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X-ray intensity fluctuation spectroscopy of the ordering in Cu3AuZhang, Yongfang, 1976- January 2007 (has links)
No description available.
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Model for precise detection of bone edgesRamesh, Visvanathan 06 February 2013 (has links)
A mathematical model which is used to detect bone edges accurately is described in this thesis. This model is derived by assuming the X-ray source to be a square region. It is shown that for an ideal X-ray source (point source), the bone edge lies exactly at the location of maximum first derivative of the imaged object's transmission function. However, for the non-ideal case, it is shown that the bone edge does not lie at the maximum first derivative location. Also, it is shown that an offset can be calculated from the edge parameters. The Marr- Hildreth edge detector is used to detect the initial estimates for edge location. Precise estimates are obtained by using the facet model. The offset is then calculated and applied to these estimates. / Master of Science
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Development of Radon Detectors for Earthquake PredictionPartos, Alma, Schöldström, Astrid January 2023 (has links)
The purpose of this project is to simulate the detection of γ-ray spectra emitted by radon isotopes and their daughters. This is done as a contribution to the development of radiation detectors to be used in a research project investigating the possibility of using increased amounts of the radioactive gas radon as an earthquake precursor. Before the onset of an earthquake, microcracks are formed in the surrounding stone structures due to stress, releasing greater than usual amounts of radon gas contained within the rock pores. A way of predicting an upcoming earthquake would then be to place radiation detectors in areas with high seismicity in order to measure possible changes. This could be done in soil, groundwater (via springs, wells, and boreholes), or air. In this project, we aim to understand how measurements in groundwater would differ from ones in air, and how to best make use of the spectra as seen in water. This was done by simulating a scenario in which a scintillator detector, made of cesium iodide, is placed in each media and then assessing the resulting γ-ray spectra.
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Anomaly detection and classification of sparse gamma-ray spectra using machine learning algorithms for depleted uranium remediationFinney, Austin 01 May 2020 (has links)
The quality of the spectral data collected by radiological survey systems depends on many factors including the survey environment, configuration of the system and its detectors, and the radionuclides in question. Algorithms in the field of machine learning have the potential to classify data that would be difficult and time-intensive for a human to analyze. Depleted and natural uranium spectra are of particular interest due to known contamination at domestic sites and world-wide. Several machine learning classifiers were developed with data collected from laboratory experiments. This thesis demonstrates the potential of machine learning algorithms to discriminate gamma-ray emitting sources using sparse, or low-count statistic, data. Effectiveness has been demonstrated for discriminating chemical forms of uranium, mixtures with differing uranium isotope distributions, and predicting source masses given certain detector geometries and a known target distribution. All activity has been supported by the U.S. Army Engineering Research and Development Center (ERDC).
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The classification of human bone using x-ray fluorescenceGreen, Rebecca, T. January 1985 (has links)
Call number: LD2668 .T4 1985 G73 / Master of Science
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Transmission electron microscopy study on the formation of SiNX interlayer during InAlN growth on Si (111) substrateKuei, Chun-Fu January 2015 (has links)
Ternary indium aluminum nitride (InXAl1-XN) semiconductor is an attractive material with a wide-range bandgap energy varied from ultraviolet (Eg(AlN): 6.2 eV) to near infrared (Eg(InN): 0.7 eV). With tuning composition, it can be widely used to many optoelectronic device applications. In this thesis, I have studied InXAl1-XN film deposited on Si (111) substrate using natural and isotopically enriched nitrogen as reactive gas by reactive magnetron sputter epitaxy (MSE). Four series of experiments were performed, which are I. InAlN presputtering, II. InAlN sputter deposition, III. InAlN direct deposition, and IV. InAlN direct deposition using isotopically enriched nitrogen. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The θ-2θ XRD scan confirms that the designed composition x = 0.17 of InXAl1-XN film was obtained. TEM images shows that an amorphous interlayer with a thickness ranging from 1.2 nm to 1.5 nm was formed between Si substrate and InXAl1-XN film. However, high-resolution TEM shows that the interlayer actually contains partial crystalline structures. EDX line profile indicates that the chemical composition of the amorphous interlayer is silicon nitride (SiNX). By comparing d-spacing measurement of partial crystalline structures with EDX line profile, it reveals that partial SiNX crystal is formed in the interlayer. Nonetheless, the samples (IAD01, IAD02, IAD03, IAD04), grown without presputtering procedure, contain both crystalline SiNX and InXAl1-XN embedded in the amorphous interlayer. It means that SiNX and InXAl1-XN film can be directly grown on the substrate in the beginning of deposition. Moreover, the samples (IAD01, IAD03), quenched directly after deposition, have less crystalline structures in the interlayer then the samples (IAD02, IAD04), maintained at 800℃ for 20 min.
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Portable X-ray fluorescence and nuclear microscopy techniques applied to the characterisation of southern African rock art paintingsSteyn, Ruan 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Non-destructive portable X-ray Fluorescence (pXRF) and Particle Induced X-ray
Emission (PIXE) were used to measure the elemental concentration of rock art
fragment paintings. For pXRF the Amptek Silicon Drift Detector (SDD) and Niton
XL3t spectrometers were used to perform the measurements. These two
spectrometers use different spectrum analysis methods. The Peak Deconvolution
(PD) analysis method is used for the Amptek SDD and an Inverse Overlap Matrix
(IOM) method is used for the Niton XL3t spectrometer.
The pXRF methods were validated by using alloys, coins and rock standards. The
validation is important to establish if the pXRF technique is properly understood and
used and to advance the investigation to more complex rock art paintings, with
heterogeneous and layered properties. The elemental concentrations obtained for
the Standard Reference Materials (SRMs), which were used for the validation, were
in good agreement with that of the known concentration of the SRMs.
The two rock art fragments which were analysed from the Mount Ayliff and Ha
Khotso caves were part of larger rock art painting prior to it being naturally exfoliated
from the rock. For the Mount Ayliff rock art, seven paint points, two unpainted rock
(varnish) point adjacent to the paint and the back of the rock were analysed. The
colour of the paint ranged from black, shades of brown and shades of red. The black
paint is due to manganese or charcoal. The red colour is due to iron oxide and the
red-brown colour is due to Hematite (a type of ferrous oxide) [1]. For the Ha Khotso
fragment the paint on the front of the rock and the rock substrate (back of the rock)
were analysed.
For the Mount Ayliff rock art fragment the results for both pXRF spectrometers
indicated that the elemental concentration was uniform across the fragment. This is
due to the formation of a uniform layer of minerals such as silica and calcium
introduced by the seepage of water through the cracks of the cave. Therefore no
correlation could be established between the colour of the rock art paint and the
elements detected, as was found with the work done by Peisach, Pineda and
Jacobson [1]. For the Ha Khosto rock fragment a relation between the Ca
composition and the cream colour of the rock art paint was established. Both the
PIXE and pXRF techniques were used to identify the compound concentrations of
the Ha Khotso rock art fragment. The comparison between the two techniques
highlights the complexity of rock art paint analysis. The results from the PIXE
elemental mapping indicated the non-uniform distribution of the elements in the
analysed region. From the rock art fragment measuring the analysed points 5 times and obtaining the
same results, indicated that the particle size and inhomogeneities did not have much
effect on the compound compositions.
In order to obtain high accuracy results with pXRF, sound scientific methodology with
specific knowledge and expertise, not only about the XRF technique, but also about
the sample under investigation is required. For alloy analysis pXRF is well suited, the
analysis of geological material however more complex, since they are composed
predominately of low atomic elements e.g. silicon, aluminium, magnesium, sodium,
oxygen and carbon – all of which are excited with very low efficiencies. / AFRIKAANSE OPSOMMING: Nie-beskadigended X-straal Fluoresensie (pXRF) en Deeltjie Geinduseerde X-straal
emmissie (PIXE) was gebruik om die elementêre konsentrasie van die rotstekeninge
in hierdie studie te bepaal. Vir die pXRF-tegniek is die “Amptek Silicon Drift Detector
(SDD)” en die “Thermo Scientific Niton XL3t” spektrometers gebruik gemaak om die
metings uit te voer. Die twee spektrometers maak gebruik van verskillende spektrum
analiseringsmetodes.Die “Peak Deconvolution (PD)” analiseringsmetode is gebruik
vir die “Amptek SDD” en die “Inverse Overlap Matrix (IOM)” analiseringsmetode is
gebruik vir die “Thermo Scientific Niton XL3t” spektrometer.
Vir die validasie van die pXRF-metode is van allooie, muntstukke en rots
standaarded gebruik gemaak. Die validasie is belangrik om vas te stel of die pXRF
tegniek behoorlik verstaan en gebruik word en om die ondersoek te bevorder na
meer komplekse rotstekeninge, met heterogene en lae eienskappe. Die element
konsentrasies wat vir die “Standard Reference Material (SRM)” wat gebruik is vir die
validasie, was in 'n goeie ooreenkoms met die van die konsentrasie van die SRM,
wat bekend is.
Die twee rotstekeninge wat ontleed is van die Mount Ayliff en Ha Khotso grotte en
was deel van 'n groter rots kuns skildery voordat hul natuurlik afgebreek het. Vir die
Mount Ayliff rotskuns, is sewe verf punte, twee ongeverfde rots (vernis) punte
aangrensend aan die verf en die agterkant van die rots ontleed. Die kleur van die
verf het gewissel van swart, skakerings van bruin en skakerings van rooi. Die swart
verf kan toegeskryf word aan mangaan of houtskool. Die rooi kleur is as gevolg van
ysteroksied en die rooi-bruin kleur is as gevolg van Hematiet ('n tipe van yster
oksied) [1]. Vir die Ha Khotso rotskuns is die verf aan die voorkant van die rots en
die rots substraat (agterkant van die rots) ontleed.
Vir die Mount Ayliff rotstekening het die resultate vir beide pXRF spektrometers
aangedui dat die elementele konsentrasie uniform oor die rotstekening is. Dit is as
gevolg van die vorming van 'n uniforme lagie van silica en kalsium, wat deur die
sypeling van water deur die krake van die grot na die oppervlak van die rotstekening
beweeg het. Daarom kon geen korrelasie tussen die kleur van die rotstekening en
die elemente wat gemeet is bepaal word nie, soos gevind deur die werk van
Peisach, Pineda en Jacobson [1]. Vir die Ha Khotso rotstekening is ‘n verband
tussen die room kleur van die rotstekening verf en Ca konsentrasie gevind. Beide die
PIXE en pXRF tegnieke is gebruik om die konsentrasies van die Ha Khotso
rotstekening te identifiseer. Die vergelyking tussen die twee tegnieke beklemtoon die
kompleksiteit van rotstekening verf analise. Die resultate van die PIXE elementele
karakterisering het aangedui die nie-eenvormige verspreiding van die elemente in
die ontlede area. Deur die meting van die ontlede punte 5 keer te herhaal, en dieselfde resultate
verkry, is ‘n aanduiding dat die deeltjie grootte en inhomogeniteite nie veel invloed
op die elementele konsentrasies het nie.
Ten einde 'n hoë akkuraatheid resultate te kry met pXRF, moet goeie wetenskaplike
metode toegepas word met spesifieke kennis en kundigheid, nie net oor die XRF
tegniek, maar ook oor die rotstekening wat ondersoek word vereis. pXRF is wel
geskik vir die ontleding van allooie, die ontleding van geologiese materiaal is egter
meer kompleks, aangesien die materiaal hoofsaaklik bestaan uit lae atoomgetal
elemente bv silikon, aluminium, magnesium, natrium, suurstof en koolstof - wat almal
met lae doeltreffentheid opgewek en baie afgerem word in die materiaal.
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Nanoparticles prepared from reactive metal surfactantsWarne, Barnaby January 2000 (has links)
No description available.
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THE ELECTRONIC STRUCTURE OF ORGANOMETALLIC CARBONYL, NITROSYL, THIONITROSYL, AND CYANIDE COMPLEXES BY GAS PHASE X-RAY AND ULTRAVIOLET PHOTOELECTRON SPECTROSCOPY.HUBBARD, JOHN LEE. January 1982 (has links)
Transition metal-ligand interactions in several groups of closely related organometallic complexes are discussed from the results of both valence and core photoelectron experiments. Particular attention is given to the novel experimental aspects, including a charged particle oscillator He II source, sample introduction and containment, and data collection and spectral analysis procedures not normally associated with gas phase photo-electron spectroscopy. The application of the ionization experiments begins with a reassessment of the bonding in the group VIb metal hexacarbonyls. He I ionization data of unprecedented quality for the predominantly metal d t₂g level of Cr(CO)₆ and W(CO)₆ reveals for the first time the presence of metal-carbon vibrational fine structure. These positive ion M-C stretching frequencies are significantly reduced from neutral ground state values, giving direct evidence of the pi back-bonding nature of the t₂g level. The next chapter focuses on the comparison of the metal-nitrosyl interactions in the trans-X-W(CO)₄NO complexes to the isoelectronic/isostructural metal-carbonyl interactions in the X-Re(CO)₅ complexes (X = Cl,Br,I). A further comparison of carbonyl and nitrosyl bonding, as well as the first photoelectron assessment of metal-thionitrosyl bonding, is addressed in the next chapter by comparing the valence and core ionization data for CpCr(CO)₂NO and CpCr(CO)₂NS (Sp = η⁵-C₅H₅) to the data reported earlier for CpMn(CO)₃ and CpMn(CO)₂CS. The final chapter of the dissertation compares the electronic structure of the CpFe(CO)₂X complexes to their CpCr(NO)₂X analogs (X = Cl,Br,I,CH₃,CN). The essence of this work fully contrasts the Fe(CO)₂ and Cr(NO)₂ functional groups.
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Measurement of ion and electron populations in laser produced plasmas by x-ray absorption spectroscopyHoarty, David John January 1998 (has links)
No description available.
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