Browsing by Author "D'Adam, TM"

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    ACNS sample environment update
    (Australian Nuclear Science and Technology Organisation, 2021-11-25) White, R; Davidson, G; D'Adam, TM; Booth, N; Baldwin, C; Shumack, A
    Since 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
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    Advanced sample environment support for neutron instruments at the Bragg Institute, ANSTO
    (Australian Institute of Physics, 2016-02-04) Imperia, P; Booth, N; Lee, S; D'Adam, TM; Manning, AG
    Over the last few years a number of advancements have been made in sample environments available to scientists visiting the Neutron Beam Facility run by the Bragg institute at ANSTO (Lucas Heights). Conventional sample environment equipment allows experiments to be carried out from 35mK to 1700K, magnetic fields up to 12T and electric fields up to 10kV. These extremes are not available on all neutron instruments nor with one piece of equipment. However combinations of temperature, magnetic and electric fields are also possible. These conventional sample environments will not be covered here. This presentation will outline advances made in the gas handling, vapour delivery, differential scanning calorimetry (DSC) and spectroscopy at extreme temperatures all carried out simultaneously with neutron data collection. Some examples of the complimentary data collected are also presented. Our automated gas handling system allows gas mixing (up to 4 gases), dosing (volumetric Sievert analysis) up to 200Bar, gas flow and molecular analysis with a dedicated mass spectrometer for kinetics investigations. The Hiden Isochema system is based on their commercial IMI system with the standard reaction chamber removed and replaced by thermalised capillary lines to allow the gas delivery to a sample reactor placed within a cryostat or furnace on the sample stage of our neutron instruments. Two options are available for vapour delivery. For samples that do not outgas a static system can be used where computer controlled valves control the vapour pressure. One valve is used to lower the pressure using a turbo pump and the second one to allow the vapour from the reservoir to increase the vapour pressure. Any non-corrosive liquid can be used in this system. The second vapour system, dynamically controls the vapour and dry gas flow allowing mixing of two vapours and a dry stream of gas or the recirculation of a saturated vapour through a sample reactor The DSC system is based on A Mettler Toledo model DSC1. The furnace has been moved to allow the passage of the neutron beam and Bragg designed crucibles are used to allow scattering experiments to be carried out while DSC data are collected. Quartz and Aluminium crucibles are available and temperature range of 550C to -100C is achievable. Using Ocean Optics spectrometer equipment we have successfully carried out NIR spectroscopy down to 4K while collecting Neutron diffraction data. The use a standard NIR reflection probe and modification of the cryostat sample stick allows the probe to be introduced into the cryostat. A second spectrometer is available for UV-Vis spectroscopy and can be used in a similar method. These spectrometers are also available for use on other scattering instruments over a limited temperature range.
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    Application of linear spin wave theory to the Cr8 antiferromagnetic Heisenberg Ring
    (Australian Institute of Physics, 2017-02-01) D'Adam, TM; Mole, RA; Stride, JA
    The investigation of single molecule magnets (SMMs) has proven to be a focal point of magnetism research for over three decades, leading to the discovery of structures which may find applications in data storage, quantum information processing (QIP) and spintronics. Though molecular magnetism is not a new field, there are still many complexes to investigate and understand, including a range of chains, rings, discs and cages. Amongst the considerable number of structures, particular interest has been shown to antiferromagnetic Heisenberg rings (AFHR) such as Cr8, CsFe8 and Fe18. These structures have been investigated due to their interesting magnetic behaviours which include quantum tunnelling of the Neel vector (QTNV) and a long magnetic relaxation time below their blocking temperature TB [1]. The Cr8 homometallic AFHR is one of the most well understood structures of its type having been extensively investigated since its initial synthesis using techniques including high-field EPR, cantilever torque magnetometry [2] and INS [3]. Through application of Linear Spin Wave Theory (LSWT) using the SpinW Matlab library [4] it has been possible to calculate the dynamic structure factor of the Cr8 ring; this agrees well with both the INS data collected for this structure as well as models produced using alternate methods [3]. This demonstrates that LSWT is applicable to the Cr8 ring and we plan to use this method to analyse more complex structures which also do not exhibit long range magnetic ordering.
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    Australian 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, TM
    In 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.
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    Integration of polarised 3He infrastructure with sample environment equipment
    (Australian Institute of Physics, 2017-01-31) D'Adam, TM; Booth, N; Davidson, G; Lee, S; Manning, AG; Timperon, N; Imperia, P
    Many challenges exist when attempting to integrate polarised 3He infrastructure with neutron beam instruments. This is often due to its sensitivity to the magnetic environment and also due to the compact geometry of many beam lines. One additional consideration is the effect that Sample Environment equipment can have on the functionality of a particular polarised neutron setup. We have been able to provide incident beam polarisation with two separate magnets providing fields at the sample position of up to 2 T. In addition, full polarisation analysis is possible over a temperature range of 30 mK to 800 K. To enable this, some pieces of Sample Environment equipment must be designed specifically for use with polarised 3He and in many cases modifications are necessary to accommodate the sensitive gas. We are also in the process of procuring an 8 T shielded asymmetric magnet suitable for use with polarised 3He infrastructure.
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    New sample environment projects and developments at the Australian Centre for Neutron Scattering
    (International Conference on Neutron Scattering, 2017-07-12) Imperia, P; Booth, N; D'Adam, TM; Davidson, G; Lee, S; Manning, AG
    The sample environment team at the Australian Centre for Neutron Scattering (ACNS) has been recently awarded funding for a new superconducting split-coil magnet, a fast closed cycle cryostat and a closed cycle dilution refrigerator of the latest generation. The new magnet design is of particular interest; the brief is complicated by the request to serve two separate classes of instruments: small angle scattering and time of flight. The magnet will have low fringe field, active shield design, and specific requirements for the asymmetric field gradient to allow experiments with polarised neutrons. Low fringe field values are combined with a minimum central field of 7 Tesla, wide “clean” scattering angle and dimensional and weight constraints. The design challenges and possible solutions will be detailed, together with a time frame for delivery and commissioning. The new compact closed cycle cryostat (1.5 K to 800 K) with a small He dump, aims to halve the system and sample cooling time, generating performances comparable to that of wet type “orange” cryostats without the necessity to refill with cryogenic liquids. The closed cycle dilution refrigerator will have high cooling power and large sample space, allowing new class of experiments with neutrons at ultra-low temperature. The most recent equipment built in-house and unique to the ACNS, such as the Peltier sample changer and the thermalised sample tumblers for SANS and USANS, will also be discussed.
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    New 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, S
    Since 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.
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    New sample environment projects and developments at the Australian Centre for Neutron Scattering.
    (Australian Institute of Physics, 2018-01-30) Imperia, P; Booth, N; D'Adam, TM; Davidson, G; Lee, S; Manning, AG; Tobin, S
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    Performance test on neutron polarization analysis capability of PELICAN –time of flight cold neutron spectrometer
    (International Conference on Neutron Scattering, 2017-07-12) D'Adam, TM; Lee, WT; Mole, RA; Yu, DH
    The implementation of polarization analysis on a conventional time-of-flight spectrometer has been a major instrumental goal for some time. Here we present our recent results describing our successful test of the polarization analysis option on the PELICAN spectrometer. The compact incident neutron polarization system is an integration of a solid-state bender-type supermirror polarizer with a gradient radio frequency (RF) spin flipper. Polarization analysis is achieved by using a polarized 3He neutron spin filter that covers a span of 120 degrees. The polarization analysis system is installed inside the high vacuum sample chamber through a dedicated aluminium vacuum adaptor flange. In-situ refilling of pre-generated polarized 3He gas has been implemented. The supermirror polarizer and spin flipper have been characterized with a Heusler crystal as the analyser for neutron wavelength of 4.68 Å. 95% polarization efficiency and 92% flipping efficiency have been obtained for the polarizer and spin flipper, respectively. It was found that the Fermi chopper had no depolarization effects. Further tests with the 3He analyse ron a non-magnetic alumina sample achieved overall polarization efficiency of 82% and this gives 94% analysing power for a 3He analyser filled with 1 bar of 3He gas. The T1 lifetime of the 3He cell is about 100 hours. Nuclear-spin incoherent scattering on vanadium has been performed and the 2:1 ratio between the spin-flip and non-spin-flip signal has been observed. The energy resolution of the conventional spectrometer was maintained and approximately 80 % of the detector area is still useable. More details of the instrument performance and further improvement on polarization analysis will be presented.
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    Polarised neutrons for material science research at ANSTO
    (Australian Institute of Physics, 2018-01-31) Lee, WT; D'Adam, TM
    Polarised neutron scattering can definitively identify magnetic structures and dynamics, and separate the structural signal and the spin-incoherent scattering in hydrogen-rich materials. At ANSTO, our project to incorporate this capability to a wide suit of instruments is coming to fruition. User research experiments using polarised neutrons have recently been carried out to study multiferroic and magnetostrictive materials on the TAIPAN thermal triple-axis spectrometer and WOMBAT high-intensity diffractometer, and from an earlier time, magnetic multilayers on the PLATYPUS reflectometer. One of the first round of user research has been published. We have now also completed the deployment and test on the PELICAN cold neutron chopper spectrometer, QUOKKA SANS instrument and SIKA cold triple-axis spectrometer. Condensed matter research experiments will be carried out on those three instruments in the first half of 2018. The ECHIDNA high-resolution diffractometer is the next instrument to acquire this capability. Our development focus is now on providing user support to plan experiment, reduce data and analyse data: Rather than a surveying technique, a polarised neutron experiment is often done in the regions of interest identified using unpolarised neutron measurements. The type of polarizer and analyser (often polarised Helium-3 based) would affect what and how the measurements will be done. And polarised neutron data reduction and analysis would add a level of complexity to the process. This presentation will provide an overview of the capabilities available, some of the experiments that had been carried out to illustrate how material research can utilize polarised neutrons and the key factors to consider in planning an experiment and reducing the data.
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    Polarised 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, TM
    Polarised 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.