The Canadian Penning trap Mass Spectrometer (CPTMS) was reassembled and commissioned at Argonne National Laboratory. It consists of three systems: a laser desorption ion source, used for stable isotope production; a radio-frequency quadrupole ion trap (Paul trap); and a Penning trap, which sits inside a homogeneous 6 Tesla magnetic field. The CPTMS was tested using gold ions: these were accelerated toward the Paul trap, where they were accumulated and cooled down. They were then sent to the Penning trap, in which ions undergo circular motion. These motions were resonantly excited using an RF dipole electric field, and the resonant frequency was measured as a minimum in time-of-flight of the ejected ions as they were led to a region of low magnetic field, converting their cyclotron energy to axial kinetic energy. The apparatus was found to be operational: multiple-bunch accumulation was observed for the first time in a Paul trap, and the Fourier limited frequency resolution of 2 x 10--6 was attained for a one second excitation time in the Penning trap.

No description available.

The extensive equipment which is described has been built up for the study of magnetic moments of nuclei, particularly for accurate comparison of their gyromagnetic ratios, and the relative spins of isotopes. The nuclear induction and the nuclear absorption resonances of the proton have been observed. The induction resonance of B^11 has been observed at around 10 mc. in an alkaline solution of KB02. Its frequency has been compared with that of the proton in the same field giving a measure of the ratio of the two gyromagnetic ratios: ɤB/ɤP = 0.320904 ± 4.3 x 10^-6 [...]

This work covers spectroscopic studies of nuclei from different regions of the Segré chart whose properties illustrate the delicate balance between the forces in the atomic nucleus. Studies of nuclei far from stability offer new insights into the complex nucleon many-body problem. In nuclei with equal neutron and proton numbers (N = Z), the unique nature of the atomic nucleus as an object composed of two distinct types of fermions can be expressed as enhanced correlations arising between neutrons and protons occupying orbitals with the same quantum numbers. The bound N = Z nuclei with mass number A &gt; 90 can only be produced in the laboratory at very low cross sections. The related problems of identifying and distinguishing such reaction products and their associated gamma rays have prevented a firm interpretation of their structure even for the lowest excited states until recently. In the present work the experimental difficulties of observation of excited states in the N = Z = 46 nucleus 92Pd have been overcome through the use of a highly efficient, state-of-the-art detector system; the EXOGAM-Neutron Wall-DIAMANT setup, and a prolonged experimental running period. The level spacings in the ground state band of 92Pd give the first experimental evidence for a new spin-aligned neutron-proton (np) paired phase, an unexpected effect of enhanced np correlations for N = Z nuclei in the immediate vicinity of the doubly magic nucleus 100Sn. Excited states in 94Ru and 95Rh nuclei close to the double magic shell  Z = N = 50 have been studied in order to untangle the ambiguity of the spin and the parity of the lowest-lying states. The observed yrast structures are compared to results of large-scale shell model (LSSM) calculations and the strengths of hindered E1 transitions are used as a sensitive test of the LSSM parameters. The effect of single-particle-hole excitations is discussed in terms of the strength of hindered E1 transitions. Excited states of the odd-odd nucleus 162Ta have been observed using the JUROGAM/RITU experimental set-up. This nucleus is located in a transitional region in the nuclide chart which is between near-spherical nuclei and well-deformed nuclei, offering the possibility to study the emergence of collective phenomena and nuclear deformation (in particular the degree of triaxiality). The results, which are interpreted in the framework of the cranked shell model with total Routhian surface calculations, suggest an almost axially symmetric nuclear shape. The energy staggering between the signature partners of the yrast rotational bands has been deduced for eight odd-odd isotopes in the neighborhood of 162Ta nucleus and the special observed feature of signature inversion for these nuclei is discussed. / <p>QC 20140217</p>

In this thesis, the classical field model developed by Krasnitz et al. is used to compute quark and photon production in heavy ion collisions. The first part of the thesis serves as an independent verification of previous results for quark production. To do so, an iterative method is developed to solve the non-linear system of equations that gives the initial condition for the gluonic field. In the second part, the expression giving the photon production rate is simplified using the symmetries and properties of the Color Glass Condensate and McLerran-Venugopalan models. From the two Feynman diagrams that give the leading order contribution, one is much larger than the other. The dominant diagram is given by a continuum spectrum with a very prominent peak superimposed on it. / Dans cette thèse, le modèle développé par Krasnitz et al. basé sur les champs classiques est utilisé pour calculer la production de quarks et de photons dans les collisions d'ions lourds. La première partie de la thèse consiste en une vérification indépendante de certains résultats sur la production de quarks. Pour se faire, une méthode itérative est développée afin de solutionner le système d'équations non-linéaires qui donnent les conditions initiales du champ de gluon. Dans la seconde partie, l'expression donnant le taux de production de photons est simplifié en utilisant les symétries et les propriétés du Color Glass Condensate et du modèle de McLerran-Venugopalan. Deux diagrammes de Feynman donnent la contribution à l'ordre dominant mais l'un d'eux est plus important que l'autre. Le diagramme dominant donne un spectre continu superposé d'un pic proéminant.

Comparative features of the Cascade Model and the BUU model are presented and followed by a Quantum Theory Derivation of the Vlasov equation. Several modifications are made to the BUU model: the inclusion of a momentum-dependent potential instead of the usual Skyrme potential, the replacement of the "old" detailed balance cross section for delta reabsorption by the Danielewicz cross section, and a proper generation of the $ Delta$ mass, using a Monte-Carlo simulation. The effects of these ingredients on pion yields at beam kinetic energies in the range (0.4 AGeV-1.8 AGeV), and pion energy spectra at 90$ sp circ$ are analyzed. It is found that our numerical simulations agree quite well with experiments, except for pion energy spectra at low pion kinetic energies.

A high electric field RFQ device was developed and tested to investigate the design requirements needed for such a device to effectively cool and confine ions in gaseous environments. Segmented cylindrical quadrants placed 1mm apart were used to create axially confining fields similar to present trapping systems. High Q air-cored resonating coils were designed to drive the RFQ device at 4.76 MHz and place up to 5.4 kV between adjacent electrodes in vacuum. By removing the transformer cores from the resonating circuit and using a 1 kW RF amplifier it was found that up to 15 kV of RF potential could be achieved across adjacent quadrants at helium pressures of up to 80 Pa. / The main limiting factor associated to the device's function was found to be the power losses in the transformer coupling the resonant circuit to the RF amplifier. These results show that with a proper RF power supply RFQ confinement of ions severaI hundred times stronger than in present devices is indeed possible.

Pressure tubes made of Zr-2.5%Nb alloy are used to contain fuels and coolant in CANDU nuclear power reactors. The pressure tube oxidizes during reactor operation and hydrogen ingress through the oxide grown on the tube limits its lifetime. Little attention was paid to the intermediate tube manufacturing processes in enhancing the oxidation resistance. In addition, the oxide grown on the tube experiences various thermal cycles depending on the reactor shutdown and startup cycles. To address these two aspects and to better understand the oxidation process of the Zr-2.5Nb tube, research was conducted in two parts: i) effects of tube fabrication on oxidation behavior, and ii) thermal cycling behaviors of oxides grown on a pressure tube. / In the first part, the optimum manufacturing process was pursued to improve the corrosion resistance of Zr-2.5Nb tubes. Experimental micro-tubes were fabricated with various manufacturing routes in the stages of billet preparation, hot extrusion and cold drawing. These were oxidized in air at 400oC and 500oC, and in an autoclave at 360oC lithiated water. Microstructure and texture of the tubes and oxides were characterized with X-ray diffraction, scanning electron microscope and optical microscope. Special emphasis was given to examinations of the metal/oxide interface structures. A correlation between the manufacturing process and oxidation resistance was investigated in terms of tube microstructure and the metal/oxide interface structure. As a result, it was consistently observed that uniform interface structures were formed on the tubes which had a fine distribution of secondary phases. These microstructures were found to be beneficial in enhancing the oxidation resistance as opposed to the tubes that had coarse and continuous beta-Zr phases. Based on these observations, a schematic model of the oxidation process was proposed with respect to the oxidation resistance under oxidizing temperatures of 360oC, 400oC and 500oC. / In the second part, the oxides grown on a standard Zr-2.5Nb pressure tube were analyzed by X-ray diffraction peak broadening and line shift. Crystallite size, t-ZrO2 fraction and residual stress of the zirconium oxides were investigated upon several thermal cycles at delta T range of 500oC - 750oC. The oxide residual stresses measured by the sin2 psi method were always compressive around 2 GPa. Different stress-states were noticed with the oxides grown on different sections of pressure tube. The compressive stress was released when the oxide was thermally cycled at the highest delta T of 750oC. Discussion was given to the effects of anisotropic nature of thermal expansion coefficients and crystallographic texture on the stress-state of Zr oxides. / L'alliage Zr-2.5%Nb est présentement utilisé pour fabriquer les tubes contenant les grappes à combustion dans les réacteurs nucléaires CANDU. L'oxydation de ces tubes durant l'usage normale dans le réacteur et la pénétration d'hydrogène à travers leurs couches d'oxyde protectrice détériore leur durée de vie. Jusqu'à présent personne n'a porté attention à l'effet des paramètres de fabrication intermédiaire à augmenter la résistance de ces tubes à l'oxydation. De plus, l'oxyde sur le tube est soumis au cyclage thermique durant la mise en marche et l'arrêt du réacteur nucléaire. Pour mieux comprendre l'effet des deux aspects mentionnés ci-dessus et l'oxydation des tubes de Zr-2.5Nb, la présente recherche fut entreprise en deux parties: i) l'étude des variables de fabrication sur l'oxydation, et ii) l'étude du cyclage thermique sur l'oxyde des tubes. / Dans la première partie les paramètres de fabrication optimale sont cernés pour améliorer la résistance à la corrosion des tubes de Zr-2.5Nb. Des micro-tubes expérimentales furent fabriquées en variant les paramètres de fabrication aux étapes de préparation de la billet, de l'extrusion à chaud et de l'étirage à froid. Subséquemment, ceux-ci furent oxydés dans l'aire à 400oC et 500oC et dans un autoclave contenant de l'eau à 360oC en présence d'ions de lithium. La microstructure et la texture des tubes et de leurs oxydes ont été caractérisées par la diffraction rayons-x, la microscopie à balayage électronique et par microscopie optique. Une attention particulière a été portée à la structure de l'interface métal/oxyde. La corrélation entre les variables de procédé et la résistance à la corrosion des tubes a été étudiée en fonction de la microstructure du tube et la structure de l'interface métal/oxyde. Une interface uniforme fut constamment observée sur des tubes ayant une phase secondaire finement distribuée. Par la présente recherche, cette microstructure améliore la résistance à l'oxydation versus une microstructure de beta-Zr grossière et continue. Basée sur les observation de cette recherche, une modèle schématique du processus d'oxydation a été proposée par rapport à la résistance d'oxydation aux températures de 360oC, 400oC et 500oC. / Dans la seconde partie, les oxydes d'un tube de Zr-2.5Nb standard ont été analysés en mesurant l'élargissement et le déplacement des pics de diffractométrie de rayons-x. La taille des cristaux, la fraction de t-ZrO2 et la contrainte résiduelle des oxydes de zirconium furent caractérisés en fonction de plusieurs cycles thermique ayant un delta T entre 500oC et 750oC. La contrainte résiduelle, mesuré par la technique sin2 psi, fut toujours d'ordre compressive et autour de 2 GPa. Différents états de contrainte ont été observés sur les oxydes à différentes sections des tubes. Après le cyclage thermique ayant le plus grand delta T de 750oC, l'état de stress compressif est relâché. Une discussion est présentée pour relier les effets de l'anisotropie des coefficients d'expansion thermique et la texture cristallographique sur l'état de stress dans les oxydes de Zr.

Truths are illusions about which one has forgotten that this is what they are. - Nietzsche / On March 5th 1970, a long process of international negotiation and power brokering culminated into the Nuclear Proliferation Treaty. As a result the 121 signatory states were legally subject to the norms, values, principles, and behavioural prescriptions of the nuclear proliferation regime. Twenty-nine years after the treaty's entrenchment, however, the nuclear proliferation regime and its enforcement agencies still face many of the same challenges that have plagued its implementation since its conception. The purpose of this analysis is to examine the causal relationship between the perception of the political legitimacy among the signatory members of the NPT, the likelihood of adherence to these behavioural prescriptions and to provide a framework to understand what would make for a legitimate treaty in the eyes of its members. This analysis will reveal that signatory members of the NPT who perceive the treaty as illegitimate are more likely to either defect or disobey the obligations of the treaty than those signatory members who perceive the NPT to be legitimate. (Abstract shortened by UMI.)

Lambda production in central Au+Au collisions at 11.5 A&middot;GeV/c has been studied at forward rapidities (y > 2.2) using the upgraded E877 experimental setup at the AGS. Lambdas are measured via the charged decay channel: &Lambda; &rarr; ppi- and identified from the ppi - invariant mass spectra with the aids of a set of pair cuts. A comprehensive Monte Carlo simulation is made to extensively study the lambda reconstruction. The details of the data analysis for lambda identification are presented. The consistence of data analysis is examined by detailed comparison of the constructed proton and pion spectra with the previous results from the E877 1993 data set. The double differential multiplicities for lambda as a function of collision centrality are presented. Lambda rapidity distribution dN/dy is also studied. A pure thermal model is used to characterize the lambda spectra. The experimental results are compared to the predictions of the RQMD model (v2.3) in its cascade version and in the mode that takes into account the effect of mean-field. We also present the first measurement of the lambda directed flow at the AGS. In spite of limited statistics, a strong positive directed flow for lambda, which is comparable to the amplitude of the proton flow, is observed at forward rapidities (2.8 < y < 3.4) in the semi-central Au+Au collisions. The measured flow amplitude as a function of pt, v 1(pt), is in agreement with the predictions of the RQMD model.