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Neutron Diffraction @ANSTO

Neutron Diffraction @ANSTO. Alison Edwards Bragg Institute – ANSTO. What to do when there’s a nuclear reactor next door…. Assemble the best team of scientists, engineers and tradespeople and build something to match!. www.ansto.gov.au/research/bragg_institute.html.

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Neutron Diffraction @ANSTO

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  1. Neutron Diffraction @ANSTO Alison Edwards Bragg Institute – ANSTO

  2. What to do when there’s a nuclear reactor next door… Assemble the best team of scientists, engineers and tradespeople and build something to match! www.ansto.gov.au/research/bragg_institute.html

  3. Diffraction – what is it? • Radiation interacting with matter where spacing between scattering centres is similar to the wavelength of the radiation • If we have a suitable lens we can create a direct image

  4. The Mathematics • Laue conditions “White Beam” experiment (discovery 1912, Nobel Prize 1914 Friedrich and Knipping were Laue’s students) • l = 2d sinQ (Lawrence Bragg early 20s, discovery 1913 Nobel Prize 1915) monochromatic experiment • Laue conditions stated first, but insoluble, Bragg equation is a valid solution

  5. Neutron Attenuation idea and realization: Heinz-Werner Schmitz, GKSS

  6. Neutron Diffraction instruments • WOMBAT and ECHIDNA are powder diffractometers • KOALA is a single crystal diffractometer • KOWARI uses diffraction measurements to assess stress in objects • The neutron was not discovered until 1932(Chadwick, Nobel Prize 1935)

  7. Ewald Sphere 2q Incident Beam reciprocal lattice origin q-2q scan 1/l

  8. Powder Diffraction • Many tiny crystals • Random orientations (we hope) • Inherently 1-D data • Suffers from overlap • Resolution dependent on distance from crystal • Do not need single crystals- microcrystalline powder will work well

  9. Single Crystal Diffraction • Data inherently 3-Dimensional • Problems can arise due to absorption and/or primary and seconday beam extinction • Must have single crystal of suitable size – minimum 0.1 mm3 ie 0.5 x 0.5 x 0.5 mm3

  10. A Laue Pattern • Attribution to ILL needed

  11. Ewald Sphere 2q Incident Beam reciprocal lattice origin q-2q scan 1/l

  12. Neutron scattering length and density Neutron SLD (10-6 Å-2) (H2O) = -0.56; (D2O) = 6.36

  13. Better Than X-ray Vision ?...(Neutron Radiography) Penetrating ability of neutrons - sensitive to nuclei such as boron and hydrogen

  14. Thank You

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