The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
I. Johnson - One of the best experts on this subject based on the ideXlab platform.
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wavelength shifter strips and g apd arrays for the read out of the z Coordinate in Axial pet modules
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2008Co-Authors: Annabel Braem, Julien Seguinot, W. Lustermann, D. Schinzel, Eduardo Nappi, Christian Joram, Peter Weilhammer, Enrico Chesi, A. Rudge, I. JohnsonAbstract:Abstract The measurements presented in this paper are related to the development of a PET camera based on a 3-D Axial geometry with excellent 3-D spatial, timing and energy resolution. The detector modules consist of matrices of long Axially oriented scintillation crystal bars, which are individually coupled to photodetectors. The Axial Coordinate is derived from wavelength shifting (WLS) plastic strips orthogonally interleaved between the crystal bars and readout by G-APD arrays. We report on results from measurements with two LYSO crystal bars, read with PMTs, and two WLS strips readout with G-APD devices from Hamamatsu (called MPPC). The WLS strips are positioned orthogonally underneath the LYSO bars. Yields of about 80 photoelectrons from the WLS strips for an energy deposition in the LYSO crystals equivalent to the absorption of 511 keV photons are observed. The Axial Coordinate in the LYSO bars is reconstructed with a precision of about 1.9 mm (FWHM) using a digital reconstruction method. The resolution of an analog Coordinate reconstruction method, which uses the pulse height measurement from the WLS strips is 2.8 mm (FWHM). This resolution is still compromised by the availability of only two WLS strips and will improve with a full stack of LYSO crystals interleaved with WLS strip arrays, which is presently under development for a PET demonstrator set-up.
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A Demonstrator for a new Axial PET Concept
2008 IEEE Nuclear Science Symposium Conference Record, 2008Co-Authors: E. Bolle, Annabel Braem, Enrico Chesi, C. Casella, G. Dissertori, N. Clinthorne, E. Cochran, L. Djambazov, K. Honscheid, I. JohnsonAbstract:In PET imaging, improving sensitivity while maintaining very good spatial resolution is crucial. To achieve this goal, we propose a novel concept of PET scanner, with Axially arranged crystals, providing a high sensitivity and a 3D reconstruction of the gamma interaction point. The trans-Axial Coordinate is given by the crystal hit, while the z Coordinate is reconstructed by the weighted distribution of light escaping the crystal and entering into an array of Wave Length Shifting (WLS) strips interleaving the crystal layers. This novel configuration allows full identification of Compton interactions in the crystals that can be included in image reconstruction thus enhancing the sensitivity. We present preliminary results obtained by a small prototype consisting of 4×4 crystals with orthogonally interleaved WLS strips. Experimental data are compared to simulated data.
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high precision Axial Coordinate readout for an Axial 3 d pet detector module using a wave length shifter strip matrix
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2007Co-Authors: Annabel Braem, Julien Seguinot, W. Lustermann, D. Schinzel, Eduardo Nappi, Christian Joram, Peter Weilhammer, Enrico Chesi, I. Johnson, D RenkerAbstract:We describe a novel method to extract the Axial Coordinate from a matrix of long Axially oriented crystals, which is based on wavelength shifting plastic strips. The method allows building compact 3-D Axial gamma detector modules for PET scanners with excellent 3-dimensional spatial, timing and energy resolution while keeping the number of readout channels reasonably low. A voxel resolution of about 10 mm 3 is expected. We assess the performance of the method in two independent ways, using classical PMTs and G-APDs to read out the LYSO (LSO) scintillation crystals and the wavelength shifting strips. We
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High precision Axial Coordinate readout for an Axial 3-D PET detector module using a wave length shifter strip matrix
Nuclear Instruments and Methods in Physics Research Section A: Accelerators Spectrometers Detectors and Associated Equipment, 2007Co-Authors: Annabel Braem, Julien Seguinot, W. Lustermann, D. Schinzel, R. De Leo, Eduardo Nappi, Christian Joram, Peter Weilhammer, Enrico Chesi, I. JohnsonAbstract:We describe a novel method to extract the Axial Coordinate from a matrix of long Axially oriented crystals, which is based on wavelength shifting (WLS) plastic strips. The method allows building compact 3-D Axial gamma detector modules for PET scanners with excellent 3-D spatial, timing and energy resolution while keeping the number of readout channels reasonably low. A voxel resolution of about 10 mm3is expected. We assess the performance of the method in two independent ways, using classical PMTs and G-APDs to read out the LYSO (LSO) scintillation crystals and the WLS strips. We observe yields in excess of 35 photoelectrons from the strips for a 511 keV gamma and reconstruct the Axial Coordinate with a precision of about 2.5 mm (FWHM). © 2007 Elsevier B.V. All rights reserved.
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Wave length shifter strips and G-APD arrays for the read-out of the z-Coordinate in Axial PET modules
2007 IEEE Nuclear Science Symposium Conference Record, 2007Co-Authors: Annabel Braem, Julien Seguinot, W. Lustermann, D. Schinzel, Eduardo Nappi, Christian Joram, Peter Weilhammer, Enrico Chesi, A. Rudge, I. JohnsonAbstract:The measurements presented in this paper are related to the development of a PET camera based on a 3D Axial geometry with excellent 3-dimensional spatial, timing and energy resolution. The detector modules under development consist of matrices of long Axially oriented scintillation crystal bars, which are individually coupled to photodetectors. The Axial Coordinate is derived from Wave Length Shifting (WLS) plastic strips orthogonally interleaved between the crystal bars and readout by G-APD arrays. We report on results from measurements with two LYSO crystal bars, read with PMTs, and two WLS strips readout with G-APD devices from Hamamatsu (called MPPC). The WLS strips are positioned orthogonally underneath the LYSO bars. Yields of about 80 photoelectrons from the WLS strips for an energy deposition in the LYSO crystals equivalent to the absorption of 511 keV photons are observed. The Axial Coordinate in the LYSO bars is reconstructed with a precision of about 1.9 mm (FWHM) using a digital reconstruction method. This resolution is still compromised by the availability of only two WLS strips and will improve with a full stack of LYSO crystals interleaved with WLS strip arrays, which is presently under development for a PET demonstrator set-up.
Rongjing Zhang - One of the best experts on this subject based on the ideXlab platform.
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3D Localization of weak scatterers in Rayleigh-Sommerfeld back-propagation
Optics Express, 2012Co-Authors: Laurence Wilson, Rongjing ZhangAbstract:The Rayleigh-Sommerfeld back-propagation method is a fast and highly flexible volume reconstruction scheme for digital holographic microscopy. We present a new method for 3D localization of weakly scattering objects using this technique. A well-known aspect of classical optics (the Gouy phase shift) can be used to discriminate between objects lying on either side of the holographic image plane. This results in an unambiguous, model-free measurement of the Axial Coordinate of microscopic samples, and is demonstrated both on an individual colloidal sphere, and on a more complex object—a layer of such particles in close contact.
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3D Localization of weak scatterers in digital holographic microscopy using Rayleigh-Sommerfeld back-propagation
Optics Express, 2012Co-Authors: Laurence Wilson, Rongjing ZhangAbstract:The Rayleigh-Sommerfeld back-propagation method is a fast and highly flexible volume reconstruction scheme for digital holographic microscopy. We present a new method for 3D localization of weakly scattering objects using this technique. A well-known aspect of classical optics (the Gouy phase shift) can be used to discriminate between objects lying on either side of the holographic image plane. This results in an unambiguous, model-free measurement of the Axial Coordinate of microscopic samples, and is demonstrated both on an individual colloidal sphere, and on a more complex object — a layer of such particles in close contact.
Annabel Braem - One of the best experts on this subject based on the ideXlab platform.
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wavelength shifter strips and g apd arrays for the read out of the z Coordinate in Axial pet modules
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2008Co-Authors: Annabel Braem, Julien Seguinot, W. Lustermann, D. Schinzel, Eduardo Nappi, Christian Joram, Peter Weilhammer, Enrico Chesi, A. Rudge, I. JohnsonAbstract:Abstract The measurements presented in this paper are related to the development of a PET camera based on a 3-D Axial geometry with excellent 3-D spatial, timing and energy resolution. The detector modules consist of matrices of long Axially oriented scintillation crystal bars, which are individually coupled to photodetectors. The Axial Coordinate is derived from wavelength shifting (WLS) plastic strips orthogonally interleaved between the crystal bars and readout by G-APD arrays. We report on results from measurements with two LYSO crystal bars, read with PMTs, and two WLS strips readout with G-APD devices from Hamamatsu (called MPPC). The WLS strips are positioned orthogonally underneath the LYSO bars. Yields of about 80 photoelectrons from the WLS strips for an energy deposition in the LYSO crystals equivalent to the absorption of 511 keV photons are observed. The Axial Coordinate in the LYSO bars is reconstructed with a precision of about 1.9 mm (FWHM) using a digital reconstruction method. The resolution of an analog Coordinate reconstruction method, which uses the pulse height measurement from the WLS strips is 2.8 mm (FWHM). This resolution is still compromised by the availability of only two WLS strips and will improve with a full stack of LYSO crystals interleaved with WLS strip arrays, which is presently under development for a PET demonstrator set-up.
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A Demonstrator for a new Axial PET Concept
2008 IEEE Nuclear Science Symposium Conference Record, 2008Co-Authors: E. Bolle, Annabel Braem, Enrico Chesi, C. Casella, G. Dissertori, N. Clinthorne, E. Cochran, L. Djambazov, K. Honscheid, I. JohnsonAbstract:In PET imaging, improving sensitivity while maintaining very good spatial resolution is crucial. To achieve this goal, we propose a novel concept of PET scanner, with Axially arranged crystals, providing a high sensitivity and a 3D reconstruction of the gamma interaction point. The trans-Axial Coordinate is given by the crystal hit, while the z Coordinate is reconstructed by the weighted distribution of light escaping the crystal and entering into an array of Wave Length Shifting (WLS) strips interleaving the crystal layers. This novel configuration allows full identification of Compton interactions in the crystals that can be included in image reconstruction thus enhancing the sensitivity. We present preliminary results obtained by a small prototype consisting of 4×4 crystals with orthogonally interleaved WLS strips. Experimental data are compared to simulated data.
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high precision Axial Coordinate readout for an Axial 3 d pet detector module using a wave length shifter strip matrix
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2007Co-Authors: Annabel Braem, Julien Seguinot, W. Lustermann, D. Schinzel, Eduardo Nappi, Christian Joram, Peter Weilhammer, Enrico Chesi, I. Johnson, D RenkerAbstract:We describe a novel method to extract the Axial Coordinate from a matrix of long Axially oriented crystals, which is based on wavelength shifting plastic strips. The method allows building compact 3-D Axial gamma detector modules for PET scanners with excellent 3-dimensional spatial, timing and energy resolution while keeping the number of readout channels reasonably low. A voxel resolution of about 10 mm 3 is expected. We assess the performance of the method in two independent ways, using classical PMTs and G-APDs to read out the LYSO (LSO) scintillation crystals and the wavelength shifting strips. We
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High precision Axial Coordinate readout for an Axial 3-D PET detector module using a wave length shifter strip matrix
Nuclear Instruments and Methods in Physics Research Section A: Accelerators Spectrometers Detectors and Associated Equipment, 2007Co-Authors: Annabel Braem, Julien Seguinot, W. Lustermann, D. Schinzel, R. De Leo, Eduardo Nappi, Christian Joram, Peter Weilhammer, Enrico Chesi, I. JohnsonAbstract:We describe a novel method to extract the Axial Coordinate from a matrix of long Axially oriented crystals, which is based on wavelength shifting (WLS) plastic strips. The method allows building compact 3-D Axial gamma detector modules for PET scanners with excellent 3-D spatial, timing and energy resolution while keeping the number of readout channels reasonably low. A voxel resolution of about 10 mm3is expected. We assess the performance of the method in two independent ways, using classical PMTs and G-APDs to read out the LYSO (LSO) scintillation crystals and the WLS strips. We observe yields in excess of 35 photoelectrons from the strips for a 511 keV gamma and reconstruct the Axial Coordinate with a precision of about 2.5 mm (FWHM). © 2007 Elsevier B.V. All rights reserved.
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Wave length shifter strips and G-APD arrays for the read-out of the z-Coordinate in Axial PET modules
2007 IEEE Nuclear Science Symposium Conference Record, 2007Co-Authors: Annabel Braem, Julien Seguinot, W. Lustermann, D. Schinzel, Eduardo Nappi, Christian Joram, Peter Weilhammer, Enrico Chesi, A. Rudge, I. JohnsonAbstract:The measurements presented in this paper are related to the development of a PET camera based on a 3D Axial geometry with excellent 3-dimensional spatial, timing and energy resolution. The detector modules under development consist of matrices of long Axially oriented scintillation crystal bars, which are individually coupled to photodetectors. The Axial Coordinate is derived from Wave Length Shifting (WLS) plastic strips orthogonally interleaved between the crystal bars and readout by G-APD arrays. We report on results from measurements with two LYSO crystal bars, read with PMTs, and two WLS strips readout with G-APD devices from Hamamatsu (called MPPC). The WLS strips are positioned orthogonally underneath the LYSO bars. Yields of about 80 photoelectrons from the WLS strips for an energy deposition in the LYSO crystals equivalent to the absorption of 511 keV photons are observed. The Axial Coordinate in the LYSO bars is reconstructed with a precision of about 1.9 mm (FWHM) using a digital reconstruction method. This resolution is still compromised by the availability of only two WLS strips and will improve with a full stack of LYSO crystals interleaved with WLS strip arrays, which is presently under development for a PET demonstrator set-up.
Eugene N Nikolaev - One of the best experts on this subject based on the ideXlab platform.
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fourier transform ion cyclotron resonance cell with dynamic harmonization of the electric field in the whole volume by shaping of the excitation and detection electrode assembly
Rapid Communications in Mass Spectrometry, 2011Co-Authors: Ivan Boldin, Eugene N NikolaevAbstract:A new principle of formation of the effective electric field distribution in a Penning trap is presented. It is based on the concept of electric potential space averaging via charged particle cyclotron motion. The method of making hyperbolic-type field distribution in the whole volume of a cylindrical Penning trap is developed on the basis of this new principal. The method is based on subdividing the cell cylindrical surface into segments with shapes producing quadratic dependence on Axial Coordinate of an averaged (along cyclotron motion orbit) electric potential at any radius of cyclotron motion. The cell performance is compared in digital experiments with the performance of a Gabrielse-type cylindrical cell with four compensation electrodes and is shown to be more effective in ion motion harmonization at higher cyclotron radii and Axial oscillation amplitude. Copyright © 2010 John Wiley & Sons, Ltd.
Dorin Ieşan - One of the best experts on this subject based on the ideXlab platform.
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Deformation of chiral rods in the strain gradient theory of thermoelasticity
European Journal of Mechanics A-solids, 2012Co-Authors: Dorin IeşanAbstract:Abstract We study the deformation of a chiral cylinder subjected to a prescribed thermal field in the context of the linear theory of gradient thermoelasticity. First, we investigate the effects of a thermal field which is independent of the Axial Coordinate. It is shown that the temperature variation produces extension, bending, torsion and a plane deformation. Then, we study the deformation of the rod when the thermal field is a polynomial of degree m in the Axial Coordinate. The solution is reduced to the solving of some two-dimensional problems. The method is used to solve the problem of a circular cylinder subjected to a uniform temperature field. In contrast with the case of achiral materials, a constant thermal field in an isotropic chiral cylinder produces torsional effects.
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Thermal Stresses in Chiral Elastic Beams
Journal of Thermal Stresses, 2011Co-Authors: Dorin IeşanAbstract:The chiral effects cannot be described by means of the classical thermoelasticity. In the context of the linear theory of Cosserat thermoelasticity we study the deformation of a chiral beam subjected to a prescribed thermal field. This paper points out the importance of the generalized plane strain problem in the analysis of thermal stresses in chiral elastic beams. First, we investigate the effects of a thermal field which is linear in the Axial Coordinate. It is shown that this temperature variation produces extension, bending, torsion, flexure and a plane deformation. Then, we study the deformation of the beam when the thermal field is a polynomial of degree m (m > 1) in the Axial Coordinate. The solution is reduced to the solving of some two-dimensional problems. The method is used to solve the problem of a circular cylinder subjected to a temperature that is independent of the Axial Coordinate.
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Deformation of porous Cosserat elastic bars
International Journal of Solids and Structures, 2011Co-Authors: Dorin IeşanAbstract:This paper is concerned with the linear theory of porous Cosserat elastic solids. We study the equilibrium of a cylindrical bar which is subjected to resultant forces and resultant moments on the ends, to body loads and to surface tractions on the lateral surface. The Almansi problem, where the body loads and the surface loading on the lateral surface are polynomials in the Axial Coordinate, is considered. The bar is made of an inhomogeneous and isotropic material whose constitutive coefficients are independent of the Axial Coordinate. The problem is reduced to the study of two-dimensional problems. The results are used to study two practical applications concerning the deformation of a circular rod. It is shown that a uniform pressure on the lateral surface produces an extension, a uniform change of the porosity, and a plane deformation. The bending by terminal couples produces a non-uniform variation of the porosity and a microrotation of the material particles.
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THERMAL STRESSES IN HETEROGENEOUS ANISOTROPIC COSSERAT ELASTIC CYLINDERS
Journal of Thermal Stresses, 2007Co-Authors: Dorin IeşanAbstract:Abstract A method of solving the problem of thermal stresses for composite cylinders, where the cross section is occupied by different inhomogeneous and anisotropic Cosserat elastic materials is established. The temperature variation is assumed to be a polynomial in the Axial Coordinate. The method is used to study the deformation of a circular cylinder composite of two different isotropic materials.
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On the theory of loaded inhomogeneous cylinders
Mechanics Research Communications, 2007Co-Authors: Dorin Ieşan, L. NappaAbstract:Abstract This article is concerned with the relaxed Saint-Venant’s problem in the case when the body forces and surface tractions on the lateral surface are polynomials in the Axial Coordinate. A new method of solving this problem is presented. The method is applied to study the problem of a uniformly loaded cylinder.
