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Small angle neutron scattering

Small angle neutron scattering. Students: Andisiwe Stuurman, University of Fort Hare Kwindla Nobaza, University of Johannesburg Merriam Ngulube, University of Limpopo Project Coordinator: Dr. A.I Kuklin JINR Summer student practice, 3-23 September 2011, Dubna. SANS Introduction.

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Small angle neutron scattering

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  1. Small angle neutron scattering Students: Andisiwe Stuurman, University of Fort Hare Kwindla Nobaza, University of Johannesburg Merriam Ngulube, University of Limpopo Project Coordinator: Dr. A.I Kuklin JINR Summer student practice, 3-23 September 2011, Dubna

  2. SANS Introduction • Small Angle Neutron Scattering is a method used to investigate the properties of different materials by scattered neutrons at small angles. • Nuclear fission reaction – one incident neutron hits the target and emits an average of 2.5 neutrons, energy release ~ 180 MeV. • Spallation reaction is one where extremely high energy particles (e.g. protons) hit the target made of a neutron-rich material, “breaking” a heavy nucleus into highly excited fragments

  3. Yumo-SANS Instrument(FLNP) 1. Two reflectors2. Zone of reactor with moderator3. Chopper4. First collimator5. Vacuum tube6. Second collimator7. Thermostat8. Samples table9. Goniometer10-11. Vn-standard12. Ring-wire detector13. Position-sensitive detector "Volga”14. Direct beam detector.

  4. SANS: Method of Investigation • In a SANS experiment, the wavelength of the incident beam and the scattering angle define , through the relation expressing momentum conservation in an elastic interaction: • - Q is the wave vector • - λ is the neutron wavelength • - θ is the scattering angle between the direction of the transmitted and scattered beams • The dimension of a probe is D = 2π/Q • The range of Q (scattering vector) is 0.001--1 Å-1

  5. Applications of SANS The following types of samples can be analysed using SANS, with applications across various disciplines. • Chemistry: • polymers • precipitates • surfactants • colloids • gels • Biology: - proteins - viruses - lipid aggregates - emulsificators • Materials science: • alloys • glasses • composites • porous systems • grained materials • ceramics • powders

  6. Comparison Advantages disadvantages • The advantages that SANS presents, due to the neutrons’ properties are: • Contrast variation method • Interaction with nuclei • Deep penetration • SANS is expensive. • Neutron flux is very low as compared to X-ray flux. • Interaction of neutrons with matter is weak. • Cannot be operated at small scale.

  7. Project objectives • Verifying the spherical shell-like structure of apoferritin with SANS method of investigation • Determine the parameters of the structure: • Radius of gyration • Inner and outer radii • Use of different programs (Fitter 2.1.5, Primus, Origin 8.5) in order to compare the results

  8. Determining Rg using Primus

  9. Determining Rg using Origin

  10. Determining inner and outer radii using Fitter

  11. Conclusion • From the experimental data gathered from the YuMO SANS Instrument we obtained the experimental curves; • Using Primus and Origin we determined the radius of gyration of apoferritin and compared them, obtaining similar results; • Successfully modeled the experimental plot with Fitter, thus obtaining the inner and outer radii for our sample; • Apoferritin has a spherical shell-like structure

  12. References • L.A. Feigin, D I. Svergun, Structure Analysis by X-Ray and Neutron Scattering • J.Teixiera., Introduction to SANS applied to colloidal science. • Alexander Ioffe, Neutron Sources., Vol 15.,University Munster • http://www.engr.sjsu.edu/rkwok/phys275/.ppt • http://www.ncnr.nist.gov/programs/sans/ • http://www.jinr.ru

  13. Acknowledgements • DST and NRF • We would like to thank Dr A.I Kuklin and his team from Frank Laboratory of Neutron Physics. • Also we would like to extend our gratitude to the organizers of the Summer Student Practice.(JINR, Dr Jacobs, Prof. Lekala)

  14. THANK YOU FOR YOUR KIND AUDIENCE!

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