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

Olli Antson

Research output: ThesisDissertation

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",
series = "Technical Research Centre of Finland. Publications",
publisher = "VTT Technical Research Centre of Finland",
number = "82",
address = "Finland",
school = "Helsinki University of Technology",

}

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: ThesisDissertation

TY - THES

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

T2 - Dissertation

AU - Antson, Olli

PY - 1991

Y1 - 1991

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

ER -