Ex Expe perime rimenta ntal l da data a che heck k of SAN - PowerPoint PPT Presentation

Ex Expe perime rimenta ntal l da data a che heck k of SAN ANS me meas asur uremen ement Akhona Gura 1 , Puseletso Mokoena 2 , Modiehi Tshabalala 2 , Nangamso Nyangiwe 3,5 , Nametso Mongwaketsi 4,5 1.Walter Sisulu University, Chemistry Dept. Private Bag X1 Mthatha, 5117 2. University of Free State, Physics Dept, P.O Box 339, Bloemfontein, 9300 3. University of the Western Cape, Physics Dept, Bellville, 4. Stellenbosch University, Chemistry & Polymer Science Dept, Private Bag X1, Matieland, 7602 5. iThemba LABS, Materials Research Dept, P.O Box 722, Somerset West, 7129 Supervisor: Dr. A. Kuklin Co-supervisor: R.V. Erhan, PhD Joint Institute for Nuclear Research, Frank Laboratory of Neutron Physics

Outline Ou ne • Introduction (SANS) • Properties of neutrons • SANS Techniques & Applications • Principles of SANS • SANS Sources • IBR-2 Reactor • SANS equipment at JINR • Project Aim • Data Analysis and Results • Conclusion • References • Acknowledgements

Sm Small Angle e Neutron on Sc Scattering ng (SA SANS) S) Neutrons scattering is technique whereby a neutron beam is directed to a sample  and neutrons are scattered at an angle theta with respect to the incident beam. The scattered neutrons collected in the detector give the information about the  properties of the studied material. Scattering pattern is analyzed to give information about the size, shape, degree of  polydispersity and phase transition. Sample studied using SANS may be in length scale of 10 to 1000 Å.  The angles of scattering are in the range of ~ 0.2 – 5°. 

Propert perties ies of f neutrons ns The neutron was discovered by Chadwick in 1932.  It has zero charge and a mass of 1.0087 atomic mass unit.  It has a half life of 894 seconds.  The neutron usually penetrates well through matter and is useful for  investigating bulk condensed matter. It has a spin of 1/2 and a magnetic moment of -1.9132 nuclear magnetons. 

Types es of f neutrons ns Thermal neutrons (> 0.025 eV)  Fast neutrons (> 1 eV)  Slow neutrons (> 0.4 eV)  Epithermal neutrons (> 0.2 eV)  Cold neutrons ( 5x 10 -5 to 0.025 eV)  Continuum region neutrons (0.01 MeV to 25 MeV), etc 

Techni hniques ques & A Appl plica ications ions  Neutro tron techniq niques ues SANS  Reflectrometry  Neutron activation analysis  Neutron diffraction  Neutron radiography  Neutron backscattering  SANS applicati ations ns  Chemistry – Structure and interactions in colloidal solutions  – Mechanisms of molecular self-assembly in solutions, etc Materials Engineering – Investigations of c rystalline structure  – Investigations of ferrofluids, etc Polymers – Structure of micro phase for separated block polymers, etc  Biology – Organization of biomolecular complexes in solutions  – Mechanisms and pathways for protein folding, etc

Princ ncip iples les of SA SANS where The scattering intensity is defined as:  Q – wave vector I(Q)= ɸ F(Q)S(Q)  θ – scattering angle where  λ – wavelength of incident beam  I(Q) – scattering intensity  Ф – density of particles in volume  F(Q) – form factor  S(Q) – structure factor

Neutron on So Sources es Spallat lation n neutro ron n source ces  Most powerful source – ISIS facility in the United Kingdom Nucle lear ar reacto tors rs (Continuous & Pulsed)  Nuclear fission Most powerful source – High Flux Reactor at Institute Max von Laue-Paul Langevin in France There are 37 neutron sources in 21 countries ( Europe 23, North America 10,  Japan 2, Australia 1, India 1) JINR supervises the activity of the IBR-2 pulsed reacto tor (FLNP) P) 

IBR BR-2 2 Reactor or  IBR-2 reactor produce intense pulse neutron flux at the moderator surface ~10 16 n/cm 2 /s, with a power of 1850 MW in pulse IBR-2 Spectromet meters: rs:  Small angle scattering: YuMO  Diffraction: HRFD, DN-2, DN-6 (project), SKAT- EPSILON, FSD, DN-12  Reflectometry: REMUR, REFLEX,  GRAINS  Inelastic scattering: DIN-2PI, NERA-PR  Nuclear Physics: ISOMER, KOLHIDA  Neutron Activation Analysis: REGATA  Irradiation Facility

SA SANS S equipm pment ent at F FLNP (J (JINR) 1 – reflectors, 2 – reactor zone with water modulator, 3 – chopper, 4 – first collimator, 5 – neutron guide 6 – second collimator, 7 – Thermostat, 8 – sample table, 10 – Vanadium standard, 11,12 – scattering detectors, 14 – detector (direct beam)

Aim • Data Analysis (Fitter, SASFit and Origin software packages) • Interpretation of data

Apoferrit oferritin in  Ferritin is a ubiquitous intracellular protein that stores iron and releases it in a controlled fashion. The amount of ferritin stored reflects the amount of iron stored. The protein is produced by almost all living organisms, including algae, bacteria, higher plants, and animals. In humans, it acts as a buffer against iron deficiency and iron overload.*  Ferritin is a globular protein complex consisting of 24 protein subunits and is the primary intracellular iron-storage protein in both prokaryotes and eukaryotes, keeping iron in a soluble and non-toxic form. Ferritin that is not combined with iron is called apoferritin.  It consists of 24 four-helix bundles and is able to self assemble into 12 nm spherical protein with a 8 nm diameter cavity. *Iron Use and Storage in the Body: Ferritin and Molecular Representations, Rachel Casiday and Figure 1 Structure of the murine ferritin complex Regina Frey, Department of Chemistry, Washington Granier T, Langlois d'Estaintot B, Gallois B, Chevalier JM, Précigoux G, Santambrogio P, Arosio P (January 2003). University, St. Louis. "Structural description of the active sites of mouse L-chain ferritin at 1.2 A resolution". J. Biol. Inorg. Chem. 8 (1 – 2): 105 – 11.

Da Data ta Analysis ysis & R Result ults Guinier nier Plot Intensity (cm -1 ) Poro rod d Plot Q (A -1 ) B. Hammouda, "Structure Factor for Starburst Dendrimers”, J. Polym. Sci., Polym. Phys. Ed., 30, 1387-1390 (1992)

Test st Da Data Plot of test data Data parameters Rg = 198.998 ± 14.733 Chisq = 1.359 I(Q) = 4439.9 ± 146.099

Da Data Analysis ysis of f SA SANS S measurem ement ent Data parameters Rg = 47.4389 ± 18.492 Chisq = 2.3486 I(Q) = 1.38799 ± 0.417

Da Data Analysis sis using SA SASF SFit it soft ftwa ware re SASFit plot of Apoferittin data Plot of Apoferittin data Guinier plot Porod plot

Da Data Analysis ysis using Fitter soft ftwa ware Fitter plot of Apoferittin data Fitted Fitter plot of Apoferittin data LogI(Q)/nm Q)/nm gI(Q)/ LogI Guinier plot of Apoferittin data Porod plot of Apofirattin data Log (Q 2 )/A- 2 Log (Q 2 )/A- 2

2D D detector or images B A Test data treatment detector image Detector distance = (A) 18 m and (B) 15 m

2D D detector or images A B Apoferittin data treatment detector image Detector distance : (A) 18 m and (B) 15 m

Conc nclus lusion ion • Data analyzed successfully using Origin, SASFit and Fitter • It was shown how such a shape of the graph can determine the shape of the molecule. • Results showed that Apoferritin is a good molecule for calibration of SANS experiments for spherical objects • Softwares exist with good mathematical backgrounds for the reconstruction of the shape of a molecule using data collected from SANS experiments

Refer ferenc ences es King S.M., Small angle neutron scattering, ISIS Facility 1995 • Ghosh R. E, Egelhaaf S.U and Rennie A R., A computing guide for small angle scattering • experiments, Institut Max von Laue, Paul Langevin, 2012 JINR www.jinr.ru • Institute Laue-Langevin, France www.ill.fr • Software package SASfit for fitting small-angle scattering curves, Laboratory for Neutron • Scattering, Paul Scherrer Institut, PSI, Switzerland A.G.Soloviev, A.V.Stadnik, A.H.Islamov and A.I.Kuklin, ``Fitter. The package for fitting a • chosen theoretical multi-parameter function through a set of data points. Application to experimental data of the YuMO spectrometer. Version 2.1.0. Long Write-Up and User's Guide''. Communication of JINR E10-2008-2, Dubna, 2008. Wikipedia www.wiki.com •

Ackn knowl owledgem edgements ents • Summer Practice Organizing Committee • National Research Foundation (NRF) • Department of Science & Technology (DST), South Africa • FLNP • YuMO team • Dr. Aleksandr Kuklin • Raul Victor Erhan, PhD • Supervisors from our various institutions