Development and applications of the reverse neutron time-of-flight method with Fourier-type beam chopper: Dissertation

Olli Antson

    Research output: ThesisDissertationCollection of Articles

    Abstract

    The neutron powder diffraction method has been applied to the crystal structure analysis of high temperature superconductors such as La1.8SrO.2Cu04-y, YBa2Cu307-y and Bi2Sr2CaCu208+y, optically active yttriumformate Y(HC00)3, and ß phase of deuterated acetonitrile, CD3CN. The structural information, containing symmetry, positional and thermal parameters, occupation factors and the order parameter, was obtained by measuring the coherent elastic scattering cross-section. The Rietveld profile refinement method was used for the extraction of structural parameters from experimental data. The diffraction spectra were obtained by measuring the time of flight distribution of neutrons with a Fourier type beam chopper. The neutron diffraction spectrum is created by the on line synthesis of the cross-correlation function between the beam modulation function and the detector intensity. Such an operational mode, called the reverse time- of flight method, has many unique properties. The possibility of filtering out a low frequency part of a diffraction spectrum, eg. incoherent background, by a properly selected band pass filter has been studied. One of the practical applications of the reverse time of flight method, the Mini Sfinks facility, is described with technical details, and its operational characteristics are compared with other high resolution instruments.
    Original languageEnglish
    QualificationDoctor Degree
    Awarding Institution
    • Helsinki University of Technology
    Award date18 Oct 1991
    Place of PublicationEspoo
    Publisher
    Print ISBNs951-38-3956-7
    Publication statusPublished - 1991
    MoE publication typeG5 Doctoral dissertation (article)

    Fingerprint

    electric choppers
    neutrons
    reaction time
    diffraction
    coherent scattering
    bandpass filters
    high temperature superconductors
    scattering cross sections
    occupation
    cross correlation
    acetonitrile
    neutron diffraction
    elastic scattering
    low frequencies
    modulation
    crystal structure
    high resolution
    detectors
    symmetry
    synthesis

    Keywords

    • neutrons
    • neutron diffraction
    • powders
    • super conductors
    • time-of-flight method
    • beam pulsers
    • Fourier analysis

    Cite this

    Antson, Olli. / Development and applications of the reverse neutron time-of-flight method with Fourier-type beam chopper : Dissertation. Espoo : VTT Technical Research Centre of Finland, 1991. 145 p.
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    title = "Development and applications of the reverse neutron time-of-flight method with Fourier-type beam chopper: Dissertation",
    abstract = "The neutron powder diffraction method has been applied to the crystal structure analysis of high temperature superconductors such as La1.8SrO.2Cu04-y, YBa2Cu307-y and Bi2Sr2CaCu208+y, optically active yttriumformate Y(HC00)3, and {\ss} phase of deuterated acetonitrile, CD3CN. The structural information, containing symmetry, positional and thermal parameters, occupation factors and the order parameter, was obtained by measuring the coherent elastic scattering cross-section. The Rietveld profile refinement method was used for the extraction of structural parameters from experimental data. The diffraction spectra were obtained by measuring the time of flight distribution of neutrons with a Fourier type beam chopper. The neutron diffraction spectrum is created by the on line synthesis of the cross-correlation function between the beam modulation function and the detector intensity. Such an operational mode, called the reverse time- of flight method, has many unique properties. The possibility of filtering out a low frequency part of a diffraction spectrum, eg. incoherent background, by a properly selected band pass filter has been studied. One of the practical applications of the reverse time of flight method, the Mini Sfinks facility, is described with technical details, and its operational characteristics are compared with other high resolution instruments.",
    keywords = "neutrons, neutron diffraction, powders, super conductors, time-of-flight method, beam pulsers, Fourier analysis",
    author = "Olli Antson",
    year = "1991",
    language = "English",
    isbn = "951-38-3956-7",
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    publisher = "VTT Technical Research Centre of Finland",
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    Development and applications of the reverse neutron time-of-flight method with Fourier-type beam chopper : Dissertation. / Antson, Olli.

    Espoo : VTT Technical Research Centre of Finland, 1991. 145 p.

    Research output: ThesisDissertationCollection of Articles

    TY - THES

    T1 - Development and applications of the reverse neutron time-of-flight method with Fourier-type beam chopper

    T2 - Dissertation

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    PY - 1991

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    N2 - The neutron powder diffraction method has been applied to the crystal structure analysis of high temperature superconductors such as La1.8SrO.2Cu04-y, YBa2Cu307-y and Bi2Sr2CaCu208+y, optically active yttriumformate Y(HC00)3, and ß phase of deuterated acetonitrile, CD3CN. The structural information, containing symmetry, positional and thermal parameters, occupation factors and the order parameter, was obtained by measuring the coherent elastic scattering cross-section. The Rietveld profile refinement method was used for the extraction of structural parameters from experimental data. The diffraction spectra were obtained by measuring the time of flight distribution of neutrons with a Fourier type beam chopper. The neutron diffraction spectrum is created by the on line synthesis of the cross-correlation function between the beam modulation function and the detector intensity. Such an operational mode, called the reverse time- of flight method, has many unique properties. The possibility of filtering out a low frequency part of a diffraction spectrum, eg. incoherent background, by a properly selected band pass filter has been studied. One of the practical applications of the reverse time of flight method, the Mini Sfinks facility, is described with technical details, and its operational characteristics are compared with other high resolution instruments.

    AB - The neutron powder diffraction method has been applied to the crystal structure analysis of high temperature superconductors such as La1.8SrO.2Cu04-y, YBa2Cu307-y and Bi2Sr2CaCu208+y, optically active yttriumformate Y(HC00)3, and ß phase of deuterated acetonitrile, CD3CN. The structural information, containing symmetry, positional and thermal parameters, occupation factors and the order parameter, was obtained by measuring the coherent elastic scattering cross-section. The Rietveld profile refinement method was used for the extraction of structural parameters from experimental data. The diffraction spectra were obtained by measuring the time of flight distribution of neutrons with a Fourier type beam chopper. The neutron diffraction spectrum is created by the on line synthesis of the cross-correlation function between the beam modulation function and the detector intensity. Such an operational mode, called the reverse time- of flight method, has many unique properties. The possibility of filtering out a low frequency part of a diffraction spectrum, eg. incoherent background, by a properly selected band pass filter has been studied. One of the practical applications of the reverse time of flight method, the Mini Sfinks facility, is described with technical details, and its operational characteristics are compared with other high resolution instruments.

    KW - neutrons

    KW - neutron diffraction

    KW - powders

    KW - super conductors

    KW - time-of-flight method

    KW - beam pulsers

    KW - Fourier analysis

    M3 - Dissertation

    SN - 951-38-3956-7

    T3 - Technical Research Centre of Finland. Publications

    PB - VTT Technical Research Centre of Finland

    CY - Espoo

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