The Chalk River Single Crystal Neutron Spectrometer

Hurst, D. G.; Pressesky, A. J.; Tunnicliffe, P. R.

doi:10.1063/1.1745695

Cited by 20 publications

(11 citation statements)

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“…The Chalk River approach to the production of monochromatic neutrons for use in measuring "nuclear energy levels, absorption and scattering cross-sections, nuclear reactions and the structure of matter" [2] made use of the single-crystal spectrometer [4], as shown in Figure 2. The monochromator set-up, for that is what is described, is "large and strong to carry the massive shielding required for adequate reduction of background intensity".…”

Section: The Early Period 1949-1951 21 Structure Of Fluids and Solidsmentioning

confidence: 99%

“…In order to locate the positions of the D ions for which X-ray experiments give no information, the structure [9] of ND4Cl was investigated by Goldschmidt and Hurst at 296 and 93 ± 10 K by neutron diffraction using the spectrometer described previously [4]. The second question of interest was whether the phase transition at 243 K indicated the onset of free rotation of the ammonium ions or an order-disorder transition among the ions.…”

Section: The Early Period 1949-1951 21 Structure Of Fluids and Solidsmentioning

confidence: 99%

“…The discrepancy was important, since it suggested that some essential physics was missing, and this lead eventually to the shell model. Peaks in the far-infrared absorption coefficient in Ge were readily explained as two-phonon summation bands at 77 K and three-phonon bands at 300 K. The crystal spectrometer [4] at the NRX reactor provided the incident beam of fixed wavelength, and a second spectrometer using the (111) plane of Al analyzed the scattered neutron beam. As in the previous Al experiments [19,20], the magnitude of the incident wavevector, k, was fixed, and the scattering angle and crystal angle were varied to locate the phonon frequencies near the symmetry directions around various reciprocal lattice points, τ.…”

Section: Lattice Dynamics Of Germanium Silicon and Diamondmentioning

confidence: 99%

“…Pope, which was mentioned in several places in the literature. To reach this goal, a third axis was introduced on the diffractometer to produce what Brockhouse [2,4] referred to as a crude triple-axis crystal spectrometer shown in Figure 2. The monochromating and analyzing crystals were large single crystals of aluminum grown by Henshaw, which were a major improvement on natural crystals from the perspective of resolution and intensity.…”

Section: Introductionmentioning

confidence: 99%

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The First Two Decades of Neutron Scattering at the Chalk River Laboratories

Holden

2021

QuBS

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The early advances in neutron scattering at the Chalk River Laboratories of Atomic Energy of Canada are recorded. From initial nuclear physics measurements at the National Research Experimental (NRX) reactor came the realization that, with the flux available and improvements in monochromator technology, direct measurements of the normal modes of vibrations of solids and the structure and dynamics of liquids would be feasible. With further flux increases at the National Research Universal (NRU) reactor, the development of the triple-axis crystal spectrometer, and the invention of the constant-Q technique, the fields of lattice dynamics and magnetism and their interpretation in terms of the long-range forces between atoms and exchange interactions between spins took a major step forward. Experiments were performed over a seven-year period on simple metals such as potassium, complex metals such as lead, transition metals, semiconductors, and alkali halides. These were analyzed in terms of the atomic forces and demonstrated the long-range nature of the forces. The first measurements of spin wave excitations, in magnetite and in the 3D metal alloy CoFe, also came in this period. The first numerical estimates of the superfluid fraction of liquid helium II came from extensive measurements of the phonon–roton and multiphonon parts of the inelastic scattering. After the first two decades, neutron experiments continued at Chalk River until the shut-down of the NRU reactor in 2018 and the disbanding of the neutron effort in 2019, seventy years after the first experiments.

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Section: The Early Period 1949-1951 21 Structure Of Fluids and Solidsmentioning

confidence: 99%

Section: The Early Period 1949-1951 21 Structure Of Fluids and Solidsmentioning

confidence: 99%

Section: Lattice Dynamics Of Germanium Silicon and Diamondmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The First Two Decades of Neutron Scattering at the Chalk River Laboratories

Holden

2021

QuBS

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“…Brockhouse (Brockhouse et al, 1951;Brockhouse, 1953) at Chalk River also studied scattering from thick samples using an annulus of BF 3 detectors in conjunction with the Chalk River crystal spectrometer (Hurst et al, 1950). The lowest energy resonances in cadmium and samarium were studied.…”

Section: Before Scatteringmentioning

confidence: 99%

Neutron Scattering and Capture Cross-Section Measurements

Rae¹,

Block²

1970

Experimental Neutron Resonance Spectroscopy

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Neutron Powder Diffraction

Vogt¹

2002

Characterization of Materials

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The first powder diffraction studies on simple materials such as iron metal using x rays were done independently by Debye and Scherrer (1916) in Germany and by Hull (1917) in the United States. For a long time x‐ray powder diffraction was primarily used for qualitative purposes such as phase identification and the assessment of crystallinity. The use of neutrons for such powder diffraction work has advanced significantly over the past 50 years. The continuing efforts made in unraveling the structural details of superconducting oxides and the recently discovered oxides exhibiting colossal magnetoresistance have demonstrated the indisputable usefulness of high‐resolution neutron powder diffraction. Modern powder diffraction using neutrons, x rays, and synchrotron x‐ray radiation has developed from a qualitative method some 20 years ago to a quantitative method now used to detect new phases and determine their atomic, magnetic, and mesoscopic structure as well as their volume fractions if they are present in a mixture. Neutron powder diffraction is a complementary technique to x‐ray powder diffraction and electron diffraction. The greater penetration depth of neutrons, the fact that the neutron‐nucleus interaction is a point scattering process implying no variation of the nuclear scattering length with scattering angle, the independence of the scattering cross‐section from the number of electrons ( Z ) of an element, and therefore the stronger interaction of neutrons with “light” elements such as oxygen and hydrogen, and its isotope specificity as well as its interaction with unpaired electrons (“magnetic scattering”) make neutrons a unique and indispensable probe for structural condensed matter physics and chemistry. However, x‐ray powder diffraction and, in particular, synchrotron x‐ray powder diffraction can investigate samples many thousand times smaller and have an intrinsic resolution at least one order of magnitude better than the best neutron powder diffractometer. A major drawback for neutron scattering is that it can presently only be done at large facilities (research reactors and spallation sources), whereas laboratory‐based x‐ray scattering equipment provides the same flux much more conveniently. Current governmental policies will not permit the construction or upgrade of present‐day research reactor sources in the United States. The future of U.S. neutron scattering therefore relies solely on accelerator‐based spallation sources. Electron diffraction is a very powerful tool to obtain both real and reciprocal space images of minute amounts of powders. In combination with other supplementary techniques such as solid‐state nuclear magnetic resonance (NMR), which allows, e.g., the determination of Wyckoff multiplicities and interatomic distances by exploiting the nuclear Overhauser effect (NOE), physicists, chemists, and materials scientists have a powerful arsenal to elucidate condensed matter structures.

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The Chalk River Single Crystal Neutron Spectrometer

Cited by 20 publications

References 11 publications

The First Two Decades of Neutron Scattering at the Chalk River Laboratories

The First Two Decades of Neutron Scattering at the Chalk River Laboratories

Neutron Scattering and Capture Cross-Section Measurements

Neutron Powder Diffraction

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