Pelican — a Time of Flight Cold Neutron Polarization Analysis Spectrometer at OPAL

Yu, Dehong; Mole, Richard A.; Noakes, Terry; Kennedy, S.J.; Robinson, R. A.

doi:10.7566/jpsjs.82sa.sa027

Cited by 94 publications

(80 citation statements)

References 8 publications

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“…Inelastic neutron scattering (INS) experiments were carried out on the time-of-flight cold neutron spectrometer (PELICAN) at the Bragg Institute, Australian Nuclear Science and Technology Organisation. 16,17 The K 0.55 RhO 2 powder sample was placed in an annular aluminium can. The wavelength of the neutrons was 4.74 Å with energy of 3.64 meV.…”

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confidence: 99%

Lattice dynamics of KxRhO2 single crystals

Zhang

Dong

et al. 2015

AIP Advances

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A series of crystals KxRhO2 (x = 0.72, 0.63, 0.55, 0.39, and 0.24) have been synthesized and their vibrational properties have been studied by first principles calculations, Raman spectroscopy, and inelastic neutron scattering. The measured vibrational spectra of KxRhO2 for x = 0.72 and 0.63 are consistent with the theoretical prediction for the stoichiometric KRhO2. For samples with x = 0.55, 0.39 and 0.24, extra vibrational modes have been observed and they are believed to be due to the symmetry reduction and the loss of translational symmetry induced by K disorder. The good agreement was found for the phonon density of states among the Raman spectroscopic observations, inelastic neutron scattering and the first principles calculations, as an evidence for the generation of structure disorder by K deficiency.

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confidence: 99%

Lattice dynamics of KxRhO2 single crystals

Zhang

Dong

et al. 2015

AIP Advances

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“…A wide range of research fields will be covered; these include crystal-field excitations, phonon densities of states, magnetic excitations from various multifunctional materials including high Tc superconductors, novel magnetic, thermo-electric, ferroelectric and piezoelectric materials; molecular dynamics in hydrogen-bonded and hydrogen storage materials, catalytic materials, cements, soils and rocks; and water dynamics in proteins and ion diffusion in membranes. A polarisation analysis option is also included in the design of the instrument [1].…”

Section: Introductionmentioning

confidence: 99%

“…The neutron wavelength covers from 2.4Å to 6.3Å (14.2 meV to 2.1 meV), delivered by a specially designed and fabricated triple monochromator system, consisting of three banks of highly oriented pyrolytic graphite (HOPG) crystals having 0.5 degree of mosacity [2]. Combined with high speed Fermi choppers, energy resolution in the range 0.06 meV to 1.5 meV can be achieved at the elastic line, while the energy resolution at a desired energy transfer can be optimised through time focusing achieved by adjusting the speed and the sense of rotation of the Fermi chopper to allow the slow neutrons pass the chopper before the fast ones so that they arrive at the detector at the same time [1]. In this paper, the performance of the instrument will be demonstrated with the results of measured energy resolution and flux at the sample position as a function of neutron wavelength and the evaluation on several real systems with quasi-elastic and inelastic a Corresponding author: dyu@ansto.gov.au neutron scatterings.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, the performance of the instrument will be demonstrated with the results of measured energy resolution and flux at the sample position as a function of neutron wavelength and the evaluation on several real systems with quasi-elastic and inelastic a Corresponding author: dyu@ansto.gov.au neutron scatterings. For the general design specifications of the Pelican instrument and descriptions of major components such as monochromator, polarizer, master and slave Fermi choppers, vacuum chambers and detector system, please refer to reference [1]. The commission and performance test of the polarisation analysis system will be presented later elsewhere.…”

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confidence: 99%

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Performance test on PELICAN – a multi-purpose time of flight cold neutron spectrometer

Mole

Kearley

2015

EPJ Web of Conferences

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Abstract. Pelican, a direct geometry multi-purpose cold neutron spectrometer has recently been commissioned at the Bragg Institute, ANSTO. The energy resolution and flux at the sample position as a function of neutron wavelength has been evaluated and time focusing at selected energy transfers has also been demonstrated. Several test experiments of quasi-elastic and inelastic neutron scatterings have been performed and these have indicated the realisation of the design specifications and performance of the instrument.

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“…Radial collimators in the scattered beam of such instruments have been found to effectively reduce the background scattering due to sample environments such as cryostats or furnaces [2]. Such collimators are often used in instrumentation with cold or thermal wavelength neutrons [3][4][5][6][7]. We discuss here the design and performance of a radial collimator for the Wide Angular Range Chopper Spectrometer (ARCS) at the Spallation Neutron Source [8].…”

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The ARCS radial collimator

Stone

Niedziela

Overbay

et al. 2015

EPJ Web of Conferences

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Abstract. We have designed, installed, and commissioned a scattered beam radial collimator for use at the ARCS Wide Angular Range Chopper Spectrometer at the Spallation Neutron Source. The collimator has been designed to work effectively for thermal and epithermal neutrons and with a range of sample environments. Other design considerations include the accommodation of working within a high vacuum environment and having the ability to quickly install and remove the collimator from the scattered beam. We present here characterization of the collimator's performance and methodologies for its effective use.Direct geometry time-of-flight neutron spectrometers often make use of large detector arrays to improve measurement efficiency [1]. Radial collimators in the scattered beam of such instruments have been found to effectively reduce the background scattering due to sample environments such as cryostats or furnaces [2]. Such collimators are often used in instrumentation with cold or thermal wavelength neutrons [3][4][5][6][7]. We discuss here the design and performance of a radial collimator for the Wide Angular Range Chopper Spectrometer (ARCS) at the Spallation Neutron Source [8]. ARCS is a high flux chopper spectrometer that operates with thermal to epithermal wavelength neutrons [9]. Figure 1 illustrates the location and orientation of the radial collimator. The ARCS instrument has two vacuum chambers separated by a large gate valve to facilitate sample environment changes without venting the larger detector vacuum chamber. To accommodate the out-ofplane detector coverage of the instrument, the height of the collimating blades or septa is 622 mm. The inner radius of the collimator is r 1 = 308 mm, and the outer radius is r 2 = 462 mm. The angular spacing between septa is 1.6• . The angular range of the collimator is −30.5• to 138.0 • with a 12.8• wide portion in the forward scattering direction not collimated. This portion was not collimated to eliminate any scattering of the direct beam by the septa. The value of r 2 was chosen to be as large as possible and not interfere with the gate valve. The value of r 1 was chosen to be larger than the most often used sample environments at ARCS. The angular spacing was chosen to remove the background from scattering events outside of a 25 mm radius from the sample center. The collimator resides on a motorized lifting fixture. This allows the collimator to be either in the scattered beam, or stored below the sample environment when it is not needed. When in the operating position, the collimator oscillates with a full range of 1.6• and a period of 21 seconds via a motorized Scotch yoke a e-mail: stonemb@ornl.gov drive mechanism. Further details regarding the design are available in Ref. [8].The septa are 12 micron thick Kapton foils coated on each side with 39 microns of enriched boron carbide ( 10 B 4 C with 10 B > 96%) in an ultra-high vacuum compatible binder. The neutron absorption of 10 B is large and resonance free over a broad range of wavelengths. The collimator b...

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Pelican — a Time of Flight Cold Neutron Polarization Analysis Spectrometer at OPAL

Cited by 94 publications

References 8 publications

Lattice dynamics of KxRhO2 single crystals

Lattice dynamics of KxRhO2 single crystals

Performance test on PELICAN – a multi-purpose time of flight cold neutron spectrometer

The ARCS radial collimator

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