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Measurement of ATOMIC PARAMETERS AT LNHB M arie -C hristine Lépy and Y ves Ménesguen Laboratoire National Henri Be PowerPoint Presentation
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Measurement of ATOMIC PARAMETERS AT LNHB M arie -C hristine Lépy and Y ves Ménesguen Laboratoire National Henri Be

Measurement of ATOMIC PARAMETERS AT LNHB M arie -C hristine Lépy and Y ves Ménesguen Laboratoire National Henri Be

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Measurement of ATOMIC PARAMETERS AT LNHB M arie -C hristine Lépy and Y ves Ménesguen Laboratoire National Henri Be

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  1. Measurement of ATOMIC PARAMETERS AT LNHBMarie-ChristineLépyand YvesMénesguenLaboratoire National Henri Becquerel France DDEP meeting – 08/10/2012

  2. Pour insérer une image : Menu « Insertion  / Image » ou Cliquer sur l’icône de la zone image ATOMIC PARAMETERS • INTRODUCTIONINTERNATIONAL INITIATIVEATTENUATION COEFFICIENTS • FLUORESCENCE YIELDS (Ge) • PHOTON EMISSION INTENSITIES (241Am)

  3. Pour insérer une image : Menu « Insertion  / Image » ou Cliquer sur l’icône de la zone image INTRODUCTION • Use of atomic parameters in decay data • -> X-ray emission intensities • Fluorescence yields • Relative intensities • Kb/Ka, Ka2/Ka1, etc.

  4. X-RAY DATA Example : 55Fe 55Fe decays by electron capture

  5. X-RAY DATA Application Photon emissionintensities -> -> Calibration of semi-conductor detectors (X-ray spectrometry) -> Determination of photon emissionintensities -> New resultsdepend on the fluorescence yields and relative photon emissionintensities …

  6. Pour insérer une image : Menu « Insertion  / Image » ou Cliquer sur l’icône de la zone image INTERNATIONAL INITIATIVE International initiative on x-ray fundamental parameters Launched in 2008 (EXRS conference)

  7. INTERNATIONAL INITIATIVE Motivation • Parametersuseful for quantitative x-ray analysis Strongdemand of usersfrommany application fields: innovativematerials, archaeometry, environment, chemistry, etc. Tables – reliability – uncertainties ? Lackof recentexperimental values (few measurementsperformed >30 yearsago) • Improvement of experimentalfacilities Synchrotron, high resolution detectors, improvedelectronics Improvementof calculation speed

  8. INTERNATIONAL INITIATIVE Goals • Initiate new measurementstakingadvantage of technicalimprovements • Performsimilarmeasurements in different institutes to establishreliabilty and associateduncertainties of the experimental values • Performcalculation for selected cases (use calculations for interpolations) • Compare calculation to experiment • Providereliablepractical tables to users

  9. INTERNATIONAL INITIATIVE Participants and events • Active participation from : • 3 National metrologyinstitutes (LNHB-NIST-PTB) • 14 Research institutes • 10 Industrialcompanies • 4 international workshops: • 1st workshop Paris Oct. 2008  definition of expert groups • 2nd workshop Berlin May 2009  road map generation • 3rd workshop Paris Nov. 2010  project options • 4th workshop NIST July 2011  definition of new expert groups • New workshop: Berlin (Feb./Mar. 2013) • Sessions at EXRS and DXC conferences

  10. INTERNATIONAL INITIATIVE Expert groups • Prioritization of FP requirements (energies, elements, uncertainties) • Experimental facilities (needsforimprovedinstrumentation) • Theory & codes – challenges: competent use and update of software • Compilations (needfornewstrategies), dataprocessing • Definition oftechnicalterms ( NMIs: LNE, NIST and PTB ) • Establishment of a common data base accessible to the public

  11. INTERNATIONAL INITIATIVE New possibilities • Advantages of today’sfacilities • Use of monochromatic radiation (synchrotron) • Tunable (primaryenery close to the bindingenergy) • Fine beam (collimation) • Energy-dispersive detectors • Energyresolution (Ka, Kb) • Counting rates (up to 105 s-1)

  12. Pour insérer une image : Menu « Insertion  / Image » ou Cliquer sur l’icône de la zone image ATOMIC PARAMETERS • INTRODUCTIONINTERNATIONAL INITIATIVEATTENUATION COEFFICIENTS • FLUORESCENCE YIELDS (Ge) • PHOTON EMISSION INTENSITIES (241Am)

  13. ATTENUATION COEFFICIENTS Presentstatus Comparison of tables of mass attenuation coefficients FP Initiative – compilation from group 4 (P. Caussin) Cullen vs. Elam D < 1% 1% ≤ D < 2% 2% ≤ D < 5% 5% ≤ D < 10% 20% ≤ D < 50% Z 10% ≤ D < 20% 50% ≤ D < 100% D ≥ 100% Energy/keV No Data

  14. ATTENUATION COEFFICIENTS Monochromatic X-Ray sources SOLEX: Monochromatic X-ray source in the 1-20 keV energy range Vacuum chamber X-ray tube (several anticathodes) Dispersive crystal (different crystals) Monochromatic beam in a constant direction C. Bonnelle et al. Nuclear Instrum. Methods in Phys. Res. A 516, 594-601 (2004)

  15. ATTENUATION COEFFICIENTS Monochromatic X-Ray sources SOLEIL: Synchrotron E=2.75 GeV Circumference: 354 m Metrology beamline 2 beamlines “hard X-rays” 100 eV – 35 keV “XUV” 30 eV – 2 keV With dedicated monochromating optics

  16. ATTENUATION COEFFICIENTS Experimentalmethod I I 0 I=I e -µx 0 x Monochromatic radiation (E), normally incident on materialwiththickness x µ : linearattenuation coefficient (cm-1) Reference flux I0 Transmittedflux I

  17. ATTENUATION COEFFICIENTS Results Tin mass attenuation coefficients I=I0exp(-µx))=I0exp(-µ/r.rx) Major difficulties: Beam quality and stability Sample thickness: some tens of µm -> Uncertainties ? Measurement of rx : mass (microbalance) / area (surface) Sn (L edgesat 3.93, 4.16 and 4.46 keV) Cu (K edgeat 8.98 keV) Relative uncertainty < 1 %

  18. Pour insérer une image : Menu « Insertion  / Image » ou Cliquer sur l’icône de la zone image ATOMIC PARAMETERS • INTRODUCTIONINTERNATIONAL INITIATIVEATTENUATION COEFFICIENTS • FLUORESCENCE YIELDS (Ge) • PHOTON EMISSION INTENSITIES (241Am)

  19. Pour insérer une image : Menu « Insertion  / Image » ou Cliquer sur l’icône de la zone image FLUORESCENCE YIELD OF GERMANIUM • Lack of reliableatomic data • (FP initiative) • Germanium (Z=32) • Semiconductorindustry • Nanotechnologies, solarenergy • HPGeDetectors (Monte Carlo simulation)

  20. Ge FLUORESCENCE YIELD Presentstatus - Tables Tables of fluorescence yields for users Krause (1979) Bambynek (1984) Hubbell (1994) Elam (2002, seeHubbell) Ratio between ωK values proposed by Hubbell et al. (1994) and those of Bambynek (1984) See FP Initiative – compilation from group 4 (J.L. Campbell)

  21. Ge FLUORESCENCE YIELD Experimental values

  22. dN(Xi) I(Ep) a b x dx FLUORESCENCE YIELD MEASUREMENT Conventionalmethod – Reflection 1 Detector 1: Transmission to depth x 2: Interaction by photoelectriceffect in K shell 3 : Atomicrearrangement by X-ray emission (wK) 4: Exit of the X-rays from the active volume 5: Interaction in detector (full-energypeak) Target p : parent (incident energy) i : fluorescence energy (a=alpha, b=beta) µ : Linearattenuation coefficient (cm-1) tK : Linearphotoelectric absorption coefficient (cm-1) ei : Detector efficiency for energyi

  23. I(E) N(X) a a FLUORESCENCE YIELD MEASUREMENT Conventionalmethod – Reflection 2 Detector p : parent (incident energy) i : fluorescence energy (a=alpha, b=beta) Target Target Requiresaccurategeometrical arrangement Requiresaccuratemeasurement of the primary radiation characteristics (reference detector) Knowlegde of the detector efficiency (including collimation geometry) Knowledgeof the interaction cross sections

  24. I(E) a a N(X) FLUORESCENCE YIELD MEASUREMENT Conventionalmethod - Transmission p : parent (incident energy) i : fluorescence energy (a=alpha, b=beta) Target Detector Requires: Knowlegdeof the detector efficiency (including collimation geometry) Knowledge of the interaction cross sections Mass attenuation coefficients in the range 3.8 <E < 11 keV, K fluorescence yield and Kb/Ka relative X-ray emission rate for Ti, V, Fe, Co, Ni, Cu and Zn measured with a tunable monochromatic X-ray source, Y. Ménesguen,, M.-C. Lépy, Nuclear Instruments and Methods in Physics Research B 268 (2010) 2477–2486

  25. I(E) a N(X) FLUORESCENCE YIELD MEASUREMENT Escape peaksmethod HPGe detector = target 1: Transmission to depth x 2: Interaction by photoelectriceffect in K shell 3 : Atomicrearrangement by X-ray emission (wK) 4: Exit of the X-rays from the active volume Detector = target The detector records the incident radiation Full-energypeak (Ep) -> Np Escape peaks (Ep-EXKi) -> Ni For Ge: EKa : 9.88 keV EKb : 10.98 keV (Axel, BNL report 271(1952)) Does not depend on the primary radiation nor detector efficiency Requiresinteraction cross sections

  26. FLUORESCENCE YIELD MEASUREMENT Attenuation coefficients Databases • Hubbell (NIST/XCOM) • Chantler (NIST/FFAST) XCOM (direct) • Ka: 36.94 cm2.g-1 • Kb: 27.44 cm2.g-1 FFAST (interpolation) • Ka: 35.30 cm2.g-1 • Kb: 25.94 cm2.g-1 Comparison of FFAST & XCOM : The values in the FFAST dataset are calculated by different methods than the XCOM dataset and may produce different results. Disagreements in the total attenuation cross sections are generally less than 5 %, but can be larger in some cases, especially near absorption edges. Comparison with experimental data does not allow us to choose between the theoretical methods due to the scatter in the values of different experimental datasets.

  27. ESCAPE PEAKS EXPERIMENT Experimental setup • HPGe detector (thickness 4 mm – area 10 mm2) • Monochromatic X-Ray source -> normal incidence • SOLEX (LiF or Quartz monochromatingcrystal) (OS13-2) • 3.5, 3.8 and 4.0 keV (L fluorescence), 12 to 16 keV • SOLEIL (Metrologybeam line, hard X-ray branch – double Si monochromator) • 12.2, 12.5, 12.7,13.0, 13.5, 14.0 keV

  28. ESCAPE PEAKS EXPERIMENT X-Ray spectra K fluorescence yield: incident energy > 12.2 keV Full-energypeak: E=14 keV Escape peaks : E=3.02 and 4.12 keV

  29. ESCAPE PEAKS EXPERIMENT Escape peaksprocessing Peaksprocessing (peak area): COLEGRAM – Gaussianwithlefttail

  30. Ge FLUORESCENCE YIELDPresentresults FFAST: XCOM: wKa= 0.479 (15)0.483 (15) wKb=0.069 (2) 0.070 (2)

  31. Ge FLUORESCENCE YIELDSynthesis FFAST : GewK= 0.548 (16) XCOM: GewK= 0.553 (17)

  32. Ge K FLUORESCENCE YIELD Conclusion • Resultswith escape peaks : wK(Ge) 0.550 (15) • Consistent withBambynekdatabase + calculations (Chen) • L fluorescence yield : 0.016 (1) • Nextsteps Measurement of attenuation coefficients Fluorescence of a target (transmission and reflection) Comparisonwith new calculations (Univ. Libon)

  33. Pour insérer une image : Menu « Insertion  / Image » ou Cliquer sur l’icône de la zone image ATOMIC PARAMETERS • INTRODUCTIONINTERNATIONAL INITIATIVEATTENUATION COEFFICIENTS • FLUORESCENCE YIELDS (Ge) • PHOTON EMISSION INTENSITIES (241Am)

  34. PHOTON EMISSION INTENSITIES 241Am - Np L X-rays Semiconductor detectors HPGe and Si(Li) (FWHM: 115 and 130 eV at 5.9 keV) Sources 241Am (electrodeposited and wheighted drops) Spectraprocessingusing COLEGRAM 241Am XL spectrum Region XLb

  35. PHOTON EMISSION INTENSITIES 241Am - Np L X-rays Identification and quantification of 19 components ICRM2007 Measurement of 241Am L X-ray emission probabilities, M.C. Lépy, J. Plagnard, L. Ferreux, Applied Radiation and Isotopes 66 (2008) 715–721

  36. PHOTON EMISSION INTENSITIES MetallicMagneticCalorimeters Cryogenicdetector g Thermal bath ~ 20 mK T0 ~ 20 mK Metallic Absorber SQUID Amplification V B Au:Er Sensor Thermal link Pick-up coil Input coil T = 300 K Room temperature electronics Photon Energy E absorber sensor coils SQUID Temperature increase DT Magnetization change DM Voltage or current change Magnetic flux change DF DV Signal: Decay time td ~ ms Imposed by the thermal link Few counts/s … Low temperature required T0< 50 mK (FWHM atd -½) time Noise: At low temperature high energy resolution achievable Statistical fluctuations negligible

  37. PHOTON EMISSION INTENSITIES Cryogenicdetector vs Semiconductor HPGe SMX1 Normalized on the Lb1 amplitude Au-Ag absorber: DEFWHM = 37 eV @ 17.75 keV DEFWHM = 40 eV @ 60 keV • Peak amplitude/background 7 times better: • Better energy resolution • Smaller Compton background by a factor 2 HPGe: DEFWHM = 200 eV @ 17.75 keV DEFWHM = 340 eV @ 60 keV

  38. 10000 6000 Counts per channel 1000 10.3 10.8 11.3 11.8 12.3 12.8 13.3 13.8 14.3 14.8 Energy (keV) PHOTON EMISSION INTENSITIES 241Am Np L X-rays Spectrum processing La Np La1 Ll and La region ? X g ? La2 Ll ? X Ll Np Lb1,2 Au Lg1 Au Ls Np Lg1 Pb Lb1 Au La Pb Lb1 Pb Ec. Ag Unidentifiedpeakslinked to rearrangement in L3 sub-shell

  39. Pour insérer une image : Menu « Insertion  / Image » ou Cliquer sur l’icône de la zone image SUMMARY • Presentation of LNHB studiesusing radionuclides and monochromatic tunable X-ray sources: • Intensive work on atomic parameters • (International initiative on FP) Improvement of mass attenuation coefficients • Measurement of K and L fluorescence yields • Conventional work on photon emission intensities with new detectors (Cryogenic detector)

  40. Thankyou for your attention!