Browsing by Author "Wood, K"
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- ItemThe ANSTO contribution to a project to provide experimental standards for SAS profile prediction(Australian Institure of Nuclear Sicence and Engineering (AINSE), 2020-11-11) Duff, AP; Kirby, N; Ryan, T; Trewhella, J; Whitten, AE; Wood, KThe program CRYSOL1, was the first method developed to rapidly calculate small-angle scattering (SAS) profiles from atomic coordinates of biomolecules. It was a major breakthrough, providing the missing link between high-resolution structures and solution SAS data. The importance of this breakthrough is evident in the fact that decades later, alternate methods continue to be published with various claims of improvement. To date, each of the alternate methods published have been validated using different data sets and models. A consensus set of high quality data would be of considerable value in benchmarking the different approaches. In order to evaluate different approaches to including the hydration layer contribution to the SAS profile, it is desirable to have data obtained using X-rays (SAXS) and neutrons (SANS), the latter in H2O and D2O, as the hydration layer contribution differs significantly for each of these measurements. To develop a consensus set of high quality data, an international project involving the efforts of 37 researchers from 11 different X-ray and 3 different neutron scattering facilities across Asia, Europe and North Ⓒ The Authors.
- ItemCarboxylic acid-directed clustering and dispersion of ZrO2 nanoparticles in organic solvents: a study by small-angle x-ray/neutron scattering and NMR(American Chemical Society, 2011-06-23) Wang, SH; Sun, YS; Chiang, AST; Hung, HF; Chen, MC; Wood, KThe stable dispersion of nanoparticles in organic solvents, essential for their practical application, is often achieved by the grafting of organic dispersants. Good dispersion is usually assumed when a transparent colloidal sol is formed. However, even in such a case, the dispersion may not be in the form of distinct nanoparticles. In this study, zirconia nanoparticles have been modified with a series of carboxylic acids so that they can be dispersed in polar protic/aprotic solvents or nonpolar organic solvents as transparent colloidal sols. The dispersed state in these solvents was characterized by SAXS and SANS. In most cases, the transparent sol consists of "soft" secondary clusters generated from the ZrO2 nanoparticles. The size and fractal structure of the dispersed clusters varied with the acid modifier. Only in the linoleic acid-modified case and with chloroform as the solvent was the ZrO2 dispersed as primary particles. However, the same modification leads to secondary clusters in other solvents, such as toluene and benzene, with similar solubility parameters. The difference in the dispersion states calls for a molecular-level interpretation. It was proposed that the grafted LOA exists as a swollen and extended brush in benzene and toluene, but as a folded and compact shell in chloroform. The proposed shell structures were then confirmed by the proximity of the chain tail with the middle section observed on 2D NOESY H-1 NMR spectra. © 2011, American Chemical Society
- ItemComplementarity of SANS,TEM and APT for the study of NbC and MnS precipitates in a direct strip cast steel(Australian Microscopy and Microanalysis Society, 2016-02-04) Dorin, T; Wood, K; Stanford, N; Taylor, A; Hodgson, PDOne of the main alloy design strategies to provide strengthening to low alloy steels is the deliberate addition of strong carbide forming elements such as Nb or Ti to form nano-precipitates with a carbide or carbo-nitride chemistry 1 . The addition of Mn is also common commercial practice to remove free sulphur from the steel. Thus, low alloy steels contain at least two chemically distinct precipitate populations, coarse manganese sulphides and fine carbo-nitrides. When steel alloys are processed by thin slab or direct strip casting (DSC), a significant decrease in the size of the sulphides is observed 2 and this is a direct consequence of the higher cooling rates experienced in these processes 3 . Since DSC is a relatively new processing technology 4 , the precise measurement of these nano-sulphides has not before been required, and very little information on this topic is available in the open literature. Small angle neutron scattering (SANS), atom probe tomography and electron microscopy have been used to investigate the MnS and Nb(C,N) precipitate populations in a low alloy steel processed by direct strip casting. Rapid cooling refined the sulphides, and both the SANS and atom probe tomography data indicate that sulphur is retained in solid solution after rapid cooling. A similar result is observed for the Nb-carbonitrides. The rapid cooling supresses precipitate formation, and only small Nb and N enriched clusters are able to form. These NbN clusters have a low volume fraction compared to the equilibrium condition in which classical Nb(C,N) precipitation is complete. Finally, we present a method to extract precipitate chemistry from the SANS data in order to validate the atom probe measurements on a statistically robust specimen volume.
- ItemDynamical coupling of intrinsically disordered proteins and their hydration water: comparison with folded soluble and membrane proteins(Cell Press, 2012-07-03) Gallat, FX; Laganowsky, A; Wood, K; Gabel, F; van Eijck, L; Wuttke, J; Moulin, M; Haertlein, M; Eisenberg, D; Colletier, JP; Zaccai, G; Weik, MHydration water is vital for various macromolecular biological activities, such as specific ligand recognition, enzyme activity, response to receptor binding, and energy transduction. Without hydration water, proteins would not fold correctly and would lack the conformational flexibility that animates their three-dimensional structures. Motions in globular, soluble proteins are thought to be governed to a certain extent by hydration-water dynamics, yet it is not known whether this relationship holds true for other protein classes in general and whether, in turn, the structural nature of a protein also influences water motions. Here, we provide insight into the coupling between hydration-water dynamics and atomic motions in intrinsically disordered proteins (IDP), a largely unexplored class of proteins that, in contrast to folded proteins, lack a well-defined three-dimensional structure. We investigated the human IDP tau, which is involved in the pathogenic processes accompanying Alzheimer disease. Combining neutron scattering and protein perdeuteration, we found similar atomic mean-square displacements over a large temperature range for the tau protein and its hydration water, indicating intimate coupling between them. This is in contrast to the behavior of folded proteins of similar molecular weight, such as the globular, soluble maltose-binding protein and the membrane protein bacteriorhodopsin, which display moderate to weak coupling, respectively. The extracted mean square displacements also reveal a greater motional flexibility of IDP compared with globular, folded proteins and more restricted water motions on the IDP surface. The results provide evidence that protein and hydration-water motions mutually affect and shape each other, and that there is a gradient of coupling across different protein classes that may play a functional role in macromolecular activity in a cellular context. © 2012, Cell Press.
- ItemThe effect of molybdenum on clustering and precipitation behaviour of strip-cast steels containing niobium(Elsevier B. V., 2019-12) Jiang, L; Marceau, RKW; Guan, B; Dorin, T; Wood, K; Hodgson, PD; Stanford, NTwo high-strength low-alloy (HSLA) steels containing Nb-carbonitrides were produced, one contained Mo and the other was Mo-free. The alloys were produced by simulated direct strip casting, and were fully bainitic in the as-cast condition. Isothermal ageing treatments were carried out to precipitate harden the alloy, and the strength was measured using a shear punch test. The dislocation density was measured with X-ray diffraction (XRD), and was found to be larger in the alloy containing Mo in all ageing conditions. Atom probe tomography (APT) showed the presence of solute clusters in the as-cast condition, and the addition of Mo increased both size and volume fraction of these clusters. The solute clusters provided significant strengthening increments of up to 112 MPa, and cluster strengthening was larger in the Mo-containing alloy. Precipitation of Nb-carbonitrides was observed after longer ageing times, which were refined by the addition of Mo. This was attributed to the higher dislocation density that increased the number of nucleation sites. Precipitate chemistry was similar for both alloys, and contrary to some literature reports, minimal Mo was observed to segregate to the precipitates. A thermodynamic rationale is presented which describes the reasons that Mo segregates to the Nb-carbide in some alloys but not in others, despite the alloy chemistries being relatively similar. © 2019 Acta Materialia Inc.
- ItemEffect of molybdenum on the precipitation in ferritic niobium-containing steels produced by strip casting(Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Jiang, L; Wood, K; Dorin, T; Marceau, RKW; Stanford, NMolybdenum (Mo) is often alloyed into the steels containing niobium (Nb), in order to enhance the formation of harder microstructures, such as bainite and acicular ferrite, and denser and finer precipitates. However, the effect of Mo on the nano-precipitates formed in the ferrite of Nb steels is still subject to debate, mostly due to its experimentally challenging nature. In addition, direct strip casting is a revolutionary casting technique that integrates casting and subsequent rolling together with rapid solidification and cooling rates, which not only simplifies the process, but also confers superior energy-saving as compared to conventional alloy thermomechanical processing. In this work, therefore, we have studied the effect of Mo on the precipitation in the ferrite of a Nb-containing micro-alloyed steel produced by strip casting using various advanced characterisation techniques. Isothermal ageing treatments were carried out at 650 ℃ up to 10,000 s to form precipitates, and the strength was measured using shear punch test. Transmission electron microscopy (TEM) observation showed that precipitates were formed along dislocations in both steels with and without Mo. Atom probe tomography (APT) analyses revealed that the addition of Mo increased both size and volume fraction of solute clusters after short ageing times, which provided a much higher cluster strengthening. Precipitation of Nb-rich carbonitrides were found after longer ageing treatments. However, no significant Mo was observed to segregate to the precipitate. Small-angle neutron scattering (SANS) results indicated that the addition of Mo reduced the average precipitate size. X-ray diffraction (XRD) results suggested. © The Authors
- ItemGuanidine hydrochloride denaturation of dopamine-induced α-synuclein oligomers: a small-angle x-ray scattering study(Wiley Online Library, 2013-06-4) Pham, CLL; Kirby, N; Wood, K; Ryan, T; Roberts, B; Sokolova, AV; Barnham, KJ; Masters, CL; Knott, RB; Cappai, R; Curtain, CC; Rekas, AAlpha-synuclein (α-syn) forms the amyloid-containing Lewy bodies found in the brain in Parkinson's disease. The neurotransmitter dopamine (DA) reacts with α-syn to form SDS-resistant soluble, non-amyloid, and melanin-containing oligomers. Their toxicity is debated, as is the nature of their structure and their relation to amyloid-forming conformers of α-syn. The small-angle X-ray scattering technique in combination with modeling by the ensemble optimization method showed that the un-reacted native protein populated three broad classes of conformer, while reaction with DA gave a restricted ensemble range suggesting that the rigid melanin molecule played an important part in their structure. We found that 6 M guanidine hydrochloride did not dissociate α-syn DA-reacted dimers and trimers, suggesting covalent linkages. The pathological significance of covalent association is that if they are non-toxic, the oligomers would act as a sink for toxic excess DA and α-syn; if toxic, their stability could enhance their toxicity. We argue it is essential, therefore, to resolve the question of whether they are toxic or not. © 2013,Wiley Periodicals, Inc.
- ItemInvestigate the effect of molybdenum on precipitation in coiled strip cast niobium steels using correlative microscopy(Australian Microscopy and Microanalysis Society, 2016-02-04) Jiang, L; Dorin, T; Marceau, RKW; Wood, K; Hodgson, P; Stanford, NSteels containing both Nb and Mo have been reported to exhibit superior strength as compared to those containing only Nb. This has been explained by the formation of harder microstructures, such as bainite and acicular ferrite, and denser and finer precipitates promoted by the addition of Mo. For further improvement of this strengthening method, a fundamental understanding of the effect of Mo on precipitation in steels is necessary. Transmission electron microscopy (TEM) is commonly used for precipitation studies and provides direct imaging of the precipitates, however it only allows local observation and it is thus non statistical by nature and makes it difficult to estimate precipitates volume fraction. On the other hand, small angle neutron scattering (SANS) can be used as a statistical technique to quantitatively study precipitation. Consequently, TEM and SANS provide complementary information and are thus powerful when used in combination. SANS measurement was used to determine the size distribution and volume fraction of particles. Meanwhile, TEM observation was performed to obtain the distribution, morphology, chemistry and size of particles on the samples investigated by SANS. In this research, the effect of Mo on precipitate formation is studied in steels processed with the recently developed direct strip casting process and subsequent coiling treatment. Direct strip casting is a revolutionary casting technique that integrates casting and subsequent rolling together with rapid solidification and cooling rates, which not only simplifies the process, but also confers superior energy-saving as compared to conventional alloy thermomechanical processing. The strip cast samples were isothermally coiled at 700 ̊C for durations up to 10000 seconds. TEM results show that interphase precipitates were formed in both alloys and the size of particles were in the range of 10 nm. Additionally, SANS was used to quantify the precipitate size and volume fraction evolution during coiling.
- ItemKinetic small angle neutron scattering to study large biomolecular complexes(Australian Institute of Nuclear Science and Engineering, 2016-11-29) Inoue, R; Wood, K; Sugiyama, MProteins are the structural building blocks that make us up but also the functional molecules that drive us. Amazing advances over the last 60 years in structural biology mean we are now determining the 3D structure of over eight thousand proteins per year. Proteins rarely function as isolated entities however, and one of the next major challenges in structural biology is to examine the structure-function relationship in larger complexes made up of several individual proteins. Small angle scattering is particularly well suited to probe the space scale of large biomolecular complexes. The protein α-Crystallin makes up around a third of the structural proteins of mammalian eye lenses as well as displaying chaperone function. Here we examine the dynamical structure of α-Crystallin complexes by following exchange between the complexes using deuteration and small angle neutron scattering [1]. The work described is a result of collaborative work between all the authors listed below.
- ItemLearning about SANS instruments and data reduction from round robin measurements on samples of polystyrene latex(Wiley Blackwell, 2013-10-01) Rennie, AR; Hellsing, MS; Wood, K; Gilbert, EP; Porcar, L; Schweins, R; Dewhurst, CD; Lindner, P; Heenan, RK; Rogers, SE; Butler, PD; Krzywon, JR; Ghosh, RE; Jackson, AJ; Malfois, MMeasurements of a well-characterized 'standard' sample can verify the performance of an instrument. Typically, small-angle neutron scattering instruments are used to investigate a wide range of samples and may often be used in a number of configurations. Appropriate 'standard' samples are useful to test different aspects of the performance of hardware as well as that of the data reduction and analysis software. Measurements on a number of instruments with different intrinsic characteristics and designs in a round robin can not only better characterize the performance for a wider range of conditions but also, perhaps more importantly, reveal the limits of the current state of the art of small-angle scattering. The exercise, followed by detailed analysis, tests the limits of current understanding as well as uncovering often forgotten assumptions, simplifications and approximations that underpin the current practice of the technique. This paper describes measurements of polystyrene latex, radius 720 angstrom, with a number of instruments. Scattering from monodisperse, uniform spherical particles is simple to calculate and displays sharp minima. Such data test the calibrations of intensity, wavelength and resolution as well as the detector response. Smoothing due to resolution, multiple scattering and polydispersity has been determined. Sources of uncertainty are often related to systematic deviations and calibrations rather than random counting errors. The study has prompted development of software to treat modest multiple scattering and to better model the instrument resolution. These measurements also allow checks of data reduction algorithms and have identified how they can be improved. The reproducibility and the reliability of instruments and the accuracy of parameters derived from the data are described. © 2013, Wiley-Blackwell.
- ItemLow-temperature inflection observed in neutron scattering measurements of proteins is due to methyl rotation: direct evidence using isotope labeling and molecular dynamics simulations(American Chemical Society, 2010-04-14) Wood, K; Tobias, DJ; Kessler, B; Gabel, F; Oesterhelt, D; Mulder, FAA; Zaccai, G; Weik, MThere is increasing interest in the contribution of methyl groups to the overall dynamics measured by neutron scattering experiments of proteins. In particular an inflection observed in atomic mean square displacements measured as a function of temperature on high resolution spectrometers (~1 μeV) was explained by the onset of methyl group rotations. By specifically labeling a non-methyl-containing side-chain in a native protein system, the purple membrane, and performing neutron scattering measurements, we here provide direct experimental evidence that the observed inflection is indeed due to methyl group rotations. Molecular dynamics simulations reproduce the experimental data, and their analysis suggests that the apparent transition is due to methyl group rotation entering the finite instrumental resolution of the spectrometer. Methyl group correlation times measured by solid state NMR in the purple membrane, taken from previous work, support the interpretation. © 2010, American Chemical Society
- ItemNatural ageing behaviour in Al-Cu alloys containing Sc and Z(Australian Nuclear Science and Technology Organisation, 2021-11-24) Jiang, L; Wood, K; Knott, RB; Sokolova, AV; Dorin, TThe 2xxx series Al-Cu alloys have been extensively used as engineering structures and components of lightweight vehicles due to their excellent strength-to-weight ratio. Recent research has demonstrated that further substantial enhancement in the strength of Al-Cu alloys could be achieved by adding Sc and Zr by forming nano-sized Al3(Sc, Zr) dispersoids. However, further development and manufacturing of these new Sc and Zr-containing Al-Cu alloys are limited by a lack of basic understanding of the effect of Al3(Sc, Zr) dispersoids on the microstructural evolution during room temperature storage after quenching from solution treatment (called natural ageing). In this work, therefore, we have studied the effect of Al3(Sc, Zr) dispersoids on natural ageing behaviour in an Al-4wt.%Cu-0.1wt.%Sc-0.1wt.%Zr alloy using small-angle neutron and x-ray scattering (SANS and SAXS). The hardness measurement shows that the presence of Al3(Sc, Zr) dispersoids significantly delays the natural ageing kinetics of Al-Cu alloys. SANS was used to quantify the size distribution of Al3(Sc, Zr) dispersoids which is ~ 25 ± 3 nm. In-situ SAXS results show that the presence of Al3(Sc, Zr) dispersoids results in a significant delay in the solute clustering formation during natural ageing. This is attributed to the suppression of the natural ageing kinetics in the Al-Cu-Sc-Zr alloys. These results were confirmed by differential scanning calorimetry (DSC) and high resolution transmission electron microscopy (TEM). The suppression mechanism is hypothesized to come from the dispersoids and Sc solute acting as vacancy sinks which slows down the diffusion of solute at room temperatures. © 2021 The Authors
- ItemPhase behaviour and aggregate structures of the surface-active ionic liquid [BMIm][AOT] in water(Elsevier B.V., 2023-12-15) Zhang, YX; Marlow, JB; Wood, K; Wang, J; Warr, GG; Li, H; Atkin, RHypothesis: The surface-active ionic liquid, 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate ([BMIm][AOT]), has a sponge-like bulk nanostructure consisting of percolating polar and apolar domains formed by the ion charge groups and alkyl chains, respectively. We hypothesise that added water will swell the polar domains and change the liquid nanostructure. Experiments: Small angle X-ray scattering (SAXS), small angle neutron scattering (SANS) and polarizing optical microscopy (POM) were used to investigate the nanostructure of [BMIm][AOT] as a function of water content. Differential scanning calorimetry (DSC) was employed to probe the thermal transitions of [BMIm][AOT]-water mixtures and the mobility of water molecules. Findings: SAXS, SANS and POM show that at lower water contents, [BMIm][AOT]-water mixtures have a sponge-like nanostructure similar to the pure SAIL, at medium water contents a lamellar phase forms, and at high water contents vesicles form. DSC results reveal that water molecules are supercooled in the lamellar phase. For the first time, results reveal a series of transitions from inverse sponge, to lamellar then to vesicles, for [BMIm][AOT] upon dilution with water. © 2023 Elsevier Inc.
- ItemPolarised neutrons for materials sciences research at the Australian Nuclear Science and Technology Organisation (ANSTO)(Australian Institute of Physics, 2014-02-04) Lee, WT; Studer, AJ; Rule, KC; Danilkin, SA; Yu, DH; Mole, RA; Kennedy, SJ; Gilbert, EP; Wood, K; Klose, F; D'Adam, TMPolarised neutron scattering has been used extensively to study magnetism in materials. Diffraction allows us to resolve the distribution and orientation of the magnetic moments down to the atomic scale. Inelastic scattering studies the magnetic excitations. The complex magnetic structure in magnetic nanoparticles is a hot topic for Small Angle Neutron Scattering (SANS). Novel magnetic thin film and multilayer are the subjects of neutron reflectometry. The technique is also increasingly being used to significantly enhance the signal-to-noise ratio in SANS measurement of hydrogen-rich materials. At ANSTO, polarised neutron option is currently available on both the SANS instrument “Quokka” (incident beam) and the reflectometer “Platypus” (incident and scattered beam). Recent technological advance of polarised Helium-3 based neutron spin-filter technique has opened up the possibility of using polarised neutrons on a wider range of instruments. In addition to enhancing the capabilities of Quokka (both incident and scattered beam for hydrogen-rich material and magnetic nanoparticle studies) and Platypus (wide-angle analysis for e.g. patterned magnetic surface structure), we are installing and testing polarised neutron equipment on the diffractometer “Wombat” and inelastic-scattering instruments “Taipan”, “Pelican” and “Sika”. This new capability will become available for experiments from July 2014. Furthermore, a new supermirror polariser is being commissioned on Pelican for polarised inelastic scattering work. In this presentation, examples illustrating the technique and use of polarised neutron scattering and the current status of installation and test on instruments will be provided.
- ItemProduction and characterisation of modularly deuterated UBE2D1-Ub conjugate by small angle neutron and X-ray scattering(Springer, 2022-10-26) Pietras, Z; Duff, AP; Morad, V; Wood, K; Jeffries, CM; Sunnerhagen, MThis structural study exploits the possibility to use modular protein deuteration to facilitate the study of ubiquitin signalling, transfer, and modification. A protein conjugation reaction is used to combine protonated E2 enzyme with deuterated ubiquitin for small angle X-ray and neutron scattering with neutron contrast variation. The combined biomolecules stay as a monodisperse system during data collection in both protonated and deuterated buffers indicating long stability of the E2–Ub conjugate. With multiphase ab initio shape restoration and rigid body modelling, we reconstructed the shape of a E2–Ub-conjugated complex of UBE2D1 linked to ubiquitin via an isopeptide bond. Solution X-ray and neutron scattering data for this E2–Ub conjugate in the absence of E3 jointly indicate an ensemble of open and backbent states, with a preference for the latter in solution. The approach of combining protonated and labelled proteins can be used for solution studies to assess localization and movement of ubiquitin and could be widely applied to modular Ub systems in general. © The Author(s) 2022. Open Access CC-BY
- ItemProtein surface and core dynamics show concerted hydration-dependent activation(Wiley-V C H Verlag GMBH, 2013-01-01) Wood, K; Gallat, FX; Otten, R; van Heel, AJ; Lethier, M; van Eijck, L; Moulin, M; Haertlein, M; Weik, M; Mulder, FAABy specifically labeling leucine/valine methyl groups and lysine side chains “inside” and “outside” dynamics of proteins on the nanosecond timescale are compared using neutron scattering (see picture). Surprisingly, both groups display similar dynamics as a function of temperature, and the buried hydrophobic core is sensitive to hydration and undergoes a dynamical transition. © 2013, Wiley-VCH Verlag GmbH & Co. KGaA
- ItemQUOKKA - 40 metre reactor based monochromatic small angle neutron scattering instrument(International Conference on Neutron Scattering, 2017-07-12) Garvey, CJ; Gilbert, EP; Mata, JP; Wood, K; Wu, CMQuokka since it entered user service in 2009, has serviced the needs of the Australia neutron scattering community, but also has provided some innovative capabilities for those international users. Here we describe the current state of the Quokka instrument, and those developments in the instrument capabilities and its sample environments. The instrument is designed to enable measurements of scattered intensity on an absolute intensity scale over three orders of magnitude of the momentum transfer (3 x 10-4 Å-1 < q< 0.7 Å-1). The instrument is able to perform polarized neutron experiments and a new high count rate detector will be commissioned on the instrument next year. While the instrument has successfully engaged those traditional users of small angle scattering, the instrument has a particularly Australian context for its further development, and a nascent community has been stimulated to widen the user base in terms of scientific area.
- ItemQUOKKA a 40 m small angle neutron scattering (SANS) instrument(Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-19) Garvey, CJ; Gilbert, EP; Mata, JP; Wood, K; Wu, CMQUOKKA is a versatile small angle neutron scattering (SANS) instrument in operation at the Australian research reactor, OPAL [1]. SANS is a powerful techniques for structural characterisation require a minimum of special preparation. As a conventional 40 m pinhole instrument operating with a neutron velocity selector the instrument1 is capable of providing a statistical and non-destructive perspective on structure over length scales from 10’s to 1000’s of Ångstrom. QUOKKA has a large flexible sample area, capable of accommodating a variety of sample environments including: standard 20 position sample changer for automated measurements on solids, liquids, pastes and powders; Couette geometry rheometer for in situ rheometry/SANS; a stopped flow device; and a differential scanning calorimeter. QUOKKA is available for general use through a biannual proposal system. © The Authors.
- ItemQuokka, the pinhole small angle neutron scattering instrument, at OPAL(Australian Institute of Nuclear Science and Engineering, 2016-11-29) Gilbert, EP; Wood, K; Garvey, CJ; Mata, JP; Wu, CMQuokka is a 40 metre small angle neutron scattering instrument installed on the cold source of the OPAL research reactor operated by ANSTO. The instrument is designed to enable measurements of scattering vectors over three orders of magnitude, from 3 x 10-4 Å-1< q < 0.7 Å-1. The instrument is able to perform polarized neutron experiments and a new high count rate detector will be commissioned on the instrument next year. In addition to the standard 20-position automatic sample changer, a wide range of sample environment equipment is available for use on the beamline, some of which are unique worldwide. A rheometer, rapid heat/quench cell, dynamic light scattering, differential scanning calorimetry and a stop-flow mixing cell are all in use. The capabilities and performance of Quokka will be presented.
- ItemQuokka, the pinhole small-angle neutron scattering instrument(Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Wood, K; Garvey, CJ; Mata, JP; Wakeham, D; Wu, CM; Gilbert, EPQuokka was the first Small Angle Neutron Scattering instrument to be in operation at the Australian research reactor, OPAL [1]. It is a 40 m pinhole instrument operating with a neutron velocity selector, an adjustable collimation system providing source-sample distances of up to 20 m and a two dimensional 1 metre square position-sensitive detector, capable of measuring neutrons scattered from the sample over a secondary flight path of up to 20 m. Also offering incident beam polarization and analysis capability as well as lens focusing optics, Quokka has been designed as a general purpose SANS instrument with a large sample area, capable of accommodating a variety of sample environments. Calibrated absolute scattering intensity measurements in a standard setup may be made over a range of wavelengths between 4 x 10-3 Å-1 and 0.7 Å-1. Here we describe Quokka’s design characteristics, performance and operation, including a high count rate detector, installed in 2018. Outputs from Quokka have been published in diverse fields such as magnetism, metallurgy, mineralogy, structural biology, polymers, food science and soft matter. We present here a selection of recent scientific highlights. © 2020 The Authors.