micron thickness!

Thick Target Correction Factor (TTCF)

Yield(X) Real Sample

TTCF(X) = _______________

Yield (X) Ideal Sample

The Ideal sample is of the same thickness as Real but proton energy loss & photon absorption are neglected.

0 2 4 6 8 10 120.0

0.2

0.4

0.6

0.8

1.0

Zn

Ca

Si

S

Fe

Sample thickness (m)

X-r

ay y

ield

ra

tio

Th

in/I

dea

l

RCNM - NUS, Singapore ICNMTA-98

TTCF for Simple Shapes

Cubes & Spheres

Department of Physics, University of Rijeka SPIRIT - Plitvice 2010

TTCF for Simple Shapes - Cube

0 5 10 15 20 25

0.8

1.0

1.2

1.4

1.6

1.8

AlSi

S

Fe

Sphere Diameter (m)

X-r

ay

yie

ld r

ati

o R

eal /

Id

eal

ICNMTA-98

IncidentIons

x

y

zSi(L

i) Det

ecto

r

RB S D etecto r

B S

X -R ays

Simulated Si K Yield

emerging from a spherical Al-silicate

particle

Department of Physics, University of Rijeka SPIRIT - Plitvice 2010

Inte

nsi

ty /

106

0

10

20

30

40

50

-10 -5 0 5 10

Inte

nsi

ty /

106

0

5

10

-10 -5 0 5 10

Radius (m)

Si

Al

SS

SS

D = 20 m D = 10 m D = 5 m D = 2.5 m

Al

-10 -5 0 5 10 -10 -5 0 5 10

x-ray

S shell

p

Si

Al

Si

Al

Si

Al

Environmental samples are often not as ‘ideal’ as we would like them to be!

Thickness & Shape corrections have to be performed,

If not, concentrations of light elements (Na, Mg, Al, Si, S, ..) could be underestimated/overestimated by 2 to 5 times, depending on thickness and shape of dominant particles.

Department of Physics, University of Rijeka SPIRIT - Plitvice 2010

- -Ti Al SiO2 on Si substrate

x

zy

Si Ti W

Ti

Si

W

Add module for quantitative analysis with a combined PIXE & RBS results

Refine the simulation

Develop next generation - VIBA-Lab II to achieve the inverse – calcualte 3D structure from 2D elemental maps

Use the Iterative Maximum-likelihood method and the RBS information to calculate the final spatial distribution of all elements is obtained.

An interactive software package for simulation of An interactive software package for simulation of PIXE and RBS spectra is developed. PIXE and RBS spectra is developed.

Through interactive dialogs user can define all Through interactive dialogs user can define all experimental conditions, sample composition and experimental conditions, sample composition and thickness, interactively change conditions and thickness, interactively change conditions and immediately see the effect of such change.immediately see the effect of such change.

For beginnersFor beginners - VIBALAB is an excellent teaching toolexcellent teaching tool.

For expertsFor experts - VIBALAB is a great timesavergreat timesaver - will be of immense help in planning experiments and optimizing experimental conditions.