Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Novel Imaging Techniques: Polarized Neutrons and Neutron-Based Magnetic Resonance Imaging
Abstract This chapter describes three rather novel neutron-based imaging methods all of which involve magnetic fields. The first two take advantage of the neutron magnetic moment which makes it sensitive to the presence of magnetic fields. In the first application the Larmor precession of the neutron in a magnetic field is used to produce two- and three-dimensional (3D) visualization of magnetic field distributions in free space and in bulk materials. In the second potential application, the Larmor precession is used as a measure of the material density through which the beam passes. Although this technique of spin contrast imaging is still very much in the concept stage, initial estimates show that it is feasible with new sources and may open up the possibility of obtaining 3D images without moving the sample. Polarization of the nuclei in a material can also provide unique ways of imaging a system. By partially polarizing the nuclei with a sufficiently large magnetic field, the Zeeman splitting of the nuclei can be detected by high-resolution neutron spectroscopy. If the field is then reduced, the time for the Zeeman splitting to relax to the equilibrium value is a measure of the nuclear relaxation time; this is the physical quantity measured in magnetic resonance imaging. A full image of the relaxation times with respect to position could then be obtained by rastering the sample in the neutron beam.
Novel Imaging Techniques: Polarized Neutrons and Neutron-Based Magnetic Resonance Imaging
Abstract This chapter describes three rather novel neutron-based imaging methods all of which involve magnetic fields. The first two take advantage of the neutron magnetic moment which makes it sensitive to the presence of magnetic fields. In the first application the Larmor precession of the neutron in a magnetic field is used to produce two- and three-dimensional (3D) visualization of magnetic field distributions in free space and in bulk materials. In the second potential application, the Larmor precession is used as a measure of the material density through which the beam passes. Although this technique of spin contrast imaging is still very much in the concept stage, initial estimates show that it is feasible with new sources and may open up the possibility of obtaining 3D images without moving the sample. Polarization of the nuclei in a material can also provide unique ways of imaging a system. By partially polarizing the nuclei with a sufficiently large magnetic field, the Zeeman splitting of the nuclei can be detected by high-resolution neutron spectroscopy. If the field is then reduced, the time for the Zeeman splitting to relax to the equilibrium value is a measure of the nuclear relaxation time; this is the physical quantity measured in magnetic resonance imaging. A full image of the relaxation times with respect to position could then be obtained by rastering the sample in the neutron beam.
Novel Imaging Techniques: Polarized Neutrons and Neutron-Based Magnetic Resonance Imaging
Kardjilov, N. (Autor:in) / H. Lee, W. T. (Autor:in) / Granroth, G. E. (Autor:in)
01.01.2009
17 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
Polarized neutrons , Magnetic fields , Magnetic resonance imaging , Spin-echo , Time-of-flight , three-dimensional imaging Material Science , Biomedical Engineering , Imaging / Radiology , Condensed Matter , Continuum Mechanics and Mechanics of Materials , Characterization and Evaluation of Materials
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