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Text optional: Institutsname Prof. Dr. Hans Mustermann www.fzd.de Mitglied der Leibniz-Gemeinschaft High-Speed PIXE A spatially resolved PIXE setup at.

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Presentation on theme: "Text optional: Institutsname Prof. Dr. Hans Mustermann www.fzd.de Mitglied der Leibniz-Gemeinschaft High-Speed PIXE A spatially resolved PIXE setup at."— Presentation transcript:

1 Text optional: Institutsname Prof. Dr. Hans Mustermann Mitglied der Leibniz-Gemeinschaft High-Speed PIXE A spatially resolved PIXE setup at the 6 MV Tandem accelerator Josef Buchriegler J.v. Borany, D. Hanf, F. Munnik, S. Nowak, A. Renno, O. Scharf, R. Ziegenrücker SLcam® User Workshop – 16. Jan. 2014

2 2 Outline 1. PIXE fundamentals & Motivation 2. Experimental setup 3. Data evaluation & First results 4. Prospects & Challenges

3 3 PIXE Fundamentals of PIXE: Particle Induced X-ray Emission + Particle Electrons Photon e.g. Mg Particles: charged ions (mostly protons or He-ions with 2 – 4 MeV) Ionisation cross-section σ: probability for an inner-shell ionisation Fluorescence yield ω: probability for a X-ray (or Auger-electron) emission Photons: typical energies from 1 – 30 keV (K- and L-lines)

4 4 PIXE Fundamentals of PIXE: X-Ray detection & data evaluation Detector: cooled semi-conductor crystal  Si(Li) or Ge (energy dependent efficiency) Spectrum: detected X-ray photons as a function of energy Elements in spectrum:  X-ray lines: needs model for X-ray lines (shape) and intensity ratios  Background: subtraction by using a filtering method or background-model  Pileup: caused by (almost) simultaneous detection of two photons  Si escapes: interaction of photons with the detector crystal  considering all these points  fit X-ray intensities to deduce elemental composition

5 5 PIXE Fundamentals of PIXE: classical micro-beam setup Object 50x50 μm 2 Aperture 1x1 mm 2 Lens Target plane High-energy proton beam (3 µA)  Focus beam and scan over sample  big detector as close as possible proton beam on sample: 0.5 nA  new approach: position sensitive detector Target plane High energy proton beam (<1 µA)

6 6 Motivation Why a new PIXE analysis method should be developed? Requirements defined by geologists: o fast method to find trace elements (e.g. rare earth elements) o lateral resolved informations o large throughput o big samples o for grain size determination o intergrowth analysis, etc. o to avoid: additional processing steps in mining industry (braking, milling, floating)  save energy & time Solution: novel combination of PIXE as analytical method position sensitive detector  pixel-detector poly-capillary X-ray optics fast data acquisition system established evaluation software  GeoPIXE High-Speed PIXE

7 7 Experimental setup High-Speed PIXE setup 3–4 MeV protons scanning system beam diagnostic chamber sample analysis chamber SLcam® data acquisition

8 8 Experimental setup How to get lateral & spectral resolved images?  Particle beam induces divergent X-rays in sample  Capillaries are collimating and guiding the “right” photons towards the pixels pixel detector + poly-capillary optics  SLcam©

9 9 Pixels264 x 264 = Pixels size48 x 48 µm² Framerate400 / 1000 Hz Sensitive thickness450 µm Quantum efficiency 3-10 keV 20 keV Window50 µm Be Experimental setup SLcam®: X-ray Colour Camera Ø 19 mm 1:1 optics6:1 optics Lateral resolution50 µm10 µm Picture size12 x 12 mm²1.2 x 1.2 mm² Distance to sample< 10 mm0.8 mm

10 10 Data evaluation ~5 cm SLcam Imager: real-time data analysis

11 11 Data evaluation Limits of SLcam Imager Columbite

12 12 Data evaluation GeoPIXE: established evaluation software for geological samples Quantitative evaluation: detector properties sample properties (matrix) corrections for the optics X-ray line model background model pileup correction  Deconvolution of spectra

13 13 First results Lateral resolution:  Gauss-fits at several lines  lateral resolution ~ 67 µm (Rayleigh criterion)  intensity distribution along green line Measurement of known structure: 67 µm Cu-stripes on Si-wafer distances: 200/135/67 µm

14 14 First results Trace elements: Geological sample: Cassiterite measurement time: ~45 Min. beam current: ~700 nA (3 MeV)

15 15 Prospects & Challenges  Beam alignment homogeneous illumination of samples proton yield on samples  Automation movement of samples inside analysis chamber integration of optical microscope logging of experimental parameters logging of radiation doses data management  Calibration detector efficiency influence of optics windowless operation  Data evaluation full integration of GeoPIXE:  concentration maps in real-time

16 16 Acknowledgement Johannes von Borany¹ Daniel Hanf¹ Frans Munnik¹ Axel Renno² Oliver Scharf³ Stanislaw Nowak³ René Ziegenrücker² ¹ Helmholtz-Zentrum Dresden-Rossendorf, Ion Beam Center (HZDR) ² Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF) ³ Institute for Scientific Instruments (IfG) Thank you for your Attention


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