The Experts below are selected from a list of 15177 Experts worldwide ranked by ideXlab platform
J V Kratz - One of the best experts on this subject based on the ideXlab platform.
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Neutron Velocity distribution from a superthermal solid 2h2 ultracold Neutron source
European Physical Journal A, 2008Co-Authors: I Altarev, M Daum, A Frei, E Gutsmiedl, G Hampel, F J Hartmann, W Heil, A Knecht, J V KratzAbstract:We have determined for the first time the Velocity distribution of Neutrons from a solid 2 H 2 ultracold Neutron (UCN) source. The spectrum rises sharply above 4.5m/s and has a maximum around 7m/s after transport in an 8m long guide. The number of Neutrons in the UCN Velocity range (< 7m/s) may be increased by a factor of two by placing the experiment 1m above the UCN source level.
A Knecht - One of the best experts on this subject based on the ideXlab platform.
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Neutron Velocity distribution from a superthermal solid 2h2 ultracold Neutron source
European Physical Journal A, 2008Co-Authors: I Altarev, M Daum, A Frei, E Gutsmiedl, G Hampel, F J Hartmann, W Heil, A Knecht, J V KratzAbstract:We have determined for the first time the Velocity distribution of Neutrons from a solid 2 H 2 ultracold Neutron (UCN) source. The spectrum rises sharply above 4.5m/s and has a maximum around 7m/s after transport in an 8m long guide. The number of Neutrons in the UCN Velocity range (< 7m/s) may be increased by a factor of two by placing the experiment 1m above the UCN source level.
S Baechler - One of the best experts on this subject based on the ideXlab platform.
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new features in cold Neutron radiography and tomography part ii applied energy selective Neutron radiography and tomography
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2003Co-Authors: Nikolay Kardjilov, S Baechler, Manuel Dierick, J Jolie, E Lehmann, T Materna, M Basturk, Burkhard Schillinger, Peter VontobelAbstract:Abstract The Neutron attenuation coefficient drops for many solid materials quite drastically at a defined cold Neutron energy known as a Bragg-cut-off in the cross-section diagrams. In many cases, the drop in attenuation for the corresponding elements is significant and this behavior can be exploited to change the material contrast in radiography and tomography images by modifying the spectrum of the applied Neutron beam. The energy-dependent experiments were performed at the Prompt Gamma-ray Activation beam line where the irradiation position is at the end of a curved Neutron guide, which delivers cold Neutrons from the spallation source SINQ (PSI, Switzerland). This beam position gave the opportunity to perform radiography and tomography at low Neutron energies. An effective monochromatization of the primary Neutron beam was obtained by using a Neutron Velocity selector. The intensity of the modified beam was still reasonable for radiography images at different Neutron energies and the experiments were performed in relatively short measuring times. A variety of samples were studied to illustrate possible applications of energy-selective radiography and tomography. This new Neutron imaging technique provided encouraging results and projects of developing permanent facilities for such investigations at PSI and FRM II are under study.
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new features in cold Neutron radiography and tomography part i thinner scintillators and a Neutron Velocity selector to improve the spatial resolution
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2002Co-Authors: S Baechler, Nikolay Kardjilov, Manuel Dierick, J Jolie, G Kuhne, E Lehmann, T MaternaAbstract:Abstract The tomography setup developed at the PGA facility of the Swiss spallation source SINQ has provided encouraging results in the field of cold Neutron imaging. Performances of the detection system based on a CCD camera and a converter screen have been recently improved using 6 LiF/ZnS:Ag scintillators with different thickness. Indeed, reducing the layer of the scintillator improved considerably the spatial resolution while keeping a reasonable efficiency. Furthermore, a Neutron Velocity selector was temporarily added to the setup to perform radiography and tomography experiments with monochromatic Neutron beams. Basic properties of transmitted beams were studied to assess the applicability of this device in Neutron imaging. Of interest was the enhancement of the L / D -ratio by selecting Neutron beams of short wavelengths. Cold Neutron tomography demonstrated to be a useful technique in various spheres of activity, such as aerospatial industry or radioactive waste storage. Various applications of the Neutron Velocity selector are described in the second part, namely, New features in cold Neutron radiography and tomography—Part II: Applied energy-selective Neutron radiography and tomography.
Nikolay Kardjilov - One of the best experts on this subject based on the ideXlab platform.
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new features in cold Neutron radiography and tomography part ii applied energy selective Neutron radiography and tomography
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2003Co-Authors: Nikolay Kardjilov, S Baechler, Manuel Dierick, J Jolie, E Lehmann, T Materna, M Basturk, Burkhard Schillinger, Peter VontobelAbstract:Abstract The Neutron attenuation coefficient drops for many solid materials quite drastically at a defined cold Neutron energy known as a Bragg-cut-off in the cross-section diagrams. In many cases, the drop in attenuation for the corresponding elements is significant and this behavior can be exploited to change the material contrast in radiography and tomography images by modifying the spectrum of the applied Neutron beam. The energy-dependent experiments were performed at the Prompt Gamma-ray Activation beam line where the irradiation position is at the end of a curved Neutron guide, which delivers cold Neutrons from the spallation source SINQ (PSI, Switzerland). This beam position gave the opportunity to perform radiography and tomography at low Neutron energies. An effective monochromatization of the primary Neutron beam was obtained by using a Neutron Velocity selector. The intensity of the modified beam was still reasonable for radiography images at different Neutron energies and the experiments were performed in relatively short measuring times. A variety of samples were studied to illustrate possible applications of energy-selective radiography and tomography. This new Neutron imaging technique provided encouraging results and projects of developing permanent facilities for such investigations at PSI and FRM II are under study.
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further developments and applications of radiography and tomography with thermal and cold Neutrons
2003Co-Authors: Nikolay KardjilovAbstract:In the current study various new experimental methods and computation procedures in the field of Neutron radiography and tomography are presented. These methods have a significant technical importance in the non-destructive material investigations. Different techniques for a contrast enhancement, contrast variations and an increase of the image sharpness were developed. In a beam geometry with a high lateral coherency of the Neutron waves for the first time phase contrast radiography experiments with polychromatic Neutrons were performed and analytically simulated. Therewith very fine structures were visualized which was impossible with the standard absorption radiography technique. By the utilization of a Neutron Velocity selector radiography and tomography experiments below and above the Bragg cut offs for objects, composed from different materials, were performed and the possibility for a material identification was tested. Using the method of the Neutron topography the quality of single crystals was investigated. For some of these experiments Monte Carlo simulations were performed using the powerful MCNP-code. This method was used also for the development of a mobile Neutron radiography setup. Some of the achieved developments will be used at the radiography and tomography facilities at the new research reactor FRM II in Munich, Germany.
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new features in cold Neutron radiography and tomography part i thinner scintillators and a Neutron Velocity selector to improve the spatial resolution
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2002Co-Authors: S Baechler, Nikolay Kardjilov, Manuel Dierick, J Jolie, G Kuhne, E Lehmann, T MaternaAbstract:Abstract The tomography setup developed at the PGA facility of the Swiss spallation source SINQ has provided encouraging results in the field of cold Neutron imaging. Performances of the detection system based on a CCD camera and a converter screen have been recently improved using 6 LiF/ZnS:Ag scintillators with different thickness. Indeed, reducing the layer of the scintillator improved considerably the spatial resolution while keeping a reasonable efficiency. Furthermore, a Neutron Velocity selector was temporarily added to the setup to perform radiography and tomography experiments with monochromatic Neutron beams. Basic properties of transmitted beams were studied to assess the applicability of this device in Neutron imaging. Of interest was the enhancement of the L / D -ratio by selecting Neutron beams of short wavelengths. Cold Neutron tomography demonstrated to be a useful technique in various spheres of activity, such as aerospatial industry or radioactive waste storage. Various applications of the Neutron Velocity selector are described in the second part, namely, New features in cold Neutron radiography and tomography—Part II: Applied energy-selective Neutron radiography and tomography.
I Altarev - One of the best experts on this subject based on the ideXlab platform.
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Neutron Velocity distribution from a superthermal solid 2h2 ultracold Neutron source
European Physical Journal A, 2008Co-Authors: I Altarev, M Daum, A Frei, E Gutsmiedl, G Hampel, F J Hartmann, W Heil, A Knecht, J V KratzAbstract:We have determined for the first time the Velocity distribution of Neutrons from a solid 2 H 2 ultracold Neutron (UCN) source. The spectrum rises sharply above 4.5m/s and has a maximum around 7m/s after transport in an 8m long guide. The number of Neutrons in the UCN Velocity range (< 7m/s) may be increased by a factor of two by placing the experiment 1m above the UCN source level.