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Dissertations / Theses on the topic 'Nuclear spectra'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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1

Blundell, S. "The theory of nuclear effects in atomic spectra." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355731.

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2

Hime, Andrew. "Heavy neutrino emission in nuclear beta decay spectra." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293432.

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3

Croft, David. "Automated assignment of high resolution nuclear magnetic resonance spectra." [S.l. : s.n.], 2000. http://www.diss.fu-berlin.de/2000/22/index.html.

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4

Bauer, Peter Helmuth. "Symmetries and fluctuations, an application to nuclear and atomic spectra." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1994. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/MQ31412.pdf.

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5

McBride, Vanessa A. "Cluster model investigation of nuclear spectra and electric quadrupole transitions." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/6537.

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Includes bibliographical references.
We review a cluster model for even-even nuclei and derive a new relation between the excitation energies and the electric quadrupole transition strengths of these nuclei. A novel method for determining the likely clustercore decompositions of a given nucleus is described, and is tested by comparing theoretical cluster model spectra with their experimental counterparts for a representative set of Yb isotopes. A further method, based on least squares fits to spectra, is also examined.
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6

Xu, Zhenxiang. "Analysis of the Unbound Spectra of 12Li and 13Li." Licentiate thesis, KTH, Kärnfysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-30287.

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The properties of unbound nuclei 12Li and 13Li are calculated within themultistep shell model in the complex energy plane by assuming that the spectraare determined by the motion of neutrons outside the 9Li core. It is foundthat in 12Li the ground state consists of an antibound 1/2+ state and thatonly this and a 1/2− and a 5/2+ excited states are physically meaningfulresonances. Calculations suggest that there is no bound or antibound statein 13Li.
QC 20110222
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7

Friedrich, J. O. "Frequency and spatial selectivity in nuclear magnetic resonance spectroscopy." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234964.

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8

Régnier, David. "Contribution à l'étude des gammas prompts de fission." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENI065.

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Cette thèse a essentiellement été motivée par la montée en puissance de la thématique des échauffements nucléaires en réacteurs. Elle avait pour objectif la mise en place de méthodes permettant la simulation de l'émission des gammas prompts de fission. Pour répondre à cette attente, différents algorithmes de désexcitation d'un noyau ont été implémentés. Ils ont été testés avec succès via plusieurs calculs d'application (rapport d'embranchement isomérique, largeur radiative totale, etc). Ces méthodes ont ensuite été mises en oeuvre dans le cadre du code de fission FIFRELIN. L'outil qui en résulte, permet la détermination d'un grand nombre d'observables de fission, dans le cadre d'un modèle unique. Une étude de sensibilité des résultats à différents éléments du calcul a été réalisée. Enfin, des simulations de la fission spontanée du 252Cf, et des fissions induites par neutrons thermiques sur l' 235U et le 239Pu ont été menées. Les spectres des gammas prompts pour ces trois systèmes fissionnants ont pu être déterminés. Les résultats obtenus sont en très bon accord avec les données expérimentales disponibles, dont certaines ont été publiées récemment (2012 et 2013)
This PhD thesis has essentially been motivated by the nuclear heating problematic in reactors. The main goal of this work was the production of methods capable of simulating the prompt gamma emission from fission. First of all, several algorithms for the treatment of the nucleus deexcitation were implemented. They have been succesfully tested through various calculations (isomeric branching ratio, total radiative width, etc). These methods were then incorporated in the frame of the fission code FIFRELIN. The tool which results from this work, enables the determination of numerous fission observables in the frame of a single consistent model. A sensitivity study of the results to several numerical and nuclear models has been realized. At last, calculation have been lead for the 252Cf spontaneous fission and the thermal neutron induced fission of 235U and 239Pu. The prompt gamma spectra obtained for those three fissionning systems have been determined. The results are in good agreement with available experimental data, including recent measurements published in 2012 and 2013
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9

Anastasiadis, Anastasios. "Calculation of γ-ray source spectra for used LWR nuclear fuels." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-377868.

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The present project aims to provide the γ-ray source spectrum (the gamma energies and their intensities) for a nuclear fuel, given its physical dimensions, its enrichment and the detailed knowledge of the burnup history. In a nuclear reactor, the nuclide concentrations within the nuclear fuel change due to nuclear transmutation caused by neutron irradiation and due to the radioactive decay during and after the irradiation. This alteration in the fuel composition is simulated in this project with a burnup-mode simulation using the reactor physics code Serpent 2. A second Serpent 2 photon-mode simulation follows as to evaluate the γ-radiation spectrum from the respective nuclides produced in the first simulation. Finally, the γ-ray mass attenuation coefficients for selected energies are evaluated by combining the fuel elemental concentrations with the corresponding mass attenuation coefficients for fresh fuel based on NIST XCOM database. To facilitate the repeated evaluation of the γ-ray source spectrum, a custom-made MATLAB® function, GetEmissions, that initiates the Serpent 2 simulations was created. This function utilizes the user input data, which are the fuel dimensions, the fuel enrichment and the burnup history, as to automatically create an input for the Serpent 2 code. Afterwards, it executes burnup and photon simulations, and finally extracts the data sought for, which are the emitted by the fuel γ-ray energies and their intensities (γ-ray source spectrum). In addition, for the given fuel characteristics, the function provides the mass attenuation coefficient for a selected γ-ray passing the fuel. Using the GetEmissions function, the gamma spectra from ten nuclear burnup history cases representing a scan through low and high burnup and short, medium and long cooling times are calculated. The resulting top ten gamma energies are listed by absolute intensity, and information about the mother nuclide and the decay is provided.
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10

Madian, Ashraf G. "Using affinity purification -- mass spectrometry to identify aryl hydrocarbon receptor nuclear translocator interacting proteins." Scholarly Commons, 2005. https://scholarlycommons.pacific.edu/uop_etds/605.

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The aryl hydrocarbon nuclear translocator (ARNT) belongs to the family of basic helix loop helix proteins. ARNT forms a heterodimer with aryl hydrocarbon receptor (AhR). This heterodimer binds to the dioxin responsive element (DRE) causing the regulation of the gene expression of some enzymes such as CYP1Al. Studies show that the ARNT-AhR heterodimer needs protein factors to bind to DRE, and most of these protein factors are still unknown. ARNT also heterodimerizes with hypoxia inducible factor 1 a (HIF-1 a) which mediates the cellular responses to hypoxia. The purpose of this research is to use a combination of affinity chromatography and mass spectrometry techniques to identify the proteins that interact with ARNT. We chose mouse liver as the protein source. We planned to isolate the ARNT interacting proteins from the mouse liver protein extract by using the TALON® resin column bounded with 6x HIS-ARNT. Two negative control experiments were done. The first one by the application of the liver extract only on non-ARNT bound column. The second one by the application of 100 mg of bovine serum albumin on 6x HIS-ARNT bound column. The mouse liver extract was applied on 6x HIS-ARNT bound column. The column was washed with an increasing concentration of potassium chloride (0.05 M- 1 M). ARNT was eluted with a buffer containing 250 and 500 mM imidazole. The different washing fractions were compared with the negative control experiments. There was no difference between this and experiment and negative controls. We also tested using in-vitro chemical cross-linking with formaldehyde. Some distorted bands that may '· represent crosslinked proteins appeared above ARNT molecular weight by the addition of 1% paraformaldehyde for 20 minutes at 37°C, and for 2 hours at 30° and room temperatures. These bands were absent in the negative control experiments. The mass spectrometric protocols for identification of trace amount of proteins using peptide mass fingerprinting were tested using a standard protein (Bovine Serum Albumin).
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11

Howard, Mark J. "Evaluation of the sonically induced narrowing of nuclear magnetic resonance spectra of solids." Thesis, Aston University, 1994. http://publications.aston.ac.uk/9601/.

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The Nuclear Magnetic Resonance (NMR) spectra of liquids contain a wealth of quantitative information that may be derived, for instance, from chemical shifts and spin-spin couplings. The available information depends on the incoherent rapid molecular motion that causes complicating effects present in the solid state to average to zero. Whereas liquid state NMR spectra show narrow lines, the corresponding NMR spectra from the solid state are normally composed of exceedingly broad resonance lines due to highly restricted molecular motion. It is, therefore, difficult to obtain directly as detailed information from the spectra of solids as from those derived from the liquid state. Studies on a new technique (SINNMR, the sonically induced narrowing of the NMR spectra of solids) to remove line broadening effects in the NMR spectra of the solid state are reported within this thesis. SINNMR involves narrowing the NMR absorptions from solid particles by irradiating them with ultrasound when they are suspended in a support liquid. It is proposed that ultrasound induces incoherent motion of the suspended particles, producing motional characteristics of the particles similar to those of rather large molecules. The first report of apparently successful experiments involving SINNMR[1] emphasised both the irreproducibility of the technique and the uncertainty regarding its true origin. If SINNMR can be made reproducible and the effect definitively attributed to the sonically induced incoherent motional averaging of particles, the technique could offer a simple alternative to the now classical magic-angle spinning (MAS) NMR[2] and the recently reported dynamic angle spinning (DAS)[3] and double rotation (DOR)[4] techniques. Evidence is presented in this thesis to support the proposal that ultrasound may be used to narrow the NMR spectral resonances from solids by inducing incoherent motion of particles suspended in support liquids and, additionally, for some solids, by inducing rotational motion of molecular constituents in the lattices of solids. Successful SINNMR line narrowing using 20 kHz ultrasound is reported for a variety of samples: including trisodium orthophosphate, polytetrafluoroethylene and aluminium alloys. Investigations of SINNMR line narrowing in trisodium phosphate have revealed the relationship between ultrasonic power, particle size and support liquid density for the production of optimum SINNMR conditions. It is also proposed that the incoherent motion of particles induced by 20 kHz ultrasound can originate from interactions between acoustically induced cavitation microjets and particles.
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12

Adams, Krysten Scott. "Using computational methods to predict NMR spectra for polyether compounds /." Electronic version (PDF), 2005. http://dl.uncw.edu/etd/2005/adamsk/krystenadams.pdf.

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13

Thompson, Jeffrey M. "The electronic structure and spectra of small metal clusters /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9648.

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14

Wang, Tao-Chin Lin. "Part I: Dispersion versus absorption (DISPA) line shape analysis. Part II: Ion trajectories and excitation techniques in fourier transform ion cyclotron mass spectrometry /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260135355759.

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15

Knight, Cheryl Lynn. "Application of IR and NMR spectroscopy to certain complexes of 8-hydroxyquinoline and 8-aminoquinoline." Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/22001.

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The IR spectra of twenty-one transition metal complexes of 8-hydroxyquinoline over the range 700 - 50 cm⁻¹ are discussed in relation to their known or inferred structures. The complexes are of three types: (a) the bis(aquo) complexes of the first row transition metal(II) ions, [M(ox)₂(H₂O)₂] (M =Mn, Fe, Co, Ni, Cu, Zn); (b) the corresponding anhydrous complexes, [M(ox)₂]n (M=Mn, Co, Ni, Cu, Zn) and (c) the complexes of the metal(III) ions, [M(ox)₃] (M = Sc, V, Cr, Mn, Fe, Co, Ga, Rh and In). Deuterated 8-hydroxyquinoline was. synthesized by the Skraup synthesis and has been used to assist in the assignment of the metal-ligand modes. The assignment of these bands was further based on ⁶⁴,⁶⁸Zn labellihg of the bis(aquo) zinc chelate and on the effects of metal ion substitution in relation to structural considerations based on crystal field theory. An investigation of the IR spectra of a series of -tris, bis and mono(8-aminoquinoline) complexes of the first transition row metal(II) perchlorates and halides is reported.
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16

Reese, Annabelle Wey. "Analysis of CW-EPR spectra and the internal dynamics of DNA /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/8569.

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17

Assatel, Omran. "Characterisation of photon and neutron spectra in medical linear accelerators using theoretical and experimental techniques." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/804743/.

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18

Marsh, James W. "High resolution measurements of neutron energy spectra from Am-Be and Am-B neutron sources." Thesis, Kingston University, 1990. http://eprints.kingston.ac.uk/20540/.

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A modelling methodology, consisting of tools and techniques, has been developed to achieve quality improvement in any area of a manufacturing organisation. A 3 step approach was piloted within the Test Department at ICL Kidsgrove which tests printed circuit boards manufactured at the factory. The first step was to produce a full process model and to use this to highlight non-conformances. The next step was to develop a cost of quality model. The information from this model is used to take cost prioritised and cost justified corrective actions. The final step is to prepare a procedure which defines to the customers how to use the cost of quality information effectively. This 3 step pilot methodology was then applied to indirect functions such as Finance and Maintenance through an implementation team. The process modelling step was also developed in other quality applications such as auditing and procedure preparation. The final methodology is currently being considered for adoption as a problem solving approach throughout ICL. The process modelling step is being incorporated into auditor training. The modelling methodology, developed through this research, provides a structured, disciplined approach to quality improvement.
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19

Petrie, Christian M. "Evaluation of Scattered Radiation in a Calibration Range Using Exposure Rate Energy Spectra." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313095840.

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20

Zhang, Zhan. "Neutron energy spectrum reconstruction method based for htr reactor calculations." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41195.

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In the deep burn research of Very High Temperature Reactor (VHTR), it is desired to make an accurate estimation of absorption cross sections and absorption rates in burnable poison (BP) pins. However, in traditional methods, multi-group cross sections are generated from single bundle calculations with specular reflection boundary condition, in which the energy spectral effect in the core environment is not taken into account. This approximation introduces errors to the absorption cross sections especially for BPs neighboring reflectors and control rods. In order to correct the BP absorption cross sections in whole core diffusion calculations, energy spectrum reconstruction (ESR) methods have been developed to reconstruct the fine group spectrum (and in-core continuous energy spectrum). Then, using the reconstructed spectrum as boundary condition, a BP pin cell local transport calculation serves an imbedded module within the whole core diffusion code to iteratively correct the BP absorption cross sections for improved results. The ESR methods were tested in a 2D prismatic High Temperature Reactor (HTR) problem. The reconstructed fine-group spectra have shown good agreement with the reference spectra. Comparing with the cross sections calculated by single block calculation with specular reflection boundary conditions, the BP absorption cross sections are effectively improved by ESR methods. A preliminary study was also performed to extend the ESR methods to a 2D Pebble Bed Reactor (PBR) problem. The results demonstrate that the ESR can reproduce the energy spectra on the fuel-outer reflector interface accurately.
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21

Stumpf, Christina [Verfasser], Robert [Akademischer Betreuer] Roth, and Gabriel [Akademischer Betreuer] Martinez-Pinedo. "Nuclear Spectra and Strength Distributions from Importance-Truncated Configuration-Interaction Methods / Christina Stumpf ; Robert Roth, Gabriel Martinez-Pinedo." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/1163013536/34.

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22

Kump, Paul. "Passive detection of radionuclides from weak and poorly resolved gamma-ray energy spectra." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3329.

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Large passive detectors used in screening for special nuclear materials at ports of entry are characterized by poor spectral resolution, making identification of radionuclides a difficult task. Most identification routines, which fit empirical shapes and use derivatives, are impractical in these situations. Here I develop new, physics-based methods to determine the presence of spectral signatures of one or more of a set of isotopes. Gamma-ray counts are modeled as Poisson processes, where the average part is taken to be the model and the difference between the observed gamma-ray counts and the average is considered random noise. In the linear part, the unknown coefficients represent the intensites of the isotopes. Therefore, it is of great interest not to estimate each coefficient, but rather determine if the coefficient is non-zero, corresponding to the presence of the isotope. This thesis provides new selection algorithms, and, since detector data is undoubtedly finite, this unique work emphasizes selection when data is fixed and finite.
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23

Gibson, David. "Investigating the kinetics and structural effects of azo dye photochemistry using NMR with in situ laser irradiation and ab initio (DFT) calculations." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/2439.

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Reversible cis-trans isomerisation of a series of commercially interesting yellow azo dyes has been studied using the technique of Nuclear Magnetic Resonance (NMR) spectroscopy with in situ laser irradiation. Photostationary state (PSS) spectra of the azo dyes, provided by coupling laser irradiation into the sample within the probe of the NMR spectrometer, have allowed observation of azo cis isomer species that would otherwise elude detection and characterisation by NMR due to their rapid thermal decay times. The NMR results have been combined with geometry optimised structures obtained through ab initio (DFT) calculations in order to allow visualisation of the trans and cis isomer species, and explain NMR spectral features. In the majority of cases, these in vacuo calculated structures show a great deal of correlation with NMR observations of asymmetric, cis-trans isomerisation-induced chemical shift changes for protons adjacent to the azo bond. The cis isomer spectral pattern for substituted naphthyl group protons can hence be used as a diagnostic tool in determining the correct cis isomer conformation in molecules where more than one conformation may exist. In addition to the aforementioned characterisation studies, in situ irradiation has provided the opportunity to undertake a thorough investigation of the kinetics of photoand thermal isomerisation for the same yellow dye series. The results of these studies have been combined with previous work on similar systems to provide an extensive data set, and conduct analysis in a systematic fashion. Adding fibre-reactive groups, varying phenyl and chlorotriazine ring substituents, and altering naphthyl group sulfonation patterns have a profound effect on both the photochemical and thermal rates of isomerisation in these systems. In certain cases, the same structural calculations noted earlier have proved useful in rationalising the identified kinetic differences. The presence of phenyl substituents ortho to the azo bond has been shown to increase the rate of thermal cis isomer decay. Additionally, substituents bonded to a fibrereactive group distant from the azo bond have an appreciable effect on the barrier to thermal cis-trans isomerisation, but little effect on the photochemical characteristics of each isomer. Several sulfonated naphthyl group patterns have been studied, leading to an observation that sulfonate groups positioned ortho to the azo bond assist in retarding thermal isomerisation, with sulfonate groups in other positions having a much smaller effect. One particular molecule, a component of a currently available commercial dye, was studied for its interesting and previously unexplained behaviour, both photochemical and chemical. The dye demonstrated photoisomerisation at low concentrations only, with aggregation preventing formation of the cis isomer at higher concentrations. The trans isomer was found to undergo degradation to a product which did not photoisomerise. This product was identified as a benzotriazinium compound by multinuclear 2D correlation NMR spectroscopy, formed by a reversible cyclisation reaction involving the azo bond.
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24

Campbell, Susan Christina. "Pharmaceutical polymorphism : an investigation using solid-state nuclear magnetic resonance spectroscopy." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/5021/.

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The study of two pharmaceutically active systems that each display polymorphism has provided a platform upon which to develop and apply solid-state NMR techniques in order to increase the understanding of the solid-state structure of small organic molecules. The multidisciplinary approach adopted has highlighted the advantages of solid-state NMR as a non-invasive probe of molecular conformation and crystallographic packing.Carbon-13 CP/MAS spectra of the two polymorphs of BRL55834 - a fluorinated benzopyran derivative - immediately suggest the presence of one and three molecules in the asymmetric unit. A lack of crystals suitable for single-crystal XRD has catalysed the application of high-power powder X-ray diffraction studies. Subsequent attempts at structure solution using Genetic Algorithm techniques are showing preliminary results that reinforce predictions made from solid-state NMR. Novel triple-channel techniques have aided assignment and resolution of die complex (^13)C CP/MAS spectra. Enrichment of the (^15)N site appears to have resulted in the formation of a new polymorph. Techniques for the analysis of detection Units have been developed using solid-state Raman spectroscopy and chemometric analysis. The aminoxanthine derivative, BRL61063, provides interesting inter-form variations in molecular disorder, solid-state packing, and hydrogen bonding. A previously basic understanding of the single-crystal XRD data has been further evaluated through the course of this Ph.D. and solid-state NMR spectral editing techniques have been developed and applied to identify these phenomena. Recrystallisation studies have produced two samples that appear to exist in an intermediate state between the rigid and mobile structural limits. Temperature variation causes interesting changes in the relaxation characteristics and natural abundance (^15)N and (^13)C CP/MAS spectra. Residual dipolar coupling effects vary in their manifestation within the (^13)C CP/MAS spectra of the polymorphic systems studied and comparison with the literature yields important information regarding molecular conformation. Nitrogen-15 enrichment and operation at higher magnetic field have been applied to reduce these second order effects. Finally, some distance has been travelled along the path towards decoupling (^14)N. Future development of this technique holds potential for resolution enhancement in the solid state spectra of most naturally occurring, nitrogen-containing molecules.
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25

Davis, John Christopher. "Understanding the origin of 35/37Cl and 16/18O isotope effects on 195Pt and 103Rh NMR nuclear shielding in selected Pt(IV) and Rh(III) complexes : a DFT study." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/95484.

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26

Bläckberg, Lisa. "Determination of representative spectra for the characterization of waste from a 450 GeV proton accelerator (SPS, CERN)." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-19037.

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Radioactive waste has been accumulated at CERN as unavoidable consequence of the use of particle accelerators. The elimination of this waste towards the final repositories in France and Switzerland requires the determination of the radionuclide inventory. In order to calculate the residual induced radioactivity in the waste, it is necessary to determine the spectra of secondary particles which are responsible for the material activation. In complex irradiation environments like in an accelerator tunnel it is expected that the secondary particle spectra vary with the characteristics of the machine components in a given section of tunnel. In order to obtain the production rates of the radionuclides of interest the spectra of secondary particles are to be folded with the appropriate cross sections. Though technically feasible, it would be impractical to calculate the particle spectra in every area of any machine and for all possible beam loss mechanisms. Moreover, a fraction of the waste has unknown radiological history, which makes it impossible to associate an item of waste to a precise area of the machine. Therefore it is useful to try to calculate “representative spectra”, which shall apply to a relatively large part of the accelerator complex at CERN. This thesis is dedicated to the calculation of representative spectra in the arcs of the 450 GeV proton synchrotron, SPS, at CERN. The calculations have been performed using the Monte Carlo code FLUKA. Extensive simulations have been done to assess the dependence of proton, neutron and pion spectra on beam energy, size of the nearby machine component and position with respect to the beam-loss point. The results obtained suggest that it is possible to define one single set of representative spectra for all the arcs of the SPS accelerator, with a minor error associated with the use of these. 

 

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27

MURA, LUIZ E. C. "Caracterização dos campos neutrônicos obtidos por meio de armadilhas de nêutrons no interior do núcleo do reator nuclear IPEN/MB-01." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9999.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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28

Hao, Jie. "A study on the application of independent component analysis to in vivo ¹H magnetic resonance spectra of childhood brain tumours for data processing." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/1064/.

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Independent component analysis (ICA) has the potential of automatically determining metabolite, macromolecular and lipid (MMLip) components that make up magnetic resonance (MR) spectra. However, the realiability with which this is accomplished and the optimal ICA approach for investigating in vivo MR spectra, have not yet been determined. A wavelet shrinkage de-noising based enhancement algorithm, utilising a newly derived relationship between the real and imaginary parts of the MR spectrum, is proposed. This algorithm is more robust compared with conventional de-noising methods. The two approaches for applying ICA, blind source separation (BSS) and feature extraction (FE), are thoroughly examined. A feature dimension selection method, which has not been adequately addressed, is proposed to set a theoretical guideline for ICA dimension reduction. Since the advantages and limitations of BSS-ICA and FE-ICA are different, combining them may compensate their disadvantages and lead to better results. A novel ICA approach involving a hybrid of the two techniques for automated decomposition of MRS dataset is proposed. It has been demonstrated that hybrid ICA provides more realistic individual metabolite and MMLip components than BSS-ICA or FE-ICA. It can aid metabolite identification and assignment, and has the potential for extracting biologically useful features and discovering biomarkers.
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29

Craig, Edward Clayton. "Application of dispersion versus absorption (DISPA) in Fourier transform nuclear magnetic resonance and Fourier transform ion cyclotron mass spectrometry /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487324944214076.

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30

Shehu, Yusufu. "Search for the electroweak production of supersymmetric particles in three-lepton events at the ATLAS detector with focus on compressed mass spectra." Thesis, University of Sussex, 2017. http://sro.sussex.ac.uk/id/eprint/67205/.

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This thesis presents a search for the electroweak production of supersymmetry using the dataset taken by the ATLAS detector at the Large Hadron Collider with √8 = 8 TeV during 2012. Events with three leptons are selected and required to satisfy additional kinematic criteria that define optimised signal regions. In these signal regions, Standard Model processes are discriminated against, whilst retaining a large fraction of events produced by specified compressed supersymmetry scenarios. Compressed refers to near massdegeneracy between the decaying gauginos and the final state gauginos. The expected number of Standard Model events are estimated using a combination of Monte Carlo and data-driven methods, where the predictions are tested against data in specifically designed validation regions. Exclusion limits are then set at 95% confidence level (CL) on via ℓ`L- and via WZ-decay scenarios for the decaying charginos and neutralinos. With the ℓ`L halfway between the decaying charginos and neutralinos and the final state neutralinos, there is a new sensitivity up to 250 GeV. In scenarios with large mass splitting, the decaying chargino and neutralino masses are excluded up to 740 GeV. Looking forward to the 13 TeV data-taking, a search for the electroweak production of supersymmetry with threelepton final states is presented, with a first look at an optimisation strategy to improve sensitivity to charginos and neutralinos.
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31

Habot, Simon, and University of Lethbridge Faculty of Arts and Science. "Time-symmetric shaped pulses for spin-1 excitation." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 1998, 1998. http://hdl.handle.net/10133/71.

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Shaped pulses can be used for uniform spin-1 excitation. The effects of the pulses on spin-1 excitation is seen as distortion of two types: phase distortions and amplitude distortions. By reducing the distortions a spin-1 excitation becomes more uniform. In the case of time-symmetric shaped pulses, spin-1 excitation is free of phase distortions. The spin-1 excitation in that case can be made uniform over a larger frequency bandwidth. The number of possible shaped pulses is so large that a computer-aided search is needed to find the desirable shaped pulses. A theoretical analysis is used to find the connection between a shaped pulse and the corresponding spin-1 excitation. The theoretical analysis in density matrix formalism gives the spin-1 excitation in closed-form expressions that are too complicated. In such a case the connection between a shpaed pulse and spin-1 excitation is not straightforward. A brute-force search for a desirable shaped pulse can consume too much computer time and thus time the scope of the search. By using the formalism of quaternions in the theoretical analysis, spin-1 excitation is presented in simple closed form expressions. It is then shown tht if the choice is limited to time-symmetric shaped pulses then these closed form expressions become much simpler. It is also shown that a spin-1 excitation is free of phase distortions in that case. These simple closed form expressions can be used as the building blocks of a much more concise program code for the computer aided search. As a result a computer aided search for a desirable shaped pulse becomes much faster in speed and larger in scope. More shaped pulses for improved spin-1 can be found.
xiii, 99 leaves : ill. ; 28 cm.
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32

Camou-Arriola, Fernando Alberto Josue. "Structure determinations of natural products and related molecules." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184773.

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Structures were determined for 48 new natural products and several related compounds by NMR methods. One new natural product and two unnatural product structures were determined by X-ray diffraction. Molecular mechanics calculations on two indoles related to the neurotransmitter serotonin and on some synthetic cyclophanes were used to gain information about their preferred conformations. Considerable time is wasted redetermining the structures of known natural products when they are encountered in new sources. To help alleviate this problem, a database which searches on proton NMR chemical shifts was developed.
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33

Tse, Man-kit, and 謝汶桀. "Structural characterization and domain dissection of human XAF1 protein, and application of solvent-exposed-amide spectroscopy inmapping protein-protein interface." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43223801.

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34

Travia, Anderson Dingfelder Michael. "Interaction cross sections needed for simulation of secondary electron emission spectra from thin metal foils after fast proton impact." [Greenville, N.C.] : East Carolina University, 2009. http://hdl.handle.net/10342/1906.

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Thesis (M.S.)--East Carolina University, 2009.
Presented to the faculty of the Department of Physics. Advisor: Michael Dingfelder. Title from PDF t.p. (viewed Apr. 23, 2010). Includes bibliographical references.
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35

Paul, Jessica Nicole. "A rapid, reliable methodology for radionuclide characterization of wet or dry stored used nuclear fuel via the application of algorithm-enhanced scintillator survey spectra." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53833.

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The growing concern regarding regulation and accountability of plutonium and SNM produced in commercial and research nuclear reactor fuel has driven the need for new spent nuclear fuel characterization methods to enable quantification and qualification of radioisotopes contained in used fuel in a reliable, quick, and inexpensive manner, with little to no impact on normal reactor operating procedures. This research aims to meet these objectives by employing advanced computational radiation transport methods incorporated into an algorithm to post process scintillator detector data gathered from used nuclear fuel in a spent fuel pool or in air. An existing, novel post processing algorithm, SmartID, has been updated to extract and identify unique photopeaks represented in the underwater environment for pool cooled used fuel. The resulting spectral data will be post-processed using an updated SmartID algorithm folded with deterministic adjoint results to render both qualitative and quantitative fuel content and irradiation estimates. This work has much significance to the nuclear power industry, safeguards, and forensics communities, since it yields this information at room temperature for a relatively low cost.
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36

Heindrichs, Axel Stefan Dirk. "New methodologies in solid state NMR." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342111.

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37

Bai, Xin. "Correction of the magnetic field values of E781 SELEX spectrometer system, using a sign correction approach." Virtual Press, 2001. http://liblink.bsu.edu/uhtbin/catkey/1217400.

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In this thesis, the current vs. magnetic field relationships for four magnets, M1, M2, M3, and Hyperon of FNAL Experiment E781 (the charm baryon study) havel,een studied on the basis of algorithms involving sign corrections pertaining to remedying incorrect FNAL EPICURE readout system's current and magnetic field values for E78 I's 4 magnets.After analyzing previous BSU personnel's work involving re-averaging of the current and magnetic field output values for E78 1, further research was carried out in this thesis activity regarding the correction of the algebraic signs of certain current and magnetic field values in the FNAL EPICURE read out values inputted into E781' data bank.Firstly, a code was developed to merge the four files of current and magnetic fields for the four magnets of E78 1, all into one file. Then, an algorithm for a sign correction program was developed in order to both sort the merged data and correct the current and magnetic field signautomatically.In order to obtain a better understanding of the effect of the incorrect sign for a magnet's current and magnetic field on analysis results, a statistical result was summarized. Finally, some conclusions were obtained.
Department of Physics and Astronomy
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38

Engelbrecht, Leon de Villiers. "A study of isotope-effects in the high-resolution 195Pt NMR spectra of octahedral complexes of the type [PtCl6-n(OH)n]2-, n = 0-6, in water." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80186.

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Thesis (MSc)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The high-resolution 195Pt NMR signals (128.8 MHz) of most of the octahedral mixed-ligand Pt(IV) complexes in the series [PtCl6-n(OH)n]2-, n = 0-6, have been recorded in aqueous solutions at 293 K. These signals show characteristic 35/37Cl isotope-induced fine structure that results from the presence of several isotopologues in samples with a natural chlorine isotope distribution; each 37Cl isotope incorporated into the Pt coordination sphere of one of these complexes affords a fixed upfield (low frequency) isotope shift of between 0.17 and 0.22 ppm, depending on the particular complex. This assignment is confirmed by the excellent agreement between the natural abundances of the various isotopologues and the relative contributions of the corresponding signals to the overall area of the experimental spectrum of the particular isotoplogue set, obtained by a non-linear least-squares line fitting procedure. These results confirm that the 195Pt magnetic shielding in isotopomers differing only in the combination of the two chlorine isotopes coordinated in sites trans to hydroxido-ligands are indistinguishable under these experimental conditions, unlike those of similar isotopomers in the related series of aqua-complexes [PtCln(H2O)6-n]4-n, n = 3-5, as reported by Koch and co-workers. Moreover, the order of 195Pt shielding for the members of all stereoisomer pairs in the series of hydroxido-complexes is the reverse of that reported for the corresponding pairs in the aqua-series. These and other observations are interpreted qualitatively in terms of the relative strengths of the trans-influences of aqua-, hydroxido- and chlorido-ligands and the effect of these on bond displacements in these complexes. The 195Pt NMR spectra of especially the complexes cis-[PtCl2(OH)4]2- and [PtCl(OH)5]2- show remarkable fine structure in a ca. 45 % 18O-enriched aqueous solution; apart from additional signals resulting from 18O-containing isotopologues, the resonance signals of isotopomers differing in the combination of 16/18O isotopes in sites trans to chlorido-ligands are partially resolved. The effect of temperature on the 35/37Cl isotope-induced fine structure in the 195Pt signals of [PtCl6]2- and [PtCl(OH)5]2- was investigated in the range 283-308 K; some interesting differences are observed. 195Pt relaxation time measurements for [PtCl6]2- in this temperature range reveal that line-broadening is at least partially responsible for the loss of resolution between the signals of isotopologues of this complex as the temperature is increased, possibly due to the spin-rotation relaxation mechanism. The temperature coefficient of 195Pt shielding and the magnitude of isotope shifts in the spectra of the complexes in this series show interesting correlations with the 195Pt shielding itself; an interpretation of these observations is presented.
AFRIKAANSE OPSOMMING: Die hoëresolusie 195Pt NMR seine (128.8 MHz) van die oktaëdriese gemengde-ligand Pt(IV) komplekse in die reeks [PtCl6-n(OH)n]2- is waargeneem in waterige oplossing by ʼn temperatuur van 293 K. Hierdie seine toon ʼn karakteristieke 35/37Cl isotoop-geïnduseerde fynstruktuur as gevolg van die teenwoordigheid van verskeie isotopoloë in monsters met ʼn natuurlike chloor isotoopverspreiding. Die verplasing van ʼn 35Cl isotoop deur ʼn 37Cl isotoop in die Pt koördinasiesfeer van hierdie komplekse lei tot ʼn laefrekwensie isotoopverskuiwing van die 195Pt resonansiesein van tussen 0.17 en 0.22 ppm, afhangend van die spesifieke kompleks. Die toekenning van resonansieseine in hierdie spektra word ondersteun deur die goeie ooreenstemming tussen die berekende natuurlike verspreiding van isotopoloë en die persentasie area bydrae van die ooreenstemmende pieke tot die area van volledige stel seine van die chemiese spesie, soos bepaal deur ʼn nie-linieêre kleinste-kwadrate passingsmetode. Hierdie resultate bevestig dat vir isotopomere waarvan slegs die kombinasie van chloorisotope wat in posisies trans tot hidroksido-ligande gekoördineer is ʼn ononderskeibare 195Pt magnetiese skerming waargeneem word, m.a.w. ʼn enkele resonansiesein word vir hierdie isotopomere gemeet, anders as gerapporteer deur Koch en medewerkers vir die verwante aqua-komplekse [PtCln(H2O)6-n]4-n waar n = 3-5. Verder is die order van 195Pt magnetiese skerming vir stereoisomere in hierdie hidroksido-komplekse in elke stereoisomer paar die teenoorgestelde van dit waargeneem vir die ooreenstemmende aqua-komplekse. Hierdie waarnemings word kwalitatief geïnterpreteer in terme van die verskillende trans-invloede van die chlorido-, aqua- en hidroksido-ligande en die effekte daarvan op bindingslengtes in die komplekse. In ʼn ongeveer 45 % 18O-verrykte monster toon die 195Pt seine van veral die komplekse cis-[PtCl2(OH)4]2- en [PtCl(OH)5]2- uitsonderlike fynstruktuur vanweë die addisionele seine van 18O-bevattende isotopoloë en die parsiële resolusie van die seine van isotopomere wat verskil in die kombinasie van 16/18O isotope wat trans tot chlorido-ligande gekoördineer is. ʼn Studie is gemaak van die uitwerking van temperatuur op die 35/37Cl isotoop-geïnduseerde fynstruktuur in die 195Pt seine van die komplekse [PtCl6]2- en [PtCl(OH)5]2- in die gebied 283-308 K; interessante verskille is waargeneem. 195Pt magnetiese relaksasietyd metings vir die kompleks [PtCl6]2- in waterige oplossing in hierdie temperatuurgebied toon dat verbreeding van resonansieseine ten minste gedeeltelik verantwoordelik is vir die waargenome verlies aan resolusie tussen die seine van isotopoloë namate die temperatuur styg; die verbreeding van seine kan waarskynlik aan die spin-rotasie relaksasiemeganisme toegeskryf word. Die temperatuurkoëffisiënt van 195Pt magnetiese skerming en die grootheid van isotoopverskuiwings in die spektra van die hidroksido-komplekse in hierdie reeks toon interessante korrelasies tot die 195Pt magnetiese skerming; ʼn interpretasie van hierdie waarnemings word voorgestel.
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39

Ashbrook, Sharon Elizabeth. "New NMR techniques for the study of quadrupolar nuclei." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342238.

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40

ZAHN, GUILHERME S. "Estudo do decaimento beta do sup(193)Os." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11440.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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41

Frankland, L. "Interpretation of fp-shell nuclei, '5'3Mn and '5'3Fe." Thesis, University of Brighton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367331.

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42

Reed, Alan Thomas. "Decay studies of neutron-rich nuclei." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367175.

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43

CUNHA, TATIANA F. da. "Aplicação do poli(epsilon-caprolactona) com estrutura estrelada para obtenção de microesferas biorreabsorvíveis." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10544.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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44

Hawcroft, Deborah. "A search for superdeformed and hyperdeformed states in '2'2'2Th and '2'3'2U." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367227.

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45

GROPPO, DANIELA P. "Caracterização dosimétrica de amostras de BeO em feixes de radiação alfa, beta e X por técnicas luminescentes." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10576.

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IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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46

Shen, Chun. "The standard model for relativistic heavy-ion collisions and electromagnetic tomography." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405931790.

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47

Artiles, Oswaldo. "Multinucleon Short-range Correlation Model for Nuclear Spectral Functions." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3384.

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The main goal of the research presented in my dissertation was to develop a theoretical model for relativistic nuclear spectral functions at high missing momenta and removal energies based on the multi-nucleon short-range correlation (SRC) model. The nuclear spectral functions are necessary for the description of high energy nuclear processes currently being studied at different labs such as JLAB, LHC and FNAL. The model followed the effective Feynman diagrammatic approach in order to ac-count for the relativistic effects important in the SRC domain. In addition to the two-nucleon (2N) SRC with center of mass motion contribution, the contribution of the three-nucleon SRCs to the spectral functions was also derived. The latter was modeled based on the assumption that the 3N SRCs are a product of two sequential short range nucleon-nucleon (NN) interactions. The nuclear spectral functions models were derived from two theoretical frameworks for evaluating covariant Feynman diagrams: In the first, referred to as the virtual nucleon approximation, the Feynman diagrams were reduced to the time ordered non-covariant diagrams by evaluating the nucleon spectators in the SRC at their positive energy poles, neglecting explicitly the contribution from vacuum diagrams. In the second approach, referred to as the light-front approximation, the boost invariant nuclear spectral function was formulated in the light-front reference frame in which case the vacuum diagrams are kinematically suppressed and the bound nucleon is described by its light-front variables such as momentum fraction, transverse momentum and invariant mass. On the basis of the derived nuclear spectral functions, the corresponding computational models were developed from which the numerical estimates of the SRC spectral functions, the SRC momentum distributions, and the SRC density matrices were obtained.
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48

Engelson, Eric. "Excited nucleon and delta spectra from lattice QCD." College Park, Md.: University of Maryland, 2009. http://hdl.handle.net/1903/9564.

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Thesis (Ph.D.) -- University of Maryland, College Park, 2009.
Thesis research directed by: Dept. of Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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49

Sowazi, Khanyisa. "Investigating the Gamma-ray Strength Function in 74Ge using the Ratio Method." University of the Western Cape, 2018. http://hdl.handle.net/11394/6513.

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>Magister Scientiae - MSc
An increasing number of measurements reveal the presence of a low-energy enhancement in the gamma-ray strength function (GSF). The GSF, which is the ability of nuclei to absorb or emit rays, provides insight into the statistical properties of atomic nuclei. For this project the GSF was studied for 74Ge which was populated in the reaction 74Ge(p,p')74Ge* at a beam energy of 18 MeV. The data were collected with the STARS-LIBERACE array at Lawrence Berkeley National Laboratory. Silicon detector telescopes were used for particle identi cation and rays in coincidence were detected with 5 clover-type high-purity germanium detectors. Through the analysis particle- - coincidence events were constructed. These events, together with well-known energy levels, were used to identify primary rays from the quasicontinuum. Primary rays from a broad excitation energy region, which decay to six 2+ states could be identi ed. These states and the associated primary rays are used to measure the GSF for 74Ge with the Ratio Method [1], which entails taking ratios of e ciency-corrected primary -ray intensities from the quasicontinuum. Results from the analysis of the data and focus on the existence of the low-energy enhancement in 74Ge will be discussed. The results are further discussed in the context of other work done on 74Ge using the ( , ') [2], (3He,3He') [3] and ( , ') [4] reactions.
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50

Whitfield, Melinda D. "Doppler-Broadening of Light Nuclei Gamma-Ray Spectra." TopSCHOLAR®, 2010. http://digitalcommons.wku.edu/theses/1075.

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Non-destructive methods of material interrogation are used to locate hidden explosives and thwart terrorism attempts. In one such method materials are bombarded with neutrons which react with the nuclei of the atoms within causing a de-excitation process emitting a gamma-ray. The spectrum displayed by the collection of these gamma-rays gives valuable information regarding the material’s elemental make-up. It has been hypothesized that gamma-rays from neutron-induced gamma-ray reactions on light elements with atomic numbers less than 20, including most of the gamma-rays of interest in explosives detection, are Doppler-broadened. This thesis focuses on the gamma ray spectra from the 4438 keV gamma ray in the 12C (n, n’γ) reaction wherein Doppler broadening was investigated. A graphite sample was exposed to 14 MeV neutrons and the 12C gamma ray spectra collected using an HPGe detector positioned at four different angles with respect to the neutron beam; near 00, 450, 900 and 1350. No other experimental parameter was changed. The resultant gamma ray spectra indicated Doppler broadening had occurred.
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