The J.Stefan Institute home page is located at http://ijs.muzej.si/
The F-2 home page is located at http://rubin.ijs.muzej.si/

Microanalytical Center

Particle Induced X-ray emission (PIXE)

Particle Induced gamma-ray emission (PIGE)

Nuclear Reaction Analysis (NRA)

Rutherford Backscattering Spectrometry (RBS)

Forward Scattering Spectrometry (FSS)

Elastic Recoil Detection Analysis (ERDA)

Auger Electron Spectrometry (AES)

High Resolution X-ray Spectrometry (HRXS)

Tandetron: The new 2MV tandem accelerator installed with the financial aid from IAEA and Ministry for Science and Technology.

Tandetron: In-air IBA beamline.

Research staff from the right to the left:

Milos Budnar

Zdravko Rupnik

Matjaz Zitnik

Ziga Smit

Benjamin Zorko

Franz Gasser

Primoz Pelicon

Matjaz Kavcic

Artur Mühleisen

Marjan Ravnikar

CONTACTS:

For collaboration or further information contact Milos Budnar

MAIN RESEARCH FACILITIES

HVEE TANDETRON accelerator with 2MV terminal voltage, duoplasmatron and sputtering ion sources, switching magnet with five ports for beamlines, two beamlines installed:

PIXE/PIGE/NRA beamline
in air IBA beamline

1.5MV Van de Graaff accelerator (located at J. Stefan Institute main site)

RESEARCH ACTIVITIES

Basic research in atomic physics

atomic single and multiple ionisation by charged particles
post-collision interaction (PCI)
hypersatellites in gaseous targets
second order radiative effects in X-ray spectra
models of inner shell ionisation and decay after charged particle or photon impact

Education

PIXE excercise for physics students
experimental atomic physics and interdisciplinary subjects for M.Sc. and Ph.D. degrees
public information about the safe use of low-energy accelerators for research and industry
specialisation programs for researchers from industry
international training courses

Interdisciplinary research

studies of aerosols from urbane environment
occupational health studies of aerosols from working environment
determination of hydrogen concentration profiles in material surfaces
depth profile determination of tool hard coatings
thin film analysis
usewear studies of prehistoric tools
elemental contents in antic metal alloys

DEVELOPMENT OF

accelerator-based spectroscopic methods (IBA methods)

electron spectroscopies

high-resolution X-ray spectroscopy

vacuum systems for beam transport and measurements

data acquisition and processing hardware and software

INTERNATIONAL COLLABORATION

Johannes Kepler University, Linz, Austria

University of Fribourg, Fribourg, Swiss

ATOMKI, Debrecen, Hungary

University of Rome III, Rome, Italy

ELETTRA, Trieste, Italy

University of Singapore, Singapore

University of North Texas, Denton, USA

University of Oxford, Oxford, Great Britain

University Pierre and Marie Curie, Paris, France Oxford, Great Britain

RESEARCH ACHIEVEMENTS IN 1996 AND 1997

Multiparticle excitations and many body decay processes in inner atomic shells are subject of numerous studies in experimental atomic physics. In order to study second and higher order atomic excitations, we have collaborated in measuring Ne and Ar photoabsorption spectra on the VUV undulator beamline at ELETTRA, Trieste. Some doubly excited states were observed for the first time. Of equal interest are X-ray transitions in single or multi-ionised atoms, where many-body decays occur in addition to dominant diagram transitions. Here, we have measured in collaboration with the University of Fribourg, and PSI, Villingen, the K-LM and K-MM processes of the radiative Auger effect (RAE) in Ar, Kr and Xe for the first time. Additionally, theoretical treatment of RAE has led to realisation that it is necessary to consider the variation of the atomic potential during the decay in order to achieve a better physical model.

The new Auger electron gas spectrometer has become operational. It enables research on nonradiative atomic transitions and ionisation processes (for example, it was used for measuring hypersatellites in Ne). It is equiped with magnetic field shielded UHV chamber, electrostatic energy analyser, electron gun and VME based electronics. It is run with dedicated home developed software.

AES: Inside of the Auger electron gas spectrometer

The new tandem electrostatic accelerator (TANDETRON) has been installed and two new beamlines constructed, with the financial support from IAEA and the Slovene Ministry for Science and Technology. The accelerator facility can provide improved research possibilities for investigation in several research fields related to atomic physics: chemistry, biomedicine, new materials, environment, archaeometry and others.

We have continued with the development of new spectroscopic methods with accelerated ions (IBA methods) and X-rays. The feasibilities of the ERDA have been tested on the standard samples. We have tested their feasibility on a number of interdisciplinary fields.

RELATED DOCUMENTS

Research projects

International agreements

Publications

DESCRIPTION OF SOME IBA METHODS

Figure: Schematic presentation of different IBA methods.

Particle Induced X-ray Emission

Light projectiles (protons or He ions) with the energy of few MeV excite the atoms by knocking out electrons from their inner shells (K, L). Vacancies produced by such processes are filled with electrons from the outer shells. The available energy of the transitions is manifested in the emission of characteristic X-rays (K, L-lines). In the spectrum areas under the peaks belonging to the characteristic lines are proportional to the average elemental concentrations of different elements in the sample.

Characteristics of the PIXE method:

Protons or He ions with the energy of a few MeV are usually used as the projectiles

Ion beam with the area cross section from microm² (micro PIXE) to a few mm² and the current densities from 1 pA up to 100 nA per mm² are applied

Concentrations of the elements from C up to U can be measured simultaneously

Trace elemental concentrations below ppm can be determined in the samples

In-air analysis is often applied for studies of special samples

Use:

Trace and major element analysis

Various samples

Nuclear Reaction Analysis

Nuclear Reaction Analysis (NRA) is based on the nuclear reaction between the projectile and the target nuclei. The reaction cross section depends on the projectile energy and on the counterparts involved in the collision. If the projectile has sufficient energy to penetrate the Coulomb's barrier of the target nucleus its energy is imparted to the nucleons. An intermediate nucleus in excited state is formed which decays either by photon or particle emission. Measuring the yields of reaction products when changing the projectile incident energy the elemental concentration depth distribution can be obtained also.

Characteristics of the NRA method:

Different ions with various energies are used as the projectiles

The ion beams with the cross area of 1mm² and the current density up to 1 A/mm² are usually applied

The elemental concentration sensitivity for some elements is high due to large cross sections for particular reactions

One element concentration depth profile can be measured during the measurement time

The depth resolution of the profile in the near surface region is below 10 nm

Usually gamma rays with the energies of several MeV as well as the light particles (p,n,d,alpha) are detected

Use:

Elemental analysis, element concentration profiles

Various samples

Rutherford Backscattering Spectrometry

In the Rutherford Backscattering spectrometry (RBS) large angle scattering of the incident particles by the target nuclei is employed. At fixed detector angle the energy of the projectiles emerging from a given depth determines the mass of constituent atoms and their location. The number of counts is proportional to the atomic concentration of the element. The projectiles arriving from different depth have different kinetic energies due to the slowing down in the target. The spectrum given as the number of recorded scattered projectiles per energy interval serves for the evaluation of the elemental depth distribution.

Characteristics of the RBS method:

Protons, He or Li ions with the energy of few MeV are usually used as projectiles

Projectiles scattered by the target atoms are detected at the angle near 180 degree with respect to the incident beam direction

Typically the ion beams with the cross area of 1mm² and the current density up to 100 nA/mm² are applied

The elemental concentration sensitivity: high for Al to U (< 0.1 at.%), low for Li to Mg (< 10 at.%), insensitive for hydrogen

Depth concentration profiles of the elements heavier than the projectile are measured simultaneously

Depth resolution of the depth profile in the near surface region is 15-20 nm

Use:

Elemental concentration profiles

Thin layer analysis, hard coatings studies

Elastic Recoil Detection Analysis

Elastic Recoil Detection Analysis (ERDA) is based on recording nuclei which are knocked out by the incident projectiles. In order to detect the recoiled nuclei the target is tilted at the grazing angle with respect to the direction of the incident beam. Since the impinging projectiles are scattered in all directions an absorber attached to the detector window is used to discriminate the recoiled particles from the scattered ones. A thin foil made from Al or C, which stops the projectiles and let through the recoiled nuclei only, is used. By measuring the energies of the recoiled nuclei coming from a particular depth and counting their yields a depth profile of the element is obtained.

Characteristics of the ERDA method:

He, Li or heavier ions with the energy of few MeV are usually used as projectiles

The target tilting angle is 10 to 20 degrees with respect to the incident beam

The recoiled nuclei are detected at fixed detection angle between 10 and 40 degrees

The ion beams with the cross area of 1mm² and the current density of up to 100 nA/mm² are usually applied

Depth concentration profiles of the elements lighter than the projectile are measured simultaneously

Depth resolution of the hydrogen concentration profile in the near surface region is estimated to be from 25 to 50 nm when helium ions with the energy of 1 MeV are used

Sensitivity for hydrogen concentration determination is below 0.1 at.%

Use:

Hydrogen and light element concentration profiles in near surface region

Material studies, material surface analysis