Browsing by Author "Tong, X"

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    The CG1 instrument development test station at the high flux isotope reactor
    (Elsevier, 2011-04-01) Crow, L; Robertson, L; Bilheux, H; Fleenor, M; Iverson, E; Tong, X; Stoica, D; Lee, WT
    The CG1 instrument development station at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory began commissioning operation in 2009. When completed, the station will have four beams. CG1A is a 4.22 angstrom monochromatic beam intended for spin-echo resolved grazing incidence scattering (SERGIS) prototype development. Initial beam operation and characterization are in progress. CG1B will be a 2.35 angstrom monochromatic beam for a 2-axis utility diffractometer for sample alignment and monochromator development. CG1C will have a double-bounce monochromator system, which will produce a variable wavelength beam from about 1.8-6.4 angstrom, and will be used for imaging and optical development. The CG1D beam is a single chopper time-of-flight system, used for instrument prototype and component testing. The cold neutron spectrum, with an integrated flux of about 2.7 x 10(9) n/cm(2) s, has a guide cutoff at 0.8 angstrom and useful wavelengths greater than 20 angstrom. Initial results from CG1 include spectral characterization, imaging tests, detector trials, and polarizer tests. An overview of recent tests will be presented, and upcoming instrument prototype efforts will be described. (C) 2010 Elsevier B.V. All rights reserved.
  • No Thumbnail Available
    Item
    In-situ polarized 3 He-based neutron polarization analyzer for SNS magnetism reflectometer
    (Insitute of Physics, 2010-12-16) Lee, WT; Tong, X; Pierce, J; Fleenor, M; Ismaili, A; Robertson, JL; Chen, WC; Gentile, TR; Hailemariam, A; Goyette, R; Parizzi, A; Lauter, V; Klose, F; Kaiser, H; Lavelle, C; Baxter, DV; Jones, GL; Wexler, J; McCollum, L
    We report here the construction and neutron transmission test results of an in-situ polarized 3 He-based neutron polarization analyzer system for the Magnetism Reflectometer at the Spallation Neutron Source, Oak Ridge National Laboratory. The analyzer uses the Spin-Exchange Optical Pumping method to polarize the 3 He nuclei of a cell of 3 He gas. Polarized neutrons scattered from the sample are intercepted by the polarized 3 He gas which strongly absorbs neutrons in one spin-state while allowing most neutrons in the other spin-state to pass through. To maintain a stable analyzing efficiency during an experiment, the 3 He gas is continuously polarized in - situ on the instrument. Neutron transmission measurements showed that 73% 3 He polarization was reached in this setup. © 2010, Insitute of Physics.
  • No Thumbnail Available
    Item
    Spin exchange optical pumping based polarized He-3 filling station for the hybrid spectrometer at the spallation neutron source
    (American Institute of Physics, 2013-06-01) Jiang, CY; Tong, X; Brown, DR; Culbertson, H; Graves-Brook, MK; Hagen, ME; Kadron, B; Lee, WT; Robertson, JL; Winn, B
    The Hybrid Spectrometer (HYSPEC) is a new direct geometry spectrometer at the Spallation Neutron Source at the Oak Ridge National Laboratory. This instrument is equipped with polarization analysis capability with 60 degrees horizontal and 15 degrees vertical detector coverages. In order to provide wide angle polarization analysis for this instrument, we have designed and built a novel polarized He-3 filling station based on the spin exchange optical pumping method. It is designed to supply polarized He-3 gas to HYSPEC as a neutron polarization analyzer. In addition, the station can optimize the He-3 pressure with respect to the scattered neutron energies. The depolarized He-3 gas in the analyzer can be transferred back to the station to be repolarized. We have constructed the prototype filling station. Preliminary tests have been carried out demonstrating the feasibility of the filling station. Here, we report on the design, construction, and the preliminary results of the prototype filling station. © 2013, American Institute of Physics.
  • Thumbnail Image
    Item
    Thermal batteries based on inverse barocaloric effects
    (Science Advances, 2023-02) Zhang, Z; Li, K; Lin, SC; Song, R; Yu, DH; Wang, Y; Wang, JF; Kawaguchi, S; Zhang, Z; Yu, CY; Li, XD; Chen, J; He, LH; Mole, RA; Yuan, B; Ren, QY; Qian, K; Cai, ZL; Yu, JG; Wang, MC; Zhao, CY; Tong, X; Zhang, ZD; Li, B
    To harvest and reuse low-temperature waste heat, we propose and realize an emergent concept-barocaloric thermal batteries based on the large inverse barocaloric effect of ammonium thiocyanate (NH4SCN). Thermal charging is initialized upon pressurization through an order-to-disorder phase transition, and the discharging of 43 J g-1 takes place at depressurization, which is 11 times more than the input mechanical energy. The thermodynamic equilibrium nature of the pressure-restrained heat-carrying phase guarantees stable long-duration storage. The barocaloric thermal batteries reinforced by their solid microscopic mechanism are expected to substantially advance the ability to take advantage of waste heat. Copyright © 2023 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).
  • Thumbnail Image
    Item
    Two pressure cells for quasielastic and inelastic neutron scatterings
    (EDP Sciences, 2022-11-17) Yuan, B; Mole, RA; Wang, CW; Shumack, A; White, R; Li, B; Tong, X; Yu, DH
    Two clamp pressure cells for QENS and INS have been developed. One is a hybrid CuBe/NiCrAl cell which is for relative high pressure up to 2.5 GPa and another one is made from high strength aluminium alloy (mesolite NA723) with pressure up to 0.5 GPa. The sample volume is 0.3 mL and 1 mL, respectively. The pressure cells have been thoroughly calibrated and tested. In addition, the contribution to phonon density of states from the pressure cells has been evaluated. Measurements of the phonon density of states for two perfluorocarbon polymer liquids FOMBLIN oil and Fluorinert have indicated that they are suitable to serve as the low background pressure transmission media for high pressure INS experiments. The applications of the pressure cells for INS and QENS are demonstrated by studies of pressure-induced phase transition of plastic crystals. © The Authors, published by EDP Sciences, 2022. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/).
  • Thumbnail Image
    Item
    Two-dimensional quantum universality in the spin-1/2 triangular-lattice quantum antiferromagnet Na2BaCo(PO4)2
    (Proceedings of the National Academy of Sciences, 2022-12-15) Sheng, JM; Wang, L; Candini, A; Jiang, W; Huang, L; Xi, B; Zhao, J; Ge, H; Zhao, N; Fu, Y; Ren, J; Yang, J; Miao, P; Tong, X; Yu, D; Wang, S; Liu, Q; Kofu, M; Mole, RA; Biasiol, G; Yu, DH; Zaliznyak, IA; Mei, JW; Wu, L
    An interplay of geometrical frustration and strong quantum fluctuations in a spin-1/2 triangular-lattice antiferromagnet (TAF) can lead to exotic quantum states. Here, we report the neutron-scattering, magnetization, specific heat, and magnetocaloric studies of the recently discovered spin-1/2 TAF Na2BaCo(PO4)2, which can be described by a spin-1/2 easy axis XXZ model. The zero-field neutron diffraction experiment reveals an incommensurate antiferromagnetic ground state with a significantly reduced ordered moment of about 0.54(2) μB/Co. Different magnetic phase diagrams with magnetic fields in the ab plane and along the easy c-axis were extracted based on the magnetic susceptibility, specific heat, and elastic neutron-scattering results. In addition, two-dimensional (2D) spin dispersion in the triangular plane was observed in the high-field polarized state, and microscopic exchange parameters of the spin Hamiltonian have been determined through the linear spin wave theory. Consistently, quantum critical behaviors with the universality class of d = 2 and νz = 1 were established in the vicinity of the saturation field, where a Bose–Einstein condensation (BEC) of diluted magnons occurs. The newly discovered quantum criticality and fractional magnetization phase in this ideal spin-1/2 TAF present exciting opportunities for exploring exotic quantum phenomena. © 2022 the Author(s). Published by PNAS. This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).