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One of the most noteworthy aspects of computed tomography (CT) based on the nuclear resonance fluorescence (NRF) transmission method is the isotope selectivity that makes it possible to discern an isotope of interest from other isotopes within a sample. We experimentally obtained a three-dimensional (3D) isotope-selective CT image based on the NRF transmission method (3D NRF-CT) for the enriched lead isotope distribution of 208Pb in a cylindrical holder in a previous study. The cylindrical holder's diameter and height are 25 mm and 20 mm, respectively. The NRF-CT imaging technique requires a considerable data accumulation time. It took 48 h to obtain an image with a resolution of 4 mm/pixel in the horizontal plane and 8 mm/pixel in the vertical plane using a laser Compton scattering (LCS) gamma-ray beam with a beam size of 2 mm and a flux density of 10 photons/s/eV. Improving the NRF-CT image resolution with the existing hardware is challenging. Therefore, we proposed an alternative method to improve the NRF-CT image resolution using the fusion visualization (FV) technique by combining the NRF-CT image including isotopic information with a gamma-CT image, which provides better pixel resolution. The 3D gamma-CT image for the same sample was measured at the same beamline BL1U in the ultraviolet synchrotron orbital radiation-III (UVSOR-III) synchrotron radiation facility at the Institute of Molecular Science at the National Institutes of Natural Sciences in Japan under similar experimental conditions except for the LCS gamma-ray beam flux and beam size. Obtaining a 3D gamma-CT image with a resolution of 1 mm/pixel took 5 h using an LCS gamma-ray beam with a beam size of 1 mm and a flux density of 0.7 photons/s/eV. The data processing of the FV technique has been developed, and the 3D NRF-CT image quality was improved. [ABSTRACT FROM AUTHOR]

Combining the nuclear resonance fluorescence (NRF) transmission method with computed tomography (CT) can be a novel method for imaging the isotope distributions, which is indispensable in nuclear engineering. We performed an experiment to reconstruct a three-dimensional NRF-CT image with isotope selectivity of enriched lead isotope rods (208Pb) together with a set of different rods, including another enriched isotope (206Pb), iron, and aluminum rods, inserted into a cylindrical aluminum holder. Using a laser Compton scattering (LCS) gamma ray beam with a 5.528 MeV maximum energy, 2 mm beam size, and 10 photon·s−1·eV−1 flux density, which is available at the BL1U beamline in the ultraviolet synchrotron orbital radiation-III (UVSOR-III) synchrotron radiation facility at the Institute of Molecular Science at the National Institutes of Natural Sciences in Japan, and we excited the Jπ = 1− NRF level at 5.512 MeV in 208Pb. An isotope-selective three-dimensional NRF-CT image of the 208Pb isotope distribution was experimentally obtained for the first time with a pixel resolution of 4 mm in the horizontal plane. [ABSTRACT FROM AUTHOR]

• First-ever magnetic Compton profiles (MCPs) of non-stoichiometric Ni 0.9-x Pr x Fe 2.1 O 4 inverse spinel ferrites. • Decomposed experimental MCPs into constituent profiles of Ni, Fe, Pr-4f and diffuse electrons. • Validated MCP based total and site-specific spin moments using FP-LAPW calculations. • Explored role of orbital magnetic moments using MCP data and magnetization data. • Revealed effect of Pr-4f states in amending the spin moments and electronic properties. Magnetic Compton profiles of 5 % and 15 % Pr-doped non-stoichiometric NiFe 2 O 4 have been measured using synchrotron radiations of energy 182.65 keV at SPring-8, Japan. An analysis of MCPs measured at 6 and 300 K show that the total spin moment decreases with increasing temperature and Pr concentration in Ni 0.9-x Pr x Fe 2.1 O 4 which is consistent with the magnetic moment (spin + orbital) as observed from magnetization measurements data. Spin moments at different sites are deduced using decomposition of MCPs in the elemental profiles of Ni, Pr-4f, Fe and diffused electrons. Spin moments at Ni-site have been found to play crucial role in emergence of absolute spin moments. Spin moments at Pr-site is aligned antiparallel to that of Ni and Fe sites. The orbital magnetic moment is also deduced from the subtraction of MCP based spin moments from the magnetization data. Theoretical FP-LAPW based total and atom specific spin moments are found in consonance with the MCP based data. Total and spin projected density of states are also computed using the FP-LAPW method to validate role of Pr-4f and Fe-3d (O h) states in amending the total magnetic moment with Pr concentration. The M−H based saturation magnetization derived at 6 and 300 K temperature show that the saturation magnetic moments reduce from 2.21 → 2.05 μ B /f.u. at 6 K and 2.10 → 1.98 μ B /f.u. at 300 K with increase in Pr concentration from 5 % → 15 %. On the basis of hysteresis curve and coercive force, both the doped compounds show soft magnetism. [ABSTRACT FROM AUTHOR]

• Measured spin momentum densities for Ni/Co doped LCMO using synchrotron radiations. • Elaborated peculiarities of magnetism using experimental MCPs and DFT computations. • Revealed mixed valence states of Mn and its ferromagnetic interaction with Ni and Co. • Explored Z-in and Z-out JT distortion in LCMO and after Ni and Co doping. • Disseminated guidelines for interpretation of MCP data using ab-initio computations. Magnetic Compton profiles (MCPs) of La 0.7 Ca 0.3 Mn 0.95 (Ni/Co) 0.05 O 3 between 8 and 250 K have been measured using high energy inelastic scattering at SPring-8, Japan. For a quantitative analysis on amendment of magnetic properties, temperature-dependent experimental MCPs are decomposed into constituent profiles related to Mn, Ni/Co and itinerant (diffuse) electrons. Decomposed profiles unambiguously show that Mn-3d electrons are ferromagnetically coupled with Ni/Co ions while itinerant electrons are linked anti-ferromagnetically with Mn-3d and Ni/Co-3d electrons. An annotation of MCP and VSM data depicts that the orbital magnetic moments are anti-ferromagnetically coupled to total spin moments. Variation in magnetic response in undoped and Ni/Co doped perovskites is devoted to formation of mixed valence states of Mn atom. The spin contribution at different sites are found to be in tune with present density functional theory (DFT) based calculations which are thoroughly analyzed on the basis of changes in the e g and t 2g states of Mn, Ni/Co caused by Jahn-Teller distortion. Present MCP data and DFT calculations set guidelines to probe the reliable origin to examine magnetic response and half-metallic properties of such manganites. [ABSTRACT FROM AUTHOR]

This paper proposes a Compton CT technique which accurately reconstructs the image of the radiation source distribution in the object cross section from the data observed by Compton scattering. The source space tree algorithm (SSTA) is proposed as an image reconstruction method in Compton CT. The method consists of reconstructing the source distribution by summing the weights assigned to the voxels intersecting the surface of a cone determined by the Compton scattering angle. In this process, it is necessary to make a decision about the intersection between the voxels composing the back-projection space and the cone surface. In the conventional method, the spherical region is used in making the decision. This may produce an incorrect judgment of intersection, resulting in an artifact on the image. In the proposed method, a cube is used instead of a sphere. This makes the intersection decision more accurate, resulting in reconstruction of the image without artifacts. The effectiveness of the proposed method is verified by simulations. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(11): 1–9, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10496 [ABSTRACT FROM AUTHOR]