This work investigates the feasibility to perform an experiment at CERN n_TOF to study the fission cross section and fission fragment angular distribution (FFAD) of the 230Th(n,f) reaction. An analysis of fission fragment energy losses in the experimental target resulted in a choice of target thickness of 0.1 µm (100 µg/cm2 ), which yields good transmission out of the target at up to 45° emission angles from the target normal. A detection setup using ten PPAC detectors with nine thorium targets interleaved in between them was investigated, where the detectors and targets were tilted 45° with respect to the neutron beam. This makes it possible to measure all emission angles needed with respect to the neutron beam in order to determine the FFAD. For the experimental area EAR2 at n_TOF, a prediction of the count rate in the experiment resulted in low statistical uncertainties after a few weeks of beam time, which indicates that an experiment like this is feasible. / Detta projekt undersöker genomförbarheten av ett experiment vid CERN n_TOF för att mäta tvärsnittet och fördelningen av emissionsvinklar av fissionsfragment (FFAD) från 230Th(n,f)-reaktionen. En analys av energiförlusterna av fissionsfragment inuti torium-provet resulterade i en optimal provtjocklek på 0.1 µm (100 µg/cm2 ), vilket medför att fissionsfragment som emitteras i vinklar upp till 45° från provets normal har hög sannolikhet att transmitteras ut ur provet. En detektionsuppställning med tio PPAC-detektorer med nio toriumprov mellan dem undersöktes, där detektorerna och proven antogs vara snedställda med 45° från neutronstrålens riktning. Detta möjliggör detektion av fissionsfragment i alla vinklar som är nödvändiga för att kunna mäta hela FFAD. För experimentanläggningen EAR2 vid n_TOF, resulterade en uppskattning av antalet detekterade fissionsevent per sekund i låga mätosäkerheter efter ett par veckor av mättid, vilket antyder att experimentet är görbart.

In zukünftigen kerntechnischen Anlagen können die Materialien Blei und Bismut eine größere Rolle spielen als heute. Für die Planung dieser Anlagen werden verlässliche Wirkungsquerschnittsdaten benötigt. Insbesondere der Neutronentransport in einem Blei-Spallationstarget eines beschleunigergetriebenen unterkritischen Reaktors hängt stark von den inelastischen Streuquerschnitten im Energiebereich von 0,5 MeV bis 6 MeV ab. In den vergangenen 20 Jahren wurden elastische und inelastische Neutronenstreuquerschnitte mit hoher Präzision für eine Vielzahl von Elementen am PTB-Flugzeitspektrometer gemessen. Zur Erzeugung der Neutronen wurde hauptsächlich die D(d,n)-Reaktion genutzt. Aufgrund des Q-Wertes der Reaktion und der verfügbaren Deuteronenenergien können Neutronen im Energiebereich von 6 MeV bis 16 MeV erzeugt werden. Die Messung von Wirkungsquerschnitten bei niedrigeren Energien erfordert somit die Verwendung einer anderen neutronenerzeugenden Reaktion. Hierfür wurde die 15N(p,n)15O-Reaktion ausgewählt, da sie die Erzeugung monoenergetischer Neutronen bis zu einer Energie von 5,7 MeV erlaubt. In dieser Arbeit wird die 15N(p,n)-Reaktion auf ihre Eignung als Quelle monoenergetischer Neutronen in Streuexperimenten untersucht. Die Untersuchung der Reaktion beinhaltet die Messung von differentiellen Wirkungsquerschnitten für ausgewählte Energien und die Auswahl von optimalen Targetbedingungen. Differentielle elastische und inelastische Neutronenstreuquerschnitte wurden unter Anwendung der Flugzeitmethode für Blei bei vier Energien zwischen 2 MeV und 4 MeV gemessen. Eine Bleiprobe mit natürlicher Isotopenzusammensetzung wurde verwendet. Für den Nachweis der gestreuten Neutronen wurden NE213 Flüssigszintillatoren verwendet, deren Nachweiswahrscheinlichkeit gut bekannt ist. Winkelintegrierte Wirkungsquerschnitte wurden mit einem Legendre-Polynomfit unter Verwendung der Methode der kleinsten Quadrate bestimmt. Zusätzlich erfolgten Messungen für die isotopenreinen Streuproben 209Bi und 181Ta bei 4 MeV Neutronenenergie. Die Ergebnisse werden mit denen früherer Experimente und aktuellen Evaluationen verglichen. / In future nuclear facilities, the materials lead and bismuth can play a more important role than in today’s nuclear reactors. Reliable cross section data are required for the design of those facilities. In particular the neutron transport in the lead spallation target of an Accelerator-Driven Subcritical Reactor strongly depends on the inelastic neutron scattering cross sections in the energy region from 0.5MeV to 6 MeV. In the recent 20 years, elastic and inelastic neutron scattering cross sections were measured with high precision for a variety of elements at the PTB time-of-flight spectrometer. The D(d,n) reaction was primarily used for the production of neutrons. Because of the Q value of the reaction and the available deuteron energies, neutrons in the energy range from 6MeV to 16MeV can be produced. For the cross section measurement at lower energies, however, another neutron producing reaction is required. The 15N(p,n)15O reaction was chosen, as it allows the production of monoenergetic neutrons with up to 5.7MeV energy. In this work, the 15N(p,n) reaction was studied with focus on the suitability as a source for monoenergetic neutrons in scattering experiments. This includes the measurement of differential cross sections for the neutron producing reaction and the choice of optimum target conditions. Differential elastic and inelastic neutron scattering cross sections were measured for lead at four energies in the region from 2MeV to 4MeV incident neutron energy using the time-offlight technique. A lead sample with natural isotopic composition was used. NE213 liquid scintillation detectors with well-known detection efficiencies were used for the detection of the scattered neutrons. Angle-integrated cross sections were determined by a Legendre polynomial expansion using least-squares methods. Additionally, measurements were carried out for isotopically pure 209Bi and 181Ta samples at 4MeV incident neutron energy. Results are compared with other measurements and recent evaluations.

The electromagnetic form factors in elastic electron-proton scattering are used to determine the finite size of the proton. Through the use of Feynman Diagrams and Fermi's "golden rule", several key results for cross sections of elastic electron scattering will be re-derived. This will ultimately lead to the calculation for the Rosenbluth formula, that describes in detail the process of electron-proton scattering. Furthermore, the process used for determining the size of the proton from the form factors will be shown. In addition, a recent paper by R. Jaffe, which argues the validity of this process, will be discussed in detail. / Physics

The Starkville Quadrangle is a hotspot for geological research. The Late Cretaceous is represented by the Demopolis Formation in the northeast corner of the quadrangle, followed by the Ripley Formation, and the Prairie Bluff Formation. The K-Pg boundary is exposed in the quadrangle, and the remarkable paleontology is of global importance. The Clayton Formation is the first Paleocene unit. Where the Clayton Formation channel sands are in contact with the underlying Prairie Bluff Formation, springs occur. Springs were a rare source of water in the Black Prairie and spurred the settlement of the area over 10,000 years ago. The Paleocene Porters Creek Formation occurs in the southwest corner of the Quadrangle. Quaternary streams left Holocene to Pleistocene alluvium and terraces overlying the subcrop. This project provides a modern geologic map and stratigraphic framework as a background for future research in the Starkville Quadrangle.

Our group has been studying chiral recognition in gas phase using mass spectrometry for more than 10 years. We are interested in gas phase studies of fundamental interactions because the gas phase avoids complications and masking effects that may arise upon solvation. Therefore, the results of gas phase experiments can be directly compared with those of high-level computational studies. In chapter 2, I studied the roles of hydrogen bonding and pi stacking in gas phase chiral recognition between aromatic crown molecules and aromatic amines. High affinity between host and guest doesn't necessarily result in better recognition. If the affinity is too high, both host enantiomers will bind to the chiral guest very tightly so little discrimination is observed. In order to build an efficient chiral recognition system, we need to select a host and guest that have intermediate binding affinity. Hydrogen bonding is another significant factor that controls the host-guest affinity. In the case of host 1, more hydrogen bonds results in better recognition. We also find that the degree of chiral recognition is greater in the gas phase than in solution. Modeling at the B3LYP/6-31G* level is qualitatively correct, but quantitative agreement with experiment is poor. Inspired by Rekharsky's work which shows successful induced chiral recognition with an achiral host (cucurbituril) in solution, we tested the possibility of applying cucurbiturils as gas phase chiral recognition containers in chapter 5. Conferring chirality on cucurbiturils makes the chiral recognition happen in a restricted space, which might strengthen or hinder the discrimination. By comparing our results with Rekharsky's, we showed the role of solvent in this chiral recognition process. In the gas phase, the enantiodiscrimination does not happen between the "leaving MP" and the "approaching" stronger chiral binder. Because hydrophobic effects are absent in the gas phase, it is possible that the hydrophobic methyl substituent of 2-methylpiperazine and the stronger chiral binder might not be simultaneously included inside the cavity. Therefore, we do not observe enantiodiscrimination in gas phase. The dissociation experiment for the CB[7] ternary complex shows that sec-butylamine binds externally to the CB[7] host. Further, the heterochiral diastereomer is more stable than the homochiral diastereomer. This conclusion is consistent with Rekharsky's result in solution. For more than 15 years, the most common ionization method in our lab has been electrospray ionization. However, ESI is subject to problems with ion suppression, especially when the sample is a mixture or it has a high concentration of salt. The easily ionized molecules tend to scavenge the available charges in the spray solution and dominate the resulting ion population even though other compounds may be present in high abundance. Nanoelectrospray usually yields cold ionization, and analyte suppression can be greatly reduced at nanospray flow rates. Therefore, we constructed a porous polymer monolith (PPM) nanospray emitter similar to that described by Oleschuk et al. and characterized the properties of the PPM emitter. This work is described in chapter 3. Our tests show that this PPM nanospray emitter possesses some special analytical properties: decreased ion suppression, quite stable spray, strong signal intensity and good reproducibility in emitter performance. Chapter 4 deals with the application of the new CRAFTI method to negative ions. CRAFTI stands for cross-sectional areas by Fourier transform ICR. The CRAFTI technique measures collision cross sections, providing a probe of the gas phase conformations of supramolecular complexes. Our preliminary work has shown that CRAFTI is applicable to positive ions, so we further demonstrate the application of the newly-developed method to negative ions in this work. Based on the fact that the experimental cross sections correlate linearly with the theoretical values, we have obtained evidence that CRAFTI is a valid method for negative ions. However, some problems remain. First, we are still working to understand the physical meaning of the CRAFTI cross sections. The absolute values we obtain are generally greater than those obtained from momentum transfer cross section calculations modeled in helium. Second, the precision of the measurements (currently about 2-3%) is still larger than we desire. We need to carefully tune the excitation and isolation amplitudes to make the signal strong and monoisotopic for weak ions. CRAFTI is a very promising and attractive method because FT-ICR provides accurate mass-to-charge measurement along with the cross section measurement. In other words, one technique is sufficient to obtain the shape, size and mass of a molecule simultaneously.

Nutrient pollution as a result of excessive fertilizer application is of major concern for Florida's water resources. Excess fertilizer can be lost either via surface runoff or by leaching through the soil mass eventually reaching water bodies and leading to eutrophication. The focus of this study is to analyze the effect of low rainfall intensities and overland flow from an adjacent roadway surface on the loss of nutrients from two different fertilizers. This study focuses on the fate of the nitrogen and phosphorus present in fertilizers utilized by the Florida Department of Transportation for the stabilization of highway embankments. This research was performed on a field-scale test bed and rainfall simulator located at the Stormwater Management Academy at the University of Central Florida. The loss of nutrients was measured from two soil and sod combinations typically found in Florida and used for highway stabilization -Pensacola Bahia on AASHTO A-2-4 soil and Argentine Bahia on AASHTO A-3 soil. Two different fertilizers were analyzed, an all-purpose, quick-release 10-10-10 (N-P-K) fertilizer previously used by FDOT, and the new slow-release 16-0-8 (N-P-K) fertilizer, both applied at a rate of 0.5 lb/1000 ft2 consistent with FDOT's practice. Each combination was analyzed under two rainfall intensities: 0.1 in/hr and 0.25 in/hr at a slope consistent with typical highway cross-sections found in Florida. Nutrient losses were measured by collection of runoff and/or baseflow that escaped the test bed. Additionally, from the soil samples collected throughout the testing period, the mass of the nutrients was compared to the mass balances values based on literature from a previous study on fertilizers performed at the Stormwater Management Academy. The experimental findings of this study showed that there was a reduction in total nitrogen and total phosphorus on both A-2-4 soil and A-3 soil at the 0.25 in/hr intensity as a result of switching to the slow-release 16-0-8 (N-P-K) fertilizer. Results from the 0.1 in/hr rainfall intensity, which were available only for the A-2-4 soil, showed that at this intensity there was no apparent benefit to the switch in fertilizers. Furthermore, it was found that less total nitrogen and total phosphorus was lost from A-3 soil than A-2-4 soil at 0.25 in/hr when using 10-10-10 (N-P-K). At 0.1 in/hr, there was no apparent difference in total nitrogen lost. However, less total phosphorus was lost at this intensity. The results of this study showed that there is an environmental benefit to applying slow-release fertilizers. This was more significant for the 0.25 in/hr intensity than the 0.1 in/hr intensity at which no apparent benefit was found. In addition, it was found that runoff was a greater source of nutrient loss than baseflow, although baseflow losses were substantial. Furthermore, it was found that total nitrogen tends to be lost via both pathways of runoff and baseflow while phosphorus has a lower tendency to leach through the soil but readily runs off the soil surface. It was also observed that because fresh sod tends to be heavily fertilized, applications of fertilizer could be reduced or avoided entirely after sod placement and applied as needed.

The objective of this research is to determine the three-dimensional stiffness matrix of a rectangular cross-section helical coil compression spring. The stiffnesses of the spring are derived using strain energy methods and Castigliano's second theorem. A theoretical model is developed and presented in order to describe the various steps undertaken to calculate the spring's stiffnesses. The resulting stiffnesses take into account the bending moments, the twisting moments, and the transverse shear forces. In addition, the spring's geometric form which includes the effects of pitch, curvature of wire and distortion due to normal and transverse forces are taken into consideration. Similar methods utilizing Castigliano's second theorem and strain energy expressions were also used to derive equations for a circular cross-section spring. Their results are compared to the existing solutions and used to validate the equations derived for the rectangular cross-section helical coil compression spring. A finite element model was generated using IDEAS (Integrated Design Engineering Analysis Software) and the stiffness matrix evaluated by applying a unit load along the spring's axis, then calculating the corresponding changes in deformation. The linear stiffness matrix is then obtained by solving the linear system of equations in changes of load and deformation. This stiffness matrix is a six by six matrix relating the load (three forces and three moments) to the deformations (three translations and three rotations). The natural frequencies and mode shapes of a mechanical system consisting of an Additional mass and the spring are also determined. Finally, a comparison of the stiffnesses derived using the analytical methods and those obtained from the finite element analysis was made and the results presented. / Master of Science

In this study, we analyse the $\Lambda$-$\Lambda$ hyperon channel in proton-proton scattering, $pp \mapsto \Lambda\Lambda + K^+K^+, \,\,\Lambda\mapsto p+\pi^-$, with a proton beam energy of $4.5$ GeV using the High Acceptance Di-Electron Spectrometer (HADES) at GSI.The purpose of the study presented here is to measure the production cross-section for the $\Lambda$-$\Lambda$ channel. %at the above beam Kinetic energy. The following measurement will be the first at this energy scale (CoM: $\sqrt{s}=3.46$ GeV).We develop a multi-stage analysis strategy to first determine the acceptance-reconstruction efficiency for the $\Lambda$-$\Lambda$ channel from simulations produced according to phase space.The analysis of data is perforned for three different event selections: inclusive ($ pp \mapsto \Lambda\Lambda + X$), semi-exclusive ($ pp \mapsto \Lambda\Lambda + K^+ +X$) and the fully exclusive.For each selection, the data is represented by a two-dimensional histogram, where the axes correspond to the $p+\pi^-$ invariant mass of the respective $\Lambda$ candidate. %The same strategy was employed on the experimental data to build a $\Lambda$-$\Lambda$ 2D correlation matrix. The \sloppy{$\Lambda$-$\Lambda$ signal} is determined using a Statistical sideband analysis (SSB) and a Linear least squares (LLS) fit.The inclusive selection provides the most significant $\Lambda$-$\Lambda$ signal.Cross-section values corresponding to the two analyses  are calculated as weighted average of the result of the three selections.The production cross-section for $\Lambda$-$\Lambda$ in $pp$ collisions at $\sqrt{s}=3.46$ GeV is measured \sloppy{to be $59\pm27$ nb} (one standard deviation uncertainity).

<p> An experimental study of turbulent flow of air around a 90º bend is reported in this thesis. Four 90º bends of aspect ratio 1, 3, 5 & 10 and radius ratio 1.0 have been tested in the Reynolds number range of 1 × 10⁵ to 5 × 10⁵. The loss in total pressure across the bend (or elbow) is reported for two discharge conditions (1) and the elbow discharging to a plenum chamber through a constant area duct of a length equal to 4 hydraulic diameters; (2) the elbow discharging to the plenum chamber directly. A comparison of the experimental results is made with the curves given in NACA report L4F26 which have been reproduced in the recently published SAE Aero-Space Manual. </p> <p> Various other flow parameters, such as velocity profiles, turbulence levels and pressure distributions are also given in this thesis. </p> / Thesis / Master of Engineering (ME)

A search for the Higgs boson produced with large transverse momentum and decaying as H -&gt; bb is presented, using the 80 fb^{-1} from the dataset collected by the ATLAS detector at sqrt{s}=13 TeV. The Higgs boson is reconstructed as a large-R jet with two b-tagged variable radius track-jets. The work focuses on a peculiar event topology in which the Higgs is produced in association with another Large-R jet. Considering events with reconstructed pT above 480 GeV and with a reconstructed mass from 70-230 GeV, a signal significance of 1.6 sigma for the Higgs and of 5 sigma for the V (Z boson + W boson) is observed. Furthermore, the new Full Run2 analysis is presented, using 136 fb^{-1} from the dataset collected by the ATLAS detector at sqrt{s}=13 TeV. The strategy up to the computation of the expected sensitivity for the Higgs boson is presented in this thesis. The validation of the background modeling is described in details, including tests on data. A preliminary extraction of the Z boson signal is performed and the measured signal strength corresponds to muZ = 0.82 +/- 0.09.