Bibliografías temáticas / Neutron absorption

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Literatura académica sobre el tema "Neutron absorption"

Autor: Grafiati
Publicado: 30 de noviembre de 2024

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Artículos de revistas sobre el tema "Neutron absorption"

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Wang, Haoran, Shuo Zhao, Junqing Han, Yuying Wu, Xiangfa Liu y Zuoshan Wei. "Neutron-Absorption Properties of B/Cu Composites". Materials 16, n.º 4 (8 de febrero de 2023): 1443. http://dx.doi.org/10.3390/ma16041443.

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Copper has high electrical and thermal conductivity, which is frequently employed in structural and functional materials. In this research, powder metallurgy was used to incorporate boron nanosheets into metal matrix composites to create boron dispersion-enhanced copper matrix composites. The neutron-absorption characteristics of composite materials were investigated, as well as the link between neutron-absorption cross-section and neutron energy. The results told us that the morphology of the second phase on the particle surface is closely related to the size of Cu-B particles, copper and boron correspond atomically to each other on the interface without dislocation or lattice distortion, forming a completely coherent interface, and that the neutron absorption cross-section decreases exponentially as neutron energy increases. In low-energy neutrons with energies less than 0.1 eV, the increase of boron content and 10B abundance in Cu-B alloy will enhance the neutron-absorption capacity of the alloy. Boron dispersion-strengthened copper matrix composites have good neutron-absorption capacity, and the microstructure and size of boron do not affect the neutron-absorption performance of composites with the same content of boron. The hardness of the B-dispersion-strengthened Cu matrix composite obtained by nanoindentation test is about 3.04 GPa. Copper matrix composites with boron dispersion reinforcement exhibit high hardness and neutron-absorption characteristics.
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Selke, David L. "Physics Essay: Repulsionless Fusion by Neutron Absorption". Applied Physics Research 8, n.º 6 (17 de noviembre de 2016): 30. http://dx.doi.org/10.5539/apr.v8n6p30.

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<p class="1Body">It is possible to build Helium-4 from Hydrogen-1 by adding only neutrons. The key step is that Tritium decays to Helium-3; thus, a particle that entered the nucleus as a neutron becomes a proton. The need to overcome the mutual repulsion of positively charged nuclei is thus avoided. Given a cheap enough neutron source, this method promises fusion without Sun-like conditions.</p>
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Mahdavi, Mohammad y Maryam Shahbahrami. "Multiplication of Fast Neutrons Source Flux by Using Deuterium-Helium-3 Plasma". ISRN High Energy Physics 2013 (30 de mayo de 2013): 1–4. http://dx.doi.org/10.1155/2013/689739.

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The production of fast neutrons source is examined by using a thermal neutron flux inside plasma. In order to reach a favorable yield of fast neutrons flux, the parameters such as energy loss rate, reaction probability, and neutron absorption length are calculated. The nuclear conversion efficiency, , of thermal neutron to fast neutrons is obtained to be by calculating the physical parameters for the plasma designed.
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Volz, Heather M., Sven C. Vogel, J. A. Roberts, A. C. Lawson, D. J. Williams y L. L. Daemen. "Effect of Strong Neutron Absorption on Texture and Diffraction Data Analysis". Materials Science Forum 495-497 (septiembre de 2005): 119–24. http://dx.doi.org/10.4028/www.scientific.net/msf.495-497.119.

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The impact of strong neutron absorption on data analysis and the comparison of two different absorption corrections for neutron diffraction data implemented in the GSAS Rietveld code are the foci of this work. We investigated the effect of absorption on the texture and the thermal motion parameter for rolled elemental foils. The orientation distribution functions (ODF) of rolled foils of dysprosium and erbium metals were determined from neutron time-of-flight data patterns collected on HIPPO at LANSCE. Both Dy and Er are strong absorbers for thermal neutrons with absorption cross-sections of 994 barns for Dy and 159 barns for Er at l = 1.8 Å. Various stacks of foils of each material, along with combinations of absorbing and less-absorbing foils, were measured. The patterns were analyzed using the GSAS options for Debye-Scherrer and linear absorption models, as well as without an absorption correction. Discrepancies between refined and expected “true” values of crystallographic parameters if absorption is not taken into consideration are discussed.
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Mildner, D. F. R., H. Chen, R. G. Downing y V. A. Sharov. "Developing a focused neutron probe for materials analysis". Proceedings, annual meeting, Electron Microscopy Society of America 50, n.º 2 (agosto de 1992): 1728–29. http://dx.doi.org/10.1017/s0424820100133278.

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Long wavelength neutrons have optical properties analogous to those of photons, and may be focused to produce significantly higher fluxes using the principle of multiple mirror reflection from smooth surfaces at small grazing incident angles. Narrowly focused beams of cold neutrons (with wavelengths greater than 0.4 nm) allow greater spatial resolution for analytical applications than previously available, and will improve the detection limits of neutron absorption measurements (which are dependent on the neutron capture reaction rate) for quantitative analysis. Since the absorption cross section increases linearly with neutron wavelength, the reaction rate for a given isotope increases with the use of cold neutrons. This suggests microprobe capabilities which complement other radiation techniques for multidimensional microanalysis of trace elements in materials science. Among the techniques which will benefit by the development of focused neutrons are prompt gamma activation analysis and neutron depth profiling, by increasing the elemental sensitivity, lowering the detection limits, enhancing multi elemental as well as spatial analysis.
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Piscitelli, F., A. Khaplanov, A. Devishvili, S. Schmidt, C. Höglund, J. Birch, A. J. C. Dennison, P. Gutfreund, R. Hall-Wilton y P. Van Esch. "Neutron reflectometry on highly absorbing films and its application to 10 B 4 C-based neutron detectors". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, n.º 2185 (enero de 2016): 20150711. http://dx.doi.org/10.1098/rspa.2015.0711.

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Neutron reflectometry is a powerful tool used for studies of surfaces and interfaces. The absorption in the typical studied materials is neglected and this technique is limited only to the reflectivity measurement. For strongly absorbing nuclei, the absorption can be directly measured by using the neutron-induced fluorescence technique which exploits the prompt particle emission of absorbing isotopes. This technique is emerging from soft matter and biology where highly absorbing nuclei, in very small quantities, are used as a label for buried layers. Nowadays, the importance of absorbing layers is rapidly increasing, partially because of their application in neutron detection; a field that has become more active also due to the 3 He -shortage. We extend the neutron-induced fluorescence technique to the study of layers of highly absorbing materials, in particular 10 B 4 C. The theory of neutron reflectometry is a commonly studied topic; however, when a strong absorption is present the subtle relationship between the reflection and the absorption of neutrons is not widely known. The theory for a general stack of absorbing layers has been developed and compared to measurements. We also report on the requirements that a 10 B 4 C layer must fulfil in order to be employed as a converter in neutron detection.
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Chen, Junyang, Ulrich Rücker, Jörg Voigt, Paul Zakalek, Egor Vezhlev, Jingjing Li, Thomas Gutberlet y Thomas Brückel. "Thermal moderator-reflector design of the 24 Hz target station for the High Brilliance Neutron Source". EPJ Web of Conferences 286 (2023): 02005. http://dx.doi.org/10.1051/epjconf/202328602005.

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The High Brilliance Neutron Source (HBS) project develops a high current accelerator driven neutron source (HiCANS), aiming to substitute existing neutron research reactors, that reach the end of life. This study focuses on the thermal neutron moderator design for a low frequency, long pulse target station of HBS. We investigate the neutronic characteristics of the D2O+H2O mixture moderator material using the Monte Carlo particle transport code PHITS. Our findings show that, compared to D2O with lower neutron absorption, confinement of H2O is the dominant factor in achieving a high neutron flux within the moderator and thus a high neutron brightness. We find that surrounding the central thermal water moderator with a D2O+H2O mixture can achieve a better balance between confinement and absorption. However, because of multiple angles of reflecting neutron, this design will also increase the divergence of the neutron beam.
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8

Shishido, Hiroaki, The Dang Vu, Kazuya Aizawa, Kenji M. Kojima, Tomio Koyama, Kenichi Oikawa, Masahide Harada et al. "Crystalline Orientation of CaF2 window determined by Neutron Transmission Imaging using a Delay Line Current-Biased Kinetic-Inductance Detector". Journal of Physics: Conference Series 2545, n.º 1 (1 de julio de 2023): 012020. http://dx.doi.org/10.1088/1742-6596/2545/1/012020.

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Abstract The combination of a high speed two-dimensional neutron detector and an intensive pulsed neutron source provides not only neutron transmission imaging but also information on crystal structures, orientations and constituent elements by analyzing neutron transmission spectra. The delay-line current-biased kinetic-inductance detector (CB-KID) is a two-dimensional superconducting neutron detector with high spatial and temporal resolutions, and multi-hit tolerance. We demonstrated that the delay-line CB-KID with a 10B neutron conversion layer can be applied for neutron transmission measurements up to 100 keV. We observed two-different dip structures in the transmission spectra in a CaF2 single crystal, i.e., one is from the Bragg diffraction and the other is from nuclear resonance absorption. We consider that some duplicated structures in resonance absorption dips are originating from a double-bunch structure of proton pulses for producing pulsed neutrons in the accelerator.
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Ekhwan Razali, Mohd, Roszilah Hamid y Yusof Abdullah. "Mechanical Properties and Thermal Neutron Absorption of Heavyweight Hematite Aggregate Concrete for Radiation Shielding". International Journal of Engineering & Technology 8, n.º 1.2 (30 de enero de 2019): 123–30. http://dx.doi.org/10.14419/ijet.v8i1.2.24883.

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Heavyweight aggregate concrete (HWAC) is the most widely used material as radiation shielding for nuclear reactors. The density of HWAC is increased through the use of heavy natural aggregates such as barites, hematite and magnetite. This study determines the density of HWAC with hematite aggregate replacing granite at 0%, 10%, 20%, 30%, 40% and 50%, its compressive strength and thermal neutron absorption of 1 MeV fast neutrons. The physical properties of hematite which include gradation, specific gravity, water absorption and loose unit weight are determined. The chemical composition of hematite is also determined using X-ray fluorescent (XRF) analysis. The slump, density, compressive strength and thermal neutron absorption of the heavyweight concrete containing different proportion of hematite as aggregate are also determined. Results show that the slumps of HWAC are between 77 mm – 84 mm, the density of HWAC increases between 0.3% - 1.18% by increasing the hematite content. HWAC with 10% hematite exhibits highest strength at 52.5 MPa and the highest thermal neutron absorption at 2085 count per second. The optimum amount of hematite to replace granite for best strength and neutron absorption is 10%.Â
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Laureau, Axel, Max Begue, Vincent Lamirand, Elsa Merle y Oskari Pakari. "Fast simulation of neutron noise using the Transient Fission Matrix approach and validation on the CROCUS reactor". EPJ Web of Conferences 302 (2024): 08002. http://dx.doi.org/10.1051/epjconf/202430208002.

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This article presents the development of a neutron noise calculation technique with a reduced calculation time based on the TFM (Transient Fission Matrix) approach. The latter contains different information such as the system transfer function (fission and absorption probability density functions and corresponding neutron multiplicity) of prompt and delayed neutrons, and the corresponding propagation time. This information is used to reconstruct neutron showers based on precursor decays up to the shower disappearance by absorption, leakage or delayed neutron precursor creation. Then pseudo-detectors such as fission chamber count rate histograms are reconstructed from these neutron showers and the αprompt is calculated from the cross-correlation function. A very good agreement has been obtained on the uranium-fueled light water reactor CROCUS between the model developed and the reference value.
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Tesis sobre el tema "Neutron absorption"

1

Paoli, M. P. "Electron-volt neutron spectroscopy of condensed matter". Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235080.

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MOREIRA, EDSON G. "Preparo e caracterizacao de um material de referencia de mexiliao Perna perna (Linnaeus, 1758)". reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9529.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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3

Schollier, Audrey. "Probing protein adsorption modes onto poly(ethylene glycol) brushes by neutron reflection". Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209952.

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Adsorption of proteins at interfaces has an important role in biotechnological and pharmaceutical applications. Indeed, several undesirable processes are related to protein adsorption, as for example: fouling of contact lenses, clotting on blood contacting devices, triggering inflammation around artificial organs, diminished circulation time of therapeutic proteins and drug bearing liposomes. Neutral water soluble polymers, such as poly(ethylene glycol) (PEG), are used to repress protein adsorption: by coating the surface with a polymer brush, a "cushion" is created between the protein and the surface, that can reduce, or even completely repress the adsorption. Understanding the mechanism that inhibits the adsorption at interfaces is an active field of research, and could lead to relevant improvements in biomaterials performances and design.

A clear understanding of the mechanism of protein adsorption onto polymer brushes is still missing. The first models describing the interactions of a polymer brush with adsorbing particles predicted two adsorption modes: primary adsorption at the grafting surface, and secondary adsorption at the outer edge of the brush (occurring for large cylindrical proteins). Primary adsorption can be repressed by increasing the grafting density of the brush, and secondary adsorption by increasing its thickness, in agreement with the experiments reported in the literature. But experimental evidences (a maximum in the adsorbed amount observed for long brushes) suggested then the existence of a third mode: ternary adsorption within the brush itself, due to attractive interactions between the protein and the brush. Standard techniques can in general only probe the total adsorbed amount. The aim of this work was to separate primary and ternary adsorption isotherms, by using neutron reflectivity and deuterated proteins. As neutrons interact differently with hydrogen and deuterium atoms, the contrast between the hydrogenated brush and the deuterated protein is high enough to separate the two contributions.

We studied the adsorption of deuterated myoglobin on PEG brushes with different degrees of polymerisation (N = 56, 146 and 770), and as a function of the area per grafted chain. The contribution of primary and ternary adsorption was separated for the different systems, and the adsorbed amount was extracted and the adsorption isotherms compared to the theoretical predictions. The ability to distinguish between the different adsorption modes, and the quantification of their relative contribution to the overall amount of adsorbed proteins, represents a major advance in optimising surface properties. In particular, the occurrence of ternary adsorption onto PEG brushes affects their status as tool for repressing protein adsorption.

L’adsorption de protéines aux interfaces a un rôle important pour certaines applications pharmaceutiques ou biotechnologiques. En effet, plusieurs processus indésirables sont liés à l’adsorption de protéines, par exemple l’encrassement de lentilles de contact, la coagulation dans des appareils contenant du sang, l’inflammation d’organes artificiels ou encore la diminution du temps de circulation dans le corps de protéines ou liposomes thérapeutiques. Certains polymères, tels que le polyéthylène glycol (PEG), sont utilisés pour réprimer l’adsorption de protéines :en greffant une brosse de PEG sur la surface, une couche est créée entre la protéine et celle-ci qui diminue, voire même réprime complètement l’adsorption. Comprendre le mécanisme qui entrave l’adsorption aux interfaces est un sujet de recherche actif, qui pourrait mener à des améliorations significatives dans la conception de biomatériaux.

À ce jour, la compréhension du mécanisme d’adsorption de protéines sur des brosses de polymère n’est pas claire. Les premiers modèles décrivant les interactions entre brosses de polymères et particules adsorbantes prédisaient deux modes d’adsorption :l’adsorption primaire sur la surface de greffage, et l’adsorption secondaire à l’extérieur de la brosse (pour les grandes protéines cylindriques uniquement). L’adsorption primaire peut-être réprimée en augmentant la densité de greffage de la brosse, et l’adsorption secondaire en augmentant son épaisseur, en accord avec les expériences reportées dans la littérature. Mais d’autres évidences expérimentales (un maximum dans la quantité adsorbée observé pour les brosses longues) ont ensuite suggéré l’existence d’un troisième mode :l’adsorption ternaire à l’intérieur même de la brosse, due aux interactions attractives entre la protéine et la brosse.

Les techniques standards peuvent en général mesurer la quantité adsorbée totale. Le but de ce travail était de séparer les isothermes d’adsorption primaire et ternaire, en utilisant la réflectivité de neutrons et des protéines deutérées. Comme les neutrons interagissent différemment avec les atomes d’hydrogène ou de deutérium, le contraste entre la brosse hydrogénée et la protéine deutérée est ainsi suffisant pour séparer les deux contributions.

Nous avons étudié l’adsorption de myoglobine deutérée sur des brosses de PEG avec différents degrés de polymérisation (N = 56, 146 and 770), en fonction de l’aire par chaîne Σ. La contribution des adsorptions primaire et ternaire put être séparée pour les différents systèmes, et les quantités adsorbées extraites pour finalement comparer les isothermes d’adsorption aux prédictions théoriques. La possibilité de distinguer les différents modes d’adsorption, et la quantification de leur contribution relative à la quantité totale de protéines adsorbées représente une avancée majeure dans l’optimisation des propriétés des surfaces. L’adsorption ternaire dans les brosses de PEG en particulier remet en question leur utilisation pour réprimer l’adsorption de protéines.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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CURCHO, MICHEL R. da S. M. "Avaliacao de micro e macroelementos, elementos toxicos (Cd, Hg e Pb) e acidos graxos, em peixes disponiveis comercialmente para consumo em Cananeia e Cubatao, Estado de Sao Paulo". reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9388.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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5

Pavan, Lucia. "Study of external fields around magnetars and analysis of interstellar absorption". Doctoral thesis, Università degli studi di Padova, 2009. http://hdl.handle.net/11577/3425614.

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This thesis describes mainly two topics: the analysis of the external field of hyper-magnetized neutron stars (magnetars), and the distribution of galactic interstellar absorption. Magnetars have been introduced as a theoretical model to account for the peculiar characteristics of a limited group (~15 objects out of more than two thousands known) of isolated neutron stars. Though being so few, these objects are extensively studied due to their extreme properties. In the magnetar model, the emission of such sources is explained as energy released from the magnetic field (hence the name) rather than from rotational, gravitational or thermal energy as for the majority of the neutron stars. From measures of spin periods and their variations, the magnetic fields involved are estimate to be of order 10^14-10^15 G (10^10-10^11 T), making these stars the ’strongest magnets’ of the Universe. In this frame the study of magnetars opens the possibility to analyze the effects of the magnetic fields on plasma under really extreme conditions. The magnetic fields we deal with exceed the quantum threshold B_QED~ 4·10^13 G (4·10^9 T) and cause strong alterations of the properties of matter (for a review see Harding & Lai [60]). Not only such an intense field strongly interacts with the plasma and modify the atomic structure of matter, but it also modifies the properties of vacuum too. One of the more noticeable effectsis the vacuum polarization that alters the propagation of photons introducing ordinary and extraordinary modes. The only tool to study these objects is the analysis of their emitted radiation. This is the reason why a great effort has been devoted to synthetically model the spectra of magnetars. The aim of these studies is to take into account the known effects of the field and indirectly derive, from the collected spectra, some constraint on the physical conditions in the emitting zones, both on the star surface and in the magnetosphere. The magnetar model has been developed in different works, starting in 1992 with the one of Thompson and Duncan. In 2002, in a paper by Thompson, Lyutikov and Kulkarni, the external field of magnetars was described as a sheared dipole. In this model the torsion comes from the interior and gradually twist the crust, shearing, as a consequence, the external field too. The bursts are fueled by a sudden release of great amount of energy due to fractures of the crust occurring as the stress imparted from the field become too strong. Assuming this configuration of the field, the magnetar model is able to reproduce the spectral behaviour of the majority of the Anomalous X-Ray Pulsars and Soft Gamma Repeaters. Surprisingly, the magnetar model also suggested a link between these two classes that had become clearer only when a number of sources with intermediate properties between the two has been discovered. Nevertheless, as more studies are conducted on magnetar spectra, the underlying model need to be refined. Some recent works suggest, for example, small emitting zones that do not cover the entire star, or the presence of different temperatures on the surface of the magnetars. In some cases there are indications that the twist may be confined only to a portion of the magnetosphere, and/or that the large scale field is more complex than a simple dipole. The studies conducted in this work follow this researchline, and are intended to extend the preexisting model. The followed idea is to include field variations on small scales, achieved considering multipolar fields of various orders. The other subject of this work deals with interstellar absorption in our Galaxy. Interstellar extinction is the subject of many studies, as it modifies the radiation emitted by all the sources. As the dust and the interstellar particles are not emitting (with the exception of the infrared emission from silicates and polycyclic aromatic hydrocarbon (PAH) molecules), they are particularly difficult to analyze. Generally the interstellar absorbing medium is visible only when illuminated from starlight; therefore, when possible, it is directly measured by the collected radiation, both analyzing low-ionization lines in spectra, and from photometric analysis. These methods, though, give a measure of extinction only for a number of objects and cannot cover extensively the observed sky. To obtain a value for the extinction towards directions for which there are no available measures, it is common to use a model of the distribution of dust in the Galaxy. While the advantages of an extinction models are evident, as they allow to infer absorption quantities even where there is a lack of measures, the disadvantage is the need to make assumptions on the stellar and/or dust components of the Galaxy. This introduces again other uncertainties on the final result. A different approach is based on the analysis of the dust infrared emission (Schlegel, Finkbeiner & Davis [107]) in order to map the interstellar medium. Unfortunately even this method has limitations, as it gives informations only on the total column density in each direction, without the possibility to resolve the three dimensional structure of the distribution of interstellar medium. In this context the work performed in this thesis aims at constructing an algorithm to interpolate the extinction measures available in literature, without recurring to a model of the Milky Way components. The idea followed is to collect the greater possible set of absorption data, in order to create a coarse-grained three dimensional map of the galactic extinction, and interpolate these data to infer the values between the known points. As extinction is a cumulative measure of the absorption occurring between the observer and the star, before interpolating the data, a deconvolution of these measured quantities into local values of absorption, is needed. Some preliminary results obtained with the developed code and conclusions are drawn.
Gli argomenti trattati nella presente tesi sono due: l’ analisi del campo attorno a stelle di neutroni iper-magnetizzate (Magnetar) e la distribuzione dell’ assorbimento interstellare nella nostra Galassia. Le Magnetar sono state introdotte come modello teorico per spiegare le caratteristiche peculiari di un ristretto sottoinsieme di stelle di neutroni isolate, circa 15 oggetti su più di 2000 noti. Nonostante siano così pochi, questi oggetti sono argomento di numerosi studi a causa delle loro proprietà estreme. All’interno del modello di magnetar, l’emissione di queste sorgenti viene spiegata come energia rilasciata dal campo magnetico (da cui il nome) piuttosto che da riserve di energia rotazionale, gravitazionale o termica come avviene per la maggior parte delle stelle di neutroni. Dalle misure dei periodi orbitali e dalla loro variazione nel tempo, i campi magnetici coinvolti sono stimati essere dell’ordine di 10^14-10^15 G (10^10-10^11 T), portando queste stelle ad essere “i magneti più intensi” dell’Universo. In questo quadro, lo studio delle magnetars apre la possibilità di analizzare gli effetti di campi magnetici su plasmi in condizioni davvero estreme. I campi magnetici che vengono trattati superano la soglia B_QED~ 4·10^13 G (4·10^9 T) e quindi provocano grandi alterazioni delle proprietà intrinseche della materia (per una review si veda Harding & Lai [60]). Campi così intensi non solo interagiscono pesantemente col plasma modificando la struttura atomica della materia, ma alterano anche le proprietà del vuoto. Uno degli aspetti più significativi è la polarizzazione del vuoto che introduce i modi ordinario e straordinario di propagazione dei fotoni. L’unico strumento per studiare questi oggetti è l’analisi della radiazione emessa; questo è il motivo per cui sono stati compiuti grandi sforzi per creare modelli sintetici di spettri delle magnetars. Lo scopo di queste ricerche è di derivare, indirettamente dagli spettri raccolti, alcuni vincoli sulle condizioni fisiche delle zone emittenti, sia sulla superficie della stella che nella magnetosfera. Il modello è stato sviluppato in vari articoli a partire dal 1992 con il lavoro di Thompson e Duncan. Nel 2002, in un articolo di Thompson, Lyutikov e Kulkarni, il campo esterno delle magnetars è stato descritto come un dipolo twistato attorno al proprio asse magnetico. In questo modello una torsione si propaga dalle zone interne e gradualmente deforma la crosta, provocando una distorsione anche nel campo esterno. I burst osservati sarebbero quindi alimentati dall’improvviso rilascio di una grande quantità di energia dovuta a fratture della crosta, che avvengono quando lo stress sulla superficie diventa troppo forte. Assumendo questa con?gurazione del campo, il modello è in grado di riprodurre le caratteristiche spettroscopiche della maggior parte delle Anomalous X-Ray Pulsars e dei Soft Gamma Repeaters. Sorprendenetemente il modello delle magnetar suggeriva anche un legame tra queste due classi di oggetti, che è stato confermato in seguito, dalla scoperta di oggetti con proprietà intermedie tra le due classi. Ciò nonostante, a mano a mano che nuovi studi vengono condotti sull’emissione delle magnetar, il modello necessità di essere affinato. Alcuni lavori recenti, ad esempio, suggeriscono o che le zone emittenti siano piccole e non coprano l’intera superficie della stella, oppure che siano presenti zone a diversa temperatura sulla superficie. In alcuni casi, il twist sembra essere confinato solo a delle porzioni della magnetosfera e/o il campo, su larga scala, sembra essere più complesso di un semplice dipolo. Gli studi condotti si inseriscono in questo quadro e sono rivolti a generalizzare il modello esistente. L’idea che è stata seguita è quella di includere delle variazioni del campo su piccola scala considerando multipoli di ordini diversi. A differenza di quanto accade per campi generici, in questo caso il procedimento è complicato della non linearità delle equazioni che descrivono i campi twistati. Il secondo argomento di questa tesi riguarda l’assorbimento interstellare nella nostra Galassia. L’estinzione interstellare è oggetto di molti studi in quanto modifica la radiazione osservata proveniente dalle sorgenti celesti. Le polveri e le particelle interstellari non emettono radiazione, ad eccezione dell’emissione infrarossa, dovuta a silicati e idrocarburi policiclici aromatici, e dunque sono molto difficili da analizzare. Generalmente, il mezzo interstellare è visibile solo quando viene illuminato da altre sorgenti, quindi, ove possibile, viene misurato direttamente dalla radiazione emessa da oggetti lontani ed osservata sia analizzando righe spettroscopiche di bassa ionizzazione che da analisi fotometriche. Questi metodi tuttavia, forniscono una misura dell’estinzione solo tra l’ osservatore e alcuni oggetti, ma non coprono estensivamente tutto il cielo. Per ottenere misure di estinzione laddove le misure non sono presenti, generalmente viene impiegato un modello di distribuzione delle polveri nella Galassia. Mentre i vantaggi riguardanti l’uso dei modelli di estinzione sono evidenti, dato che permettono di ricavare la quantità di estinzione anche in zone dove le misure sono assenti, lo svantaggio è dovuto alla necessità di adottare delle assunzioni sulle proprietà delle stelle e/o sulle polveri della Galassia, che introducono ulteriori incertezze nel risultato finale. Un approccio differente è basato sull’analisi dell’emissione infrarossa delle polveri (Schlegel, Finkbeiner & Davis [107]) per mappare il mezzo interstellare. Purtroppo anche questo metodo ha delle limitazioni, in quanto fornisce informazioni solo sull’intera column density in una determinata direzione, senza la possibilità di risolvere la struttura tridimensionale della distribuzione del mezzo interstellare. In questo contesto il presente lavoro è rivolto alla realizzazione di un algoritmo utile ad interpolare le misure di estinzione disponibili in letteratura, senza dover ricorrere ad un modello per le componenti della Via Lattea. L’idea che è stata seguita è quella di raccogliere la maggior quantità possibile di dati di assorbimento, al fine di ottenere una mappa tridimensionale (seppur grossolana) dell’estinzione nella nostra Galassia, e interpolare questi dati per ricavare il valore di assorbimento in posizioni diverse da quelle già note. Poiché l’ estinzione è una misura cumulativa dell’assorbimento distribuito tra l’osservatore e la stella, prima di interpolare i dati è necessario effettuare fare una scomposizione degli assorbimenti misurati in valori locali di assorbimento. Le conclusioni e alcuni risultati preliminari del codice che è stato sviluppato sono presentati.
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BOSTELMANN, ELEINE. "Avaliação da concentração de metais em amostras de sedimentos do reservatório Billings, Braço do Rio Grande, São Paulo, Brasil". reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11410.

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Swansbury, Laura Ann. "A structural investigation of chlorine-containing and fluorine-containing oxide glasses using molecular dynamics, neutron diffraction, and X-ray absorption spectroscopy". Thesis, University of Kent, 2017. https://kar.kent.ac.uk/65765/.

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Scientific developments have enabled glasses to fulfil an array of applications, from windows to bioactive glasses in regenerative medicine. To further exploit the capability of this versatile material, it is imperative that their structure is understood. In this thesis, the structure of three glass systems containing halides as anions were investigated. The first of these was the intermediate glass former ZnCl2 which was modelled computationally using classical molecular dynamics (MD). The addition of the adiabatic core-shell model was able to account for anion polarisability. This enabled the first fully tetrahedral model of ZnCl2 glass to be attained. While 86% of the ZnCl4 tetrahedral units were corner-sharing, 14% were found to be edge-sharing. The calculated total neutron and x-ray structure factors closely replicated those obtained experimentally in other works. The intermediate glass former ZnCl2 was later compared to the strong glass former SiO2. The main contribution in the first sharp diffraction peaks came from the cation-anion contribution, rather than the cation-cation contribution as previously reported. Next to be investigated was a CaO-SiO2-CaCl2 glass series. This was to help elucidate the structure of more complex CaO-SiO2-P2O5-CaCl2 chlorine-containing bioactive glass compositions. A glass series was synthesised by collaborators, and compositional analysis in this work revealed that chlorine losses via chlorine volatilisation occurred as HCl. The glass series was studied experimentally using neutron diffraction (ND) and x-ray absorption spectroscopy (XAS) at the Ca and Cl K-edge. By probing the calcium environment using ND and XAS, generally good agreement between the Ca-O and Ca-Cl coordination numbers was achieved. The total correlation functions from neutron diffraction did not exhibit a noticeable contribution around 2.1Å which would have been expected for Si-Cl bonding. Computational modelling was performed using MD with the addition of the adiabatic core-shell model. No Si-Cl bonding was observed, and the calculated total neutron structure factors closely resembled those obtained experimentally. The glass models were found to become phase separated with increasing CaCl2 content to form a biphasic system of calcium silicate and calcium chloride phases. Interestingly, there was a tendency towards phase separation even in glass models containing small amounts of CaCl2. The remaining glass system, CaO-SiO2-CaF2, was studied to help elucidate the structure of more complex CaO-SiO2-P2O5-CaF2 fluorine-containing bioactive glasses. Following the synthesis of the CaO-SiO2-CaF2 glass series, compositional analysis revealed that fluorine losses due to fluorine volatilisation occurred as HF. The calcium environment of the glasses was probed using ND and XAS at the Ca K-edge. Distinguishing the overlapping Ca-F and Ca-O paths around 2.3Å and 2.4Å respectively was challenging. The glass series was modelled computationally using MD with the addition of the adiabatic core-shell model. The calculated total neutron structure factors closely replicated those from experiment. The glass models also revealed that while fluorine ions overwhelmingly bond with calcium ions, small amounts of Si-F bonding are observed which conceivably cannot be resolved experimentally.
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Buchanan, Piers. "The structure of liquid semiconductors, superionic conductors and glasses by neutron scattering, X-ray diffraction and extended X-ray absorption fine structure". Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392943.

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Černý, Tomáš. "Stínění a detekce neutronů". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413124.

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The master’s thesis provides an overview of available neutron sources in terms of neutron yields and energy spectrum of emitted neutrons. Reactions of neutrons with matter, especially neutron scattering and radiation capture, are described. The possibilities neutron neutron detection and spectrometry are also described. The following experiment deals with a design of suitable shielding materials and the analysis of the moderated energy spectrum of neutron flux. The properties of the neutron field were measured using detection by activation. Subsequently, a simulation of the problem was performer in the MCNP program. In the end, the achieved results are compared and evaluated.
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ARINE, DJAIR R. "Analise de aguas de superficie e sedimentos de rios da regiao de Ipero, SP, por espectrometria de absorcao atomica e por ativacao neutronica". reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10831.

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Libros sobre el tema "Neutron absorption"

1

Tripathi, Ram K. New parameterization of neutron absorption cross sections. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1997.

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Tripathi, Ram K. New parameterization of neutron absorption cross sections. Washington, D.C: National Aeronautics and Space Administration, 1997.

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Wilson, John W. Nucleon-nucleus interaction data base: Total nuclear and absorption cross sections. Hampton, Va: Langley Research Center, 1988.

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United States. National Aeronautics and Space Administration., ed. High-energy astrophysics: A theoretical analysis of thermal radiation from neutron stars : annual status report for NAGW-3075. [Washington, DC: National Aeronautics and Space Administration, 1994.

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United States. National Aeronautics and Space Administration., ed. High-energy astrophysics: A theoretical analysis of thermal radiation from neutron stars : annual status report for NAGW-3075. [Washington, DC: National Aeronautics and Space Administration, 1994.

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Tripathi, Ram K. Universal parameterization of absorption cross sections. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1997.

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W, Townsend Lawrence, Wilson J. W y United States. National Aeronautics and Space Administration. Scientific and Technical Information Program., eds. Target correlation effects on neutron-nucleus total, absorption, and abrasion cross sections. [Washington, DC]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1991.

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Tripathi, Ram K. Universal parameterization of absorption cross sections: Light systems. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1999.

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F, Hepp Aloysius y United States. National Aeronautics and Space Administration., eds. Near-edge study of gold-substituted YBa₂Cu₃O₇₋(delta). [Washington, DC]: NASA, 1991.

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F, Hepp Aloysius y United States. National Aeronautics and Space Administration., eds. Near-edge study of gold-substituted YBa₂Cu₃O₇₋(delta). [Washington, DC]: NASA, 1991.

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Capítulos de libros sobre el tema "Neutron absorption"

1

Swinhoe, M. T., J. D. Hutchinson y P. M. Rinard. "Neutron Interactions with Matter". En Nondestructive Assay of Nuclear Materials for Safeguards and Security, 307–23. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-58277-6_14.

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AbstractThis chapter describes the interactions that neutrons have with matter. There is a description of microscopic interactions, such as fission, scattering and absorption, using the concept of cross-section. The idea of individual neutron interactions is extended to the macroscopic behavior of neutrons, giving rise to the calculation of reaction rates and mean free paths. The important quantities of moderation and neutron multiplication are introduced. There is a brief discussion of neutron shielding and transport calculational techniques.
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Kobayashi, Tooru, Shusuke Fujihara y Keiji Kanda. "Effective Thermal Neutron Collimation for Neutron Capture Therapy Using Neutron Absorption and Scattering Reactions". En Progress in Neutron Capture Therapy for Cancer, 95–99. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3384-9_19.

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de Groot, F. y J. Vogel. "Fundamentals of X-ray Absorption and Dichroism: The Multiplet Approach". En Neutron and X-ray Spectroscopy, 3–66. Dordrecht: Springer Netherlands, 2006. http://dx.doi.org/10.1007/1-4020-3337-0_1.

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Piotrowski, Tomasz, Piotr Prochoń y Magdalena Wojtkowska. "Neutron Radiation Shielding of C-PC and Geopolymers". En Springer Proceedings in Materials, 611–20. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-72955-3_63.

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AbstractThe aim of the paper is to evaluate neutron shielding efficiency of ordinary concrete, heavy-weight concrete and geopolymer concrete modified with epoxy additive. Evaluation was based on neutron shielding efficiency calculations. Since the commonly used fast neutron effective removal cross-section calculation does not take into account thermal neutron absorption reactions, a method adopted from the fast neutron effective removal cross-section calculation based on the macroscopic cross-section calculation for compositions is therefore applied. The results confirmed that an efficient neutron shield requires a balanced mixture of light and heavy nuclei and polymer modification is a proper way for increasing neutron shielding efficiency.
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Chun, Wang-Jae, Satoru Takakusagi, Yohei Uemura, Kyoko Bando y Kiyotaka Asakura. "X-Ray Absorption Fine Structure Analysis of Catalytic Nanomaterials". En X-ray and Neutron Techniques for Nanomaterials Characterization, 609–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-48606-1_11.

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Bovenkamp-Langlois, Lisa y Martha W. Schaefer. "The Characterization of Atomically Precise Nanoclusters Using X-Ray Absorption Spectroscopy". En X-ray and Neutron Techniques for Nanomaterials Characterization, 247–313. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-48606-1_5.

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Sasaki, Kotaro y Nebojsa Marinkovic. "X-Ray Absorption Spectroscopic Characterization of Nanomaterial Catalysts in Electrochemistry and Fuel Cells". En X-ray and Neutron Techniques for Nanomaterials Characterization, 315–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-48606-1_6.

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Volz, H. M., Sven C. Vogel, J. A. Roberts, A. C. Lawson, D. J. Williams y L. L. Daemen. "Effect of Strong Neutron Absorption on Texture and Diffraction Data Analysis". En Materials Science Forum, 119–24. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-975-x.119.

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Nakanishi, Tomoko M. "Water-Specific Imaging". En Novel Plant Imaging and Analysis, 3–37. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-4992-6_1.

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AbstractOur first target was water, namely, how to obtain a water-specific image nondestructively. Using a neutron beam, we could visualize water-specific images of plants, including roots and flowers, which were never shown before. Each image suggested the plant-specific activity related to water.We briefly present how to acquire the image and what kind of water image is taken by neutron beam irradiation. We present a variety of plant samples, such as flowers, seeds, and wood disks. It was noted that neutrons could visualize the roots imbedded in soil without uprooting. When a spatial image of the root imbedded in soil was created from many projection images, the water profile around the root was analyzed. Then, fundamental questions were raised, such as whether plants are absorbing water solution or water vapor from the soil, because there was always a space adjacent to the root surface and hardly any water solution was visualized there. The roots are in constant motion during growth, known as circumnutation, and it is natural that the root tip is always pushing the soil aside to produce space for the root to grow. If the roots are absorbing water vapor, then the next question is about metals. Are the roots absorbing metal vapor? Since we tended to employ water culture to study the physiological activity of plants, the physiological study of the plants growing in soil was somewhat neglected. Later, when we could develop a system to visualize the movement of element absorption in a plant, there was a clear difference in element absorption between water culture and soil culture.
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Milosavljević, Aleksandar R., Alexandre Giuliani y Christophe Nicolas. "Gas-Phase Near-Edge X-Ray Absorption Fine Structure (NEXAFS) Spectroscopy of Nanoparticles, Biopolymers, and Ionic Species". En X-ray and Neutron Techniques for Nanomaterials Characterization, 451–505. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-48606-1_8.

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Actas de conferencias sobre el tema "Neutron absorption"

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Tremsin, Anton S., Jason B. McPhate, John V. Vallerga, Oswald H. W. Siegmund, Winfried Kockelmann, Erik M. Schooneveld, Nigel J. Rhodes y W. Bruce Feller. "High resolution neutron resonance absorption imaging at a pulsed neutron beamline". En 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference (2011 NSS/MIC). IEEE, 2011. http://dx.doi.org/10.1109/nssmic.2011.6154356.

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Suleimanov, V., V. Hambaryan, A. Y. Potekhin, G. G. Pavlov, M. van Adelsberg, R. Neuhäuser, K. Werner, Ersin Göğüş, Ünal Ertan y Tomaso Belloni. "Absorption Features in Spectra of Magnetized Neutron Stars". En ASTROPHYSICS OF NEUTRON STARS 2010: A Conference in Honor of M. Ali Alpar. AIP, 2011. http://dx.doi.org/10.1063/1.3629497.

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Abdullah, Yusof, Anis Syukriah Ibrahim, Abdul Razak Daud y Mohd Reusmaazran Yusof. "Neutron absorption of Al-Si-Mg-B4C composite". En ADVANCING NUCLEAR SCIENCE AND ENGINEERING FOR SUSTAINABLE NUCLEAR ENERGY INFRASTRUCTURE: Proceeding of the International Nuclear Science, Technology and Engineering Conference 2015 (iNuSTEC2015). AIP Publishing LLC, 2016. http://dx.doi.org/10.1063/1.4940108.

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Sano, Tadafumi, Daisuke Ito, Jun-ichi Hori, Yoshiyuki Takahashi, Jaehong Lee, Naoya Abe y Ken Nakajima. "Imaging of Actinide Nuclides using Neutron Resonance Absorption". En 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). IEEE, 2018. http://dx.doi.org/10.1109/nssmic.2018.8824607.

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Grimmer, H., P. Böni, O. Elsenhans, H. P. Friedli, K. Leifer, P. Buffat y I. S. Anderson. "GROWTH AND STRUCTURAL CHARACTERIZATION OF Ni/Ti SUPERMIRRORS FOR NEUTRONS". En Physics of X-Ray Multilayer Structures. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/pxrayms.1994.tuc.8.

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The problems of producing and characterizing x-ray mirrors and supermirrors for neutrons are similar. In both cases an abrupt change of the optical properties at the interfaces, low interface roughness and stability of the structure (low diffusion) are required. Unlike for x-rays there are many elements with low neutron absorption. In order to get a large neutron optical contrast at the interfaces, two materials with large coherent scattering length densities of opposite signs have to be combined.
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Xie, Jinsen y Tao Yu. "Analysis of Isotopic Contributions to Doppler Coefficients of Inert Matrix Fuels". En 2014 22nd International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icone22-30620.

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The Minor Actinides (MA) generated by nowadays PWRs fleet has significant impact on environment and biosphere. Inert Matrix Fuels (IMF) is a possible way to reduce the production and hazard of MA in recent. From neutronic aspect, using the MCNP code with temperature related continuous neutron data, the present paper analyses the isotopic contributions to the Doppler Coefficients of certain types IMF fuels. It is concluded that, the Doppler Coefficients of Al2O3+ZrO2+MgO and ZrO2 based IMF fuels are much smaller than those containing ThO2, since the low neutron absorptions and lacking of resonance broadening of Al, Zr, Mg and O elements. For the same Inert Matrix, Reactor Grade Plutonium (RG-Pu) IMF fuels have more negative Doppler Coefficients than Weapon Grade Plutonium (WG-Pu) IMF fuels, which induce by the more abundance of resonance isotopes 240Pu, 242Pu in RG-Pu. Since the different neutron absorption cross-section profiles, the Er2O3 burnable poison has negative contribution to the Doppler Coefficient, however 10B, a typical 1/v absorber, is on the contrary way.
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Valencia, E., A. Algora, J. L. Tain, S. Rice, J. Agramunt, A. A. Zakari-Issoufou, A. Porta et al. "Total absorption γ-ray spectroscopy of beta delayed neutron emitters". En LA RABIDA 2012 INTERNATIONAL SCIENTIFIC MEETING ON NUCLEAR PHYSICS: Basic Concepts in Nuclear Physics: Theory, Experiments, and Applications. AIP, 2013. http://dx.doi.org/10.1063/1.4810827.

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Vartsky, David y Mark B. Goldberg. "Body composition studies: neutron activation analysis vs nuclear resonance absorption". En Fifth International Conference on Applications of Nuclear Techniques: Neutrons in Research and Industry, editado por George Vourvopoulos. SPIE, 1997. http://dx.doi.org/10.1117/12.267938.

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Binsted, Norman, Craig Owens y Mark T. Weller. "Local Structure in Solid Solutions Revealed by Combined XAFS/Neutron PD Refinement, using the Multiple-Scattering RMC Method". En X-RAY ABSORPTION FINE STRUCTURE - XAFS13: 13th International Conference. AIP, 2007. http://dx.doi.org/10.1063/1.2644431.

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Morgan, Bryan W., Matthew Van Zile, Piyush Sabharwall, Milos Burger y Igor Jovanovic. "Radiation-induced Negative Nonlinear Absorption in Glass and Sapphire". En CLEO: Applications and Technology. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleo_at.2022.jtu3a.34.

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We report the observation of negative nonlinear absorption in gamma and neutron-irradiated quartz glass, BK7 glass, and sapphire. Thermal annealing is effective in restoring the pre-irradiation optical properties.
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Informes sobre el tema "Neutron absorption"

1

Holden, N. E. Neutron scattering and absorption properties. Office of Scientific and Technical Information (OSTI), diciembre de 1993. http://dx.doi.org/10.2172/10106551.

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Macklin, R. L. y C. W. Alexander. Neutron absorption cross section of uranium-236. Office of Scientific and Technical Information (OSTI), noviembre de 1988. http://dx.doi.org/10.2172/6699291.

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Cooke, D. W., E. H. Farnum y B. L. Bennett. Optical absorption of neutron-irradiated silica fibers. Office of Scientific and Technical Information (OSTI), octubre de 1996. http://dx.doi.org/10.2172/414888.

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Smith, A. B. Remark on: the neutron spherical optical-model absorption. Office of Scientific and Technical Information (OSTI), junio de 2007. http://dx.doi.org/10.2172/929246.

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Cooke, D. W., E. H. Farnum y F. W. Clinard. Optical absorption and luminescence in neutron-irradiated, silica-based fibers. Office of Scientific and Technical Information (OSTI), abril de 1995. http://dx.doi.org/10.2172/114949.

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Mao, S. Photon and neutron responses of optical absorption dosimeters used at SLAC. Office of Scientific and Technical Information (OSTI), enero de 2000. http://dx.doi.org/10.2172/753283.

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Cutler, Theresa, Travis Grove, Kelsey Amundson, Jesson Hutchinson, Noah Kleedtke y Nicholas Wynne. The CWS Experiments -An Experimental Study of the Effects of Chlorine on Thermal Neutron Absorption. Office of Scientific and Technical Information (OSTI), septiembre de 2022. http://dx.doi.org/10.2172/1885731.

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Eberle, b. Relic Neutrino Absorption Spectroscopy. Office of Scientific and Technical Information (OSTI), enero de 2004. http://dx.doi.org/10.2172/826638.

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Huber, John Tal, Joshuah Miron, Brent Theurer, Israel Bruckental y Spencer Swingle. Influence of Ruminal Starch Degradability on Performance of High Producing Dairy Cows. United States Department of Agriculture, enero de 1994. http://dx.doi.org/10.32747/1994.7568748.bard.

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This research project entitled "Influence of Ruminal Starch Degradability on Performance of High Producing Dairy Cows" had the following objectives: a) Determine effects of feeding varying amounts of ruminally degradable starch (RDS) on efficiency of milk and milk protein production; and 2) Investigate digestive and metabolic mechanisms relating to lactation responses to diets varying in ruminal and total starch degradability. Four lactation studies with high producing cows were conducted in which steam-flaked (~ 75% RDS) was compared with dry-rolled sorghum (~ 50% RDS) grain. All studies demonstrated increased efficiency of conversion of feed to milk (FCM/DMI) and milk protein as amount of RDS in the diet increased by feeding steam-flaked sorghum. As RDS in diets increased, either by increased steam-flaked sorghum, grinding of sorghum, or increasing the proportion of wheat to sorghum, so also did ruminal and total tract digestibilities of starch and neutral-detergent soluble (NDS) carbohydrate. Despite other research by these two groups of workers showing increased non-ammonia N (NAN) flowing from the rumen to the duodenum with higher RDS, only one of the present studies showed such an effect. Post-absorptive studies showed that higher dietary RDS resulted in greater urea recycling, more propionate absorption, a tendency for greater output of glucose by the liver, and increased uptake of alpha-amino nitrogen by the mammary gland. These studies have shown that processing sorghum grain through steam-flaking increases RDS and results in greater yields and efficiency of production of milk and milk protein in high producing dairy cows.
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Bourdeau, J. E. y R. D. Dyer. Regional-scale lake-sediment sampling and analytical protocols with examples from the Geological Survey of Canada. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/331911.

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Regional-scale lake sediment surveys have been successfully used since the 1970s as a means for reconnaissance geochemical exploration. Lake sediment sampling is typically performed in areas with a lack of streams and an overabundance of small-sized (=5 km across) lakes. Lake sediments are known to have major, minor and trace element concentrations that reflect the local geology. Overall, lake sediment surveys are planned and conducted following four distinct stages: 1) background research, 2) orientation survey, 3) regional survey, and 4) detailed survey. At the Geological Survey of Canada, samples are usually collected from a helicopter with floats. Sample density ranges from 1 sample per 6 - 13 km2. Samples are collected from the centre of the lake using a gravity torpedo sampler which corresponds to a hollow-pipe, butterfly bottom-valved sampler attached by a rope to the helicopter. Collected sediment samples are then placed in labelled bags and left to air dry. Detailed field notes and additional samples (field duplicates), for the purpose of an adequate quality assurance and quality control program, are also taken. Samples are then milled and sent to analytical laboratories for element determination. Commonly used analytical methods include: X-ray fluorescence (XRF), atomic absorption spectroscopy (AAS), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and -mass spectrometry (ICP-MS), instrumental neutron activation analysis (INAA), and/or determination of volatile compounds and organic carbon using Loss on Ignition (LOI). Analytical data is first evaluated for quality (contamination, accuracy and precision). Numerous options for the analysis of lake sediment data exist, ranging from simple basic element concentration maps and statistical graphical displays together with summary statistics, to employing multivariate methodologies, and, more recently, using machine learning algorithms. By adopting the set of guidelines and examples presented in this manual, scientific researchers, exploration geologists, geochemists and citizen scientists will be able to directly compare lake sediment datasets from anywhere in Canada.
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