The TOSCA Spectrometer at ISIS: the Guide Upgrade and Beyond

Pinna, Roberto S.; Zanetti, Matteo; Rudić, Svemir; Parker, Stewart F.; Armstrong, Jeff; Waller, S.; Zacek, D.; Smith, C.; Harrison, S.; Gorini, G.; Fernandez-Alonso, Félix

doi:10.1088/1742-6596/1021/1/012029

Cited by 16 publications

(25 citation statements)

References 9 publications

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“…The vibrational dynamics of pure MAPbI 3 has already been studied extensively in a previous INS study. [15] Here, we emphasize the recent upgrade of the TOSCA spectrometer, [41][42][43][44][45], which has allowed us to explore the terahertz range with a much higher signal-to-noise ratio relative to previous work. [15] The sharp modes below 30 meV are governed by combined MA + librations and vibrations of the leadiodide framework.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Cation Dynamics and Structural Stabilization in Formamidinium Lead Iodide Perovskites

Drużbicki

Laven²,

Armstrong³

et al. 2021

Preprint

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<div>The vibrational dynamics of pure and methylammonium-doped formamidinium lead iodide perovskites</div><div>(FAPbI3) has been investigated by high-resolution neutron spectroscopy. For the ?first time, we provide an exhaustive and accurate analysis of the cation vibrations and underlying local structure around the organic moiety in these materials using ?first-principles electronic-structure</div><div>calculations validated by the neutron data. Inelastic Neutron Scattering experiments on FAPbI3</div><div>provide direct evidence of the formation of a low-temperature orientational glass, unveiling the</div><div>physico-chemical origin of phase metastability in the tetragonal structure. Further analysis of these</div><div>data provides a suitable starting point to understand and explore the stabilization of the perovskite</div><div>framework via doping with small amounts of organic cations. In particular, we ?find that hydrogen</div><div>bonds in FAPbI3 are strengthened in a synergistic manner as a result of cage deformation induced</div><div>by the dynamics of the neighbouring methylammonium cations.</div>

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Section: Resultsmentioning

confidence: 99%

“…Neutron Scattering Experiments: The INS experiments were performed on the TOSCA spectrometer, [41][42][43][44][45] operating at the ISIS Neutron and Muon Source. The measurements were performed at T = 10 K. Standard corrections were applied to the data within the Mantid software package.…”

Section: Experimental and Computational Detailsmentioning

confidence: 99%

Cation Dynamics and Structural Stabilization in Formamidinium Lead Iodide Perovskites

Drużbicki

Laven²,

Armstrong³

et al. 2021

Preprint

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“…For a neutron to be detected, it needs to be captured or absorbed, rather than just scattered. Coherent elastic scattering is often used, before the neutron detection, in order to select the energy of neutrons in a given region of interest [9,20], while incoherent inelastic scattering can be used to lower the neutron energy and increase the probability for the moderated neutrons to be absorbed. On the other hand, the capture of neutrons is needed to allow for their detection.…”

Section: Neutron Methods-general Descriptionmentioning

confidence: 99%

Neutrons for Cultural Heritage—Techniques, Sensors, and Detection

Festa

Romanelli

Senesi

et al. 2020

Sensors

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Advances in research in Cultural Heritage see increasing application of a multidisciplinary approach and the combined use of physical and chemical characterization of artefacts that can be used to define their structure and their state of conservation, also providing valuable information in selecting the most suitable microclimatic conditions for the exhibition environment. This approach provides a platform for a synergic collaboration amongst researchers, restorers, conservators, and archaeologists. Existing state-of-the-art technologies for neutron-based methods are currently being applied to the study of objects of historical and cultural interest in several neutron-beam facilities around the world. Such techniques are non-invasive and non-destructive and are, therefore, ideal to provide structural information about artefacts, such as their composition, presence of alterations due to the environmental conditions, inclusions, structure of the bulk, manufacturing techniques, and elemental composition, which provide an overall fingerprint of the object’s characteristics, thanks to the nature of the interaction of neutrons with matter. Here, we present an overview of the main neutron methods for the characterization of materials of interest in Cultural Heritage and we provide a brief introduction to the sensors and detectors that are used in this framework. We conclude with some case studies underlining the impact of these applications in different archaeological and historical contexts.

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“…Finally, the path that a neutron travels into the sensitive volume of a detector can further affect STFD. On TOSCA, squashed 3 He tubes (the nearest option to an ideal "flat" geometry) are used, however, this kind of detector is not anymore available, and it does not provide position sensitivity. Thus, we tested the effect of detector voxel choice with realistic dimensions, and also considering the 3 He tube geometry.…”

Section: Method: Uncertainties and Their Simulationmentioning

confidence: 99%

“…Indirect-geometry Time-of-Flight (ToF) broadband (-20 to 4000 cm −1 ) neutron spectrometers rely on the selection of inelastically scattered neutrons with a set neutron energy. The most efficient approach to achieve this goal, as demonstrated by 20 years of TOSCA operations [1][2][3][4][5], is by collecting neutrons via High Oriented Pyrolytic Graphite (HOPG) analysers placed at about 45 • and 135 • scattering angles, on a plane parallel to the sample axis. The analysers select the neutrons through the (0 0 2) reflection, and direct them to detectors placed as near as possible to the sample plane.…”

Section: Introductionmentioning

confidence: 99%

Crystal Analyzers for Indirect-Geometry Broadband Neutron Spectrometers: Adding Reality to Idealized Design

Zanetti

Masi

Rudić

et al. 2020

J. Synch. Investig.

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The recent trend for indirect-geometry broadband neutron spectrometers to fully exploit available neutrons at pulsed spallation sources, seeks to improve their performance via the use of large-area curved analysers, which focus neutrons in time, energy and space. Herein, we describe ongoing, joint efforts between CNR (IT) and ISIS (UK) aimed at future upgrades of TOSCA at ISIS, that are also essential for the design, and subsequent construction, of VESPA at the ESS. Such an improvement in performance arises from both a larger detector coverage using a curved geometry, as well as appropriate tuning of analyser-crystal characteristics. To achieve high resolution over the entire spectral range of 0-500 meV, timefocusing of neutrons from the sample to the detector must be achieved within tight tolerances. The effect of graphite mosaicity and its variation from crystalto-crystal across the whole analyser, as well as the impact of manufacturing tol

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The TOSCA Spectrometer at ISIS: the Guide Upgrade and Beyond

Cited by 16 publications

References 9 publications

Cation Dynamics and Structural Stabilization in Formamidinium Lead Iodide Perovskites

Cation Dynamics and Structural Stabilization in Formamidinium Lead Iodide Perovskites

Neutrons for Cultural Heritage—Techniques, Sensors, and Detection

Crystal Analyzers for Indirect-Geometry Broadband Neutron Spectrometers: Adding Reality to Idealized Design

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