Browsing by Author "White, R"
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- ItemThe 1st ANSTO-AINSE Workshop on Nuclear Techniques for Cultural Heritage(Taylor & Francis Online, 2019-05-24) Salvemini, F; White, R; McIntyre, GJ; Bevitt, JJ; Cubbin, KNo abstract available.
- ItemACNS sample environment update(Australian Nuclear Science and Technology Organisation, 2021-11-25) White, R; Davidson, G; D'Adam, TM; Booth, N; Baldwin, C; Shumack, ASince the last ANSTO User Meeting the sample environment group at ACNS has supported our facility users with a range of unique developments and set ups. We have had a change in structure with the laboratory group forming and working alongside us. We will report on the progress on our ongoing projects on Direct Laser Melting (DLM) deposition system co-funded by a NSW RAAP grant. Also underway are LIEF grants with equipment for use at ACNS, one includes a rheometer for use on ACNS beam instruments. This presentation will also cover our new equipment projects funded by the NCRIS RIIP scheme. This includes new cryofurnaces, a new type of furnace, a universal testing machine and other equipment. This funding will maintain and improve our existing capabilities and increase the redundancy across the SE suite to better service competing requests. © The Authors
- ItemAustralian centre for neutron scattering: sample environment report(Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-19) Manning, AG; Wakeham, D; Davidson, G; Booth, N; Imperia, P; White, R; Lee, S; D'Adam, TMIn the past 2 years since the 2016 AANSS symposium, the sample environment group of the Australian Centre for Neutron Scattering (ACNS) has continued to facilitate neutron experiments and expand sample environment capability. This report will present the current sample environment and laboratory facilities and recent developments. We have made progress in light irradiation and spectroscopy developments; on a new temperature controlled multi-sample changer with tumbling capability; on a rotational PE Cell; and on new sample probes made from composite materials. Other improvements include new high pressure couplings for helium compressors and modifications to a dilution insert to allow larger samples and use in other cryostats extending the capability. Ongoing major projects are a new superconducting split-coil magnet dedicated to SANS and TOFPAS, two new cryostats (1.5 K to 800 K temperature range) with the aim of halving the system and sample cooling time and a new dilution fridge that will allow top-loading of samples and the ability to take much larger samples than the existing dilution insert. There have also been staffing changes with previous Sample Environment Group Leader, Paolo Imperia moving into the Operations Manager position. The new group leader, Rachel White, was recently appointed. Our Laboratory Manager, Deborah Wakeham, joined us in July 2017. © The Authors.
- ItemCultural heritage project at Australian Nuclear Science and Technology Organisation (ANSTO)(Springer Nature, 2022-01-25) Salvemini, F; White, R; Levchenko, VA; Smith, AM; Pastuovic, Z; Stopic, A; Luzin, V; Tobin, MJ; Puskar, L; Howard, DL; Davis, J; Avdeev, M; Gatenby, S; Kim, MJ; Grazzi, F; Sheedy, K; Olsen, SR; Raymond, CA; Lord, C; Richards, C; Bevitt, JJ; Popelka-Filcoff, RS; Lenehan, CE; Ives, S; Dredge, P; Yip, A; Brookhouse, MT; Austin, AGThe Australian Nuclear Science and Technology Organization (ANSTO) is the home of Australia’s most significant landmark and national infrastructure for research. ANSTO operates one of the world’s most modern nuclear research reactors, OPAL; a comprehensive suite of neutron beam instruments; the Australian Synchrotron; the Electron Microscope Facility; and the Center for Accelerator Science. Over the years, the suite of nuclear methods available across ANSTO’s campuses has been increasingly applied to study a wide range of heritage materials. Since 2015 the strategic research project on cultural heritage was initiated in order to promote access to ANSTO’s capabilities and expertise, unique in the region, by cultural institution and researchers. This chapter offers a compendium of ANSTO nuclear capabilities most frequently applied to cultural heritage research. A series of innovative, interdisciplinary, and multi-technique studies conducted in close collaboration with Australian museums, institutions, and universities is also showcased. It includes research on dating Aboriginal Australian rock art and fingerprinting the sources of ochre pigments; rediscovering the technological knowledge in the making of early coinage and ancient weapons; virtually unwrapping the content of votive mummies from ancient Egypt; and investigating and restoring the original layer of a painting that can be explored by the museum audience in a novel type of exhibition based on an immersive, interactive, and virtual environment. © 2022 Springer Nature Switzerland AG
- ItemCurrent high-pressure capabilities at ACNS and future plans(Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Maynard-Casely, HE; Booth, N; Shumack, A; Baldwin, C; White, R; Rule, KC; McIntyre, GJ; Novelli, GHigh-pressure (>1 Kbar) is a marvellous variable, which can reveal mechanical properties, structural transitions and exotic behaviours. This pairs very well with neutron scattering, where the highly penetrating nature of neutron beams is idea for accessing sample within complex sample environments. The Australian Centre for Neutron Scattering (ACNS) has developed a number of capabilities for high-pressure experiments, mainly revolving around the use of our Paris-Edinburgh press but more recently with miniature diamond-anvil cells. Some of these, such as our ability to compress radioactive samples as well as combining high-pressure and high-electric fields are unique in the world. Here we review the high pressure capabilities at ACNS, and outline some directions for capabilities and measurements.
- ItemDetermination of the crystal field levels in TmV2Al20(Australian Institute of Physics, 2017-01-31) White, R; Hutchison, WD; Iles, GN; Mole, RA; Cadogan, JM; Namiki, T; Nishimura, KRecent interest in so called caged rare earth compounds of the RM2Al20-type (R = lanthanide, M = transition metal) follow from their fascinating physical and magnetic properties at low temperatures. Recent work on PrV2Al20 and PrTi2Al20 revealed unusual phenomena, including a quadrupolar Kondo effect and superconductivity, brought about by the cubic symmetry of the Pr3+ site inducing a non-magnetic ground state in the ion. As a hole analogue of the PrV2Al20 compound, TmV2Al20 has been investigated for equivalent heavy Fermion behaviour at low temperatures. In previous work, specific heat and magnetisation data were modelled with the crystal field parameters W = 0.5 K and x = -0.6 based on the Lea, Leask and Wolf formalism. However, the experimental zero field specific heat near 0.5 K could only be matched in the modelled curves using an artificial ground state broadening. In this work inelastic neutron scattering data obtained from the PELICAN time of flight spectrometer located at the OPAL reactor, Lucas Heights has allowed further refinement of the values to W = 0.42(1) K and x = -0.63(1). In addition the CEF transitions are found to be very broad, as required for the specific heat, and suggestive of strong 4f-conduction electron coupling.
- ItemDetermination of the crystal field levels in TmV2Al20(Australian Institute of Nuclear Science and Engineering, 2016-11-29) White, R; Hutchison, WD; Iles, GN; Mole, RA; Cadogan, JM; Nishimura, KThere has been increasing interest in compounds of the RM2Al20-type (R = lanthanide, M = transition metal) in recent years due to the unique physical and magnetic properties many have been shown to display at low temperatures. Recent work carried out on PrV2Al20 and PrTi2Al20 has revealed a number of interesting phenomena, including a quadrupolar Kondo effect [1, 2] and superconductivity [3, 4] brought about by the cubic symmetry of the Pr3+ site inducing a non-magnetic ground state in the ion. As a hole analogue of the PrV2Al20 compound, TmV2Al20 has been investigated to see whether it too displays such phenomena at low temperatures. Crystal field calculations based on specific heat and magnetisation have been carried out previously [5] with parameters W = 0.5 K and x = -0.6 determined based on the Lea, Leask and Wolf formalism [6]. These results have been further refined to W = 0.42(1) K and x = -0.63(1) using inelastic neutron scattering data obtained from the PELICAN time-of-flight spectrometer located at the OPAL reactor, Lucas Heights.
- ItemDetermination of the crystal field levels in TmV2Al20(International Conference on Neutron Scattering, 2017-07-12) White, R; Hutchison, WD; Iles, GN; Mole, RA; Cadogan, JM; Namiki, T; Nishimura, K.So called caged rare earth compounds of the RM Al20-type (R = lanthanide, M = transition metal) exhibit interesting physical and magnetic properties at low temperatures. For example PrV Al20 and PrTi Al20 show a quadrupolar Kondo effect [1] and superconductivity [2] brought about by the non-magnetic ground state and the cubic symmetry of the Pr3+site. In this work the compound TmV Al20, a hole analogue of PrV Al20 has been investigated. Previous crystal field calculations based on specific heat and magnetisation [3] resulted in parameters of W = 0.5 K and x = -0.6 within the Lea, Leask and Wolf formalism [4]. However to match the experimental zero field specific heat near 0.5 K, an artificial broadening of the ground state was applied. To validate and clarify these results, we have carried out an inelastic neutron scattering experiment on the PELICAN time-of-flight spectrometer to determine the energy splitting between the crystal field levels. This has allowed a further refinement of the crystal field parameters to W = 0.42(1) K and x = -0.63(1). The very broad Lorentzian line shapes suggest strong 4f-conduction band electron coupling.
- ItemDetermination of the crystal field levels in TmV2Al20(Australian Institute of Physics, 2018-01-31) Hutchison, WD; White, R; Stewart, GA; Iles, GN; Mole, RA; Cadogan, JM; Namiki, T; Nishimura, KThe interest in compounds of the RM2Al20-type (R = lanthanide, M = transition metal) in recent years reflects the fascinating physical and magnetic properties on display at low temperatures. For example, in PrV2Al20 and PrTi2Al20 the phenomena reported include a quadrupolar Kondo effect [1] and superconductivity [2]. Central to such systems is the cubic symmetry of the Pr3+ site inducing a non-magnetic ground state in the ion. As a hole analogue of the PrV2Al20 compound, TmV2Al20 has been investigated in the hope of observing similar phenomena at low temperatures. At last year’s ‘Wagga’ we reported that we had determined the Tm3+ crystal field parameters W = 0.42(1) and x = -0.63(1) [3] (based on the Lea, Leask and Wolf formalism [4]) for TmV2Al20 using inelastic neutron scattering on PELICAN at the OPAL reactor, Lucas Heights. However, the line shapes found were extremely broad Lorentzians, indicative of a coupling of crystal field states to conduction electrons, ‘smearing out’ the energy required for transitions. Here, we report more recent developments: Tm3+ electron spin resonance results together with modelling of physical properties lead to the conclusion that there is a small local distortion away from cubic symmetry.
- ItemDevelopment of Direct Laser Melting (DLM) deposition system for in-situ use on neutron beam instruments(Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Baldwin, C; White, R; Paradowska, AM; Booth, N; Davidson, G; D’Adam, TM; Shumack, A; Darmann, FDirect Laser Melting (DLM) deposition is an additive manufacturing technique in which a high power laser is used to create a melt pool on a workpiece while a jet of metal powder is applied, resulting in localised material deposition. This technique is used in industry for additive repairs, cladding with dissimilar metals, or, in conjunction with a CNC milling machine, as a full-fledged 3D additive fabrication platform. As the prominence of this technology rises, so too does interest in characterising deposition dynamics over a vast parameter space. Neutron beam instruments offer unique capabilities for such characterisation. As part of the NSW Research Attraction and Acceleration Program, ACNS is developing world first sample environment capabilities enabling in-situ laser metal deposition, for use on KOWARI and DINGO beamline. The system will utilise a self-contained motion stage and laser cladding head which will construct a thin wall structure on a user specified substrate, utilising up to two metal powders at a time. Neutron studies of the melt pool or heat affected zone can then be performed during and after printing. This paper will present the technical specifications and capabilities of the system, which will be available to the user community in late 2021. © The authors.
- ItemEvolution with applied field of the magnetic structure of TbNiAl4(Springer Link, 2014-12-17) White, R; Hutchison, WD; Goossens, DJ; Studer, AJ; Nishimura, KNeutron powder diffraction data of TbNiAl4 has been re-examined using a representational analysis, allowing a new model of the magnetic structure to be deduced. The basis vectors obtained describe an ‘elliptical helix’ type structure in which the moments rotate in the ab-plane as one moves along the c-axis. This new model has been used to simulate the expected result of a Low Temperature Nuclear Orientation (LTNO) experiment involving 299 keV gamma-ray emission from the 160Dy daughter of aligned 160Tb nuclei. Results of the simulation along the a-axis appear to partly match currently existing experimental data, with good agreement in the magnitude of lost anisotropy. © 2014, Springer International Publishing.
- ItemMagnetic phase coexistence in DyNiAl4(Elsevier, 2019-01-01) White, R; Hutchison, WD; Avdeev, MThe magnetic structure and properties of the rare earth intermetallic DyNiAl4 have been determined. Two magnetic phase transitions have been observed at TN = 20.2(1) K and TN’ = 14.6(1) K. Analysis via neutron diffraction has revealed that these correspond to the formation of two distinct magnetic phases, a low temperature collinear antiferromagnetic phase with kC = (0, 1, 0) and a higher temperature incommensurate phase with kI = (0.1745(6), 1, 0.0313(6)). The incommensurate phase consists of a sinusoidal modulation of the magnetic moment along the a- and c-axis directions. In addition, both of these phases have been found to coexist between 14.5 K and 16.1 K. © 2018 Elsevier B.V.
- ItemMultiple magnetic phases in DyNiAl4(Australian Institute of Physics, 2017-02-02) White, R; Hutchison, WD; Avdeev, MMembers of the orthorhombic RNiAl4 series of materials are known to display variations in the character and number of ordered magnetic phases dependent on the particular rare earth ion present. In TbNiAl4 there are two ordered phases, the first being an incommensurate elliptical helix type structure [1-3] and the second, lower temperature phase being a commensurate structure with magnetic moments aligned along the a-axis. In PrNiAl4, there are also two magnetic phases with the incommensurate phase in this case consisting of a sinusoidal modulation of the magnetic moment along the easy a-axis [4]. ErNiAl4 only has an incommensurate magnetic phase, with the magnetic moments pointing along the c-axis but sinusoidal in magnitude along the perpendicular a- and b-axes [5]. The magnetic phases generally exist independently of each other for a given compound, though in TbNiAl4 the incommensurate and commensurate phases have been shown to coexist in a decreasing magnetic field [2]. New neutron diffraction data recently obtained for DyNiAl4 using the ECHIDNA High Resolution Powder Diffractometer [6] has not only confirmed two ordered magnetic phases, but that these two phases coexist in the region between the two transition points identified in the specific heat data in zero applied field [7].
- ItemNew sample environment projects and developments at the Australian Centre for Neutron Scattering(Australian Institute of Physics, 2019-02-05) White, R; Imperia, P; Booth, N; D'Adam, TM; Davidson, G; Lee, S; Manning, AG; Tobin, SSince the 2018 meeting the sample environment team at the Australian Centre for Neutron Scattering (ACNS) has progressed the design and construction of the new superconducting split-coil magnet, a fast cooling closed cycle cryostat and a new type of closed cycle dilution refrigerator. The first of the two fast cooling cryostats (compact closed cycle dry cryostats, 1.5 K to 800 K) will arrive in early 2019, with a tested sample cool down of 30 minutes. The new magnet is in the final stages of design, including a sample well for our time-of-flight spectrometer PELICAN. The new magnet will have active magnetic shielding and an asymmetric coil design to allow experiments with polarised neutrons. The expected arrival for the magnet is mid-2019. The closed cycle dilution refrigerator will have high cooling power and a very large sample space allowing a new class of experiments with neutrons at ultra-low temperature, arriving in March 2019. Also presented is the development of carbon fibre sample probes to enable faster cooling and quicker sample changes.
- Item‘One layer at a time’: unlocking novel materials and structures for neutron radiation environments through additive manufacturing(Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Allen, J; Baldwin, C; Khakbax, H; Beirne, S; Filippi, B; Innis, P; White, R; Wu, L; Cortie, DL; Rule, KC; Knott, JThe fact that neutrons can penetrate deeply makes them an excellent tool for probing the inner structures of materials, however this property also means that effective management of neutron radiation is a central challenge in nuclear engineering, neutron beam science and in the electronics industry. Neutrons also form a significant proportion of space radiation, and therefore novel, lightweight materials and structures for space radiation shielding are at the forefront of Australian and international space science development. Additive Manufacturing provides opportunities for creating novel structures with often complex geometries – and in materials not otherwise possible with traditional manufacturing techniques. We have brought together a team through the ANSTO-UOW Seed Funding Scheme to focus on the question: “Can the structures and materials made possible by additive manufacturing enable novel solutions for neutron radiation environments?” THEME 1 – Polymers for neutron shielding and collimation: particularly focusing on boron nitride/polymer composites and the possibilities these composites, coupled with 3D printing techniques, can open for neutron shielding and collimation applications – both terrestrial- and space-based THEME 2 – Low-hydrogen polymers for neutron sample environments: focusing on 3D-printable polymers for additive manufacturing low-background components for neutron sample environments THEME 3 – Metals and alloys for neutron sample environments: investigating additive manufacturing of metals – particularly aluminium – and alloys for neutron environment components. This presentation discusses the opportunities and some of the promising approaches for neutron environment additive manufacturing and novel composite materials – with specific examples and initial results from this collaborative endeavour.
- ItemReinterpretation of physical property data for TmV2Al20(Australian Institute of Physics, 2020-02-04) Hutchison, WD; Stewart, GA; White, R; Iles, GN; Cadogan, JM; Namiki, T; Nishiruma, KCompounds of the RM2Al20-type (R = rare earth, M = transition metal) are of interest for the study of fundamental low temperature physical and magnetic properties. Members of this series crystallise in the cubic CeCr2Al20 structure type with the space group 4d3̅m (#227). Given that the rare earth site (cubic4̅3m / Td site symmetry) is at the centre of a polyhedron of 16 Al ions [1], members of the series are referred to as ‘caged rare earth compounds’. The relatively large lattice parameter (typically of the order of 15 Å) results in a large separation of the rare earth nearest neighbours and leads to weak R-R exchange interactions. Consequently, the magnetic ordering temperature is suppressed, typically to less than 2 K. In some cases magnetic order has not yet been observed. Investigations of PrV2Al20 and PrTi2Al20 revealed interesting phenomena associated with the non-magnetic ground state of the cubic Pr3+ site. These included the quadrupolar Kondo effect [2] and superconductivity behaviour [3]. The compound TmV2Al20 is a hole analogue of PrV2Al20 and was subsequently investigated at low temperatures in search of similar or related phenomena. A key outcome of this later work [4] was that the high quality, single crystal, heat capacity data were interpreted in terms of a cubic crystal field (CF) interaction with just the two parameters, x and W, of the Lea, Leask and Wolf [5] formalism. However an additional arbitrary broadening of the CF ground state was necessary to better match the experimental data at low temperature. In order to improve on these CF results, we carried out inelastic neutron scattering and electron paramagnetic resonance measurements which better define x and W for Tm3+ in TmV2Al20 [6]. In this paper we show that in addition to this crystal field Hamiltonian, the single crystal magnetisation and specific heat data are better interpreted in terms of a model that involves partial Al flux substitution of an approximately 10% depleted Tm “cage” site; this interpretation allows inclusion of “rattling” contributions of caged Tm and Al ions in specific heat.