Two problems in nuclear physics are investigated using microscopic semi-classical models. The first model, developed to study heavy ion collisions, is based on the Boltzmann-Uehling-Uhlenbeck theory and has been extended to include one-body fluctuations. It has been successfully applied at low and intermediate energies and a comparison between simulations and an experiment done at the Michigan State University cyclotron facility has yielded very good agreement. The second is a nuclear structure model based on the Thomas-Fermi theory and describes nuclear rotations. It has been used to calculate nuclear shapes and limiting angular momenta across the periodic table. It has been found that it breaches the gap between classical Liquid Drop calculations and quantum Hartree-Fock calculations. Agreement with experimental results is satisfactory.

A new method for on-line laser spectroscopy of radioactive atoms based on the resonant ionization spectroscopy of laser desorbed radioactive samples has been devised. An experimental set-up has been installed on-line at the ISOCELE mass separator in Orsay (France) and experiments have been performed on the transitional nuclei region around Z = 79. Four new isotopes $ sp{194,196,198,199}$Au have been added to the series of the isotopic shift measurements in gold and results on the neutron deficient isotopes down to $ sp{186}$Au have been obtained, confirming the nuclear ground-state shape transition from oblate to prolate between $ sp{187}$Au and $ sp{186}$Au. The first isotopic shift measurements on radioactive platinum have been obtained on $ sp{186,188,189}$Pt. Indications of a shape transition have been observed between $ sp{186}$Pt and $ sp{188}$Pt. The extracted experimental changes in mean square charge radii $ delta$ $ sp{A,A{ sp prime}}$ along isotopic chains are compared to self-consistent Hartree-Fock plus BCS calculations.

The model of nuclear dynamics according to the Boltzmann-Uehling-Uhlenbeck (BUU) equation which incorporates fluctuations is presented. This model is employed to calculate heavy-ion reactions in the intermediate energy regime $(20 leq E sb{lab}/A leq 200MeV)$. Using a local (Skyrme-type) interaction, the model is capable of reproducing diverse features of spectator and participant observables. A finite range interaction is introduced to generate diffuse nuclear surfaces in the Vlasov approach. The peripheral reaction of $ sp{40}Ar$ on $ sp{27}Al$ is calculated with this interaction. Characteristic features of the angular distribution of the projectile-like fragments and its correlation with the target-like fragments are in agreement with experiments. / The stability condition of self-consistent Vlasov solutions with a finite range interaction is derived. This condition is cast into an eigenvalue equation. The lowest eigenmodes correspond closely to giant vibration modes. The relationship of these eigenmodes to the time-dependent Vlasov equation is explored.

We investigate modifications to the AdS-CFT correspondence such that it more closely resembles thermal QCD (Quantum Chromodynamics) by allowing it to have fundamental flavors, have couplings that run with energy scale and become a thermal theory. Using these modifications, we calculate three transport coefficients: the shear viscosity, the bulk viscosity and the thermal conductivity and their ratios with the entropy density (s) slightly away from the conformal boundary, to investigate the effects of changing the energy scale to first order in the small parameters of the theory. We compare these results to those obtained using the original conformal theory: shear/s=1/4*pi and bulk/s=thermal/s=0. We find that the shear viscosity does change to first order while the bulk viscosity does not. The thermal conductivity changes to first order, but this change is multiplied by a parameter that remains free in our calculations. This parameter can be fixed by introducing an energy scale cutoff to the theory. / On analyse des modifications à la correspondance AdS-CFT pour qu'elle se rapproche de la théorie QCD (Chromodynamique Quantique) thermique. Ces modifications sont : avoir des flaveurs fondamentales, avoir des couplages qui courent avec l'échelle d'énergie et devenir une théorie thermique. Ensuite, on calcule trois coefficients de transport : la viscosité de cisaillement, la viscosité volumique et la conductivité thermique, ainsi que leur rapport avec l'entropie volumique (s), tout en approchant la frontière conforme. Le but est d'analyser les effets d'un changement de l'échelle d'énergie au premier ordre des petits paramètres de la théorie. Ces résultats sont comparés aux résultats obtenus en utilisant la théorie conforme originale : cisaillement/s=1/4*pi et volumique/s=thermique/s=0. On observe que la viscosité de cisaillement change au premier ordre. Par contre, la viscosité volumique ne change pas au premier ordre. La conductivité thermique change en premier ordre, mais ce changement est multiplié par un paramètre libre. On peut introduire une coupure de l'échelle d'énergie dans la théorie pour fixer ce paramètre.

TRIUMF, Canada's national laboratory for nuclear and particle physics has been peering into the shape and structure of highly unstable, rare isotopes. Employing the method of collinear fast-beam laser spectroscopy, the nuclear ground state spin, hyperfine moments and charge radii can be determined. The laser spectroscopy group at TRIUMF has used this method to investigate the properties of rubidium isotopes, where 76-98 Rb had been previously studied at ISOLDE by Thibault et al. Laser spectroscopy was performed at TRIUMF on both the neutron deficient 74-76 Rb, providing insight into the behaviour leading up to the proton drip line. On the neutron rich end, a programme is in place to extend measurements into the highly deformed 98-100 Rb. Preliminary measurements of the spectra of the spin-0 isotope 92 Rb have been carried out, on beams with intensities of 10^7 per second, representing the first time heavy rubidiums have been produced and studied spectroscopically at TRIUMF. These measurements have been carried out in conjunction with the implementation of a new MCS based data acquisition system, greatly improving the data collection and analysis capabilities of the laser spectroscopy group. / TRIUMF, le laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules, a entrepris l'étude de la forme ainsi que la structure d'isotopes rares et hautement instables. En employant la méthode de la spectroscopie colinéaire utilisant des faisceaux atomiques à haute vitesse, le spin nucléaire ainsi que les moments nucléaires et le rayon de charge peuvent êtres determinés. Le groupe de spectroscopie au laser de TRIUMF a usé de cette méthode pour observer les propriétés fondamentales des isotopes du rubidium, famille isotopique pour laquelle les isotopes 76 Rb à 98 Rb ont déjà été étudiés au laboratoire ISOLDE par Thibault et al. En premier lieu, les isotopes déficitaires en neutrons 74 Rb - 76 Rb ont étés observés, permettant l'étude du rayon de charge nucléaire dans le régime menant à la ligne de limite de stabilité. Du côté riche en neutrons, un programme est en cours pour entreprendre l'étude des isotopes 98 Rb - 100 Rb, ces derniers étant hautement déformés. Des mesures péliminaires sur le spectre hyperfin de l'isotope 92 Rb, au spin nucleaire de 0, ont été réalisées, avec un rendement ionique de l'ordre de 10^7 par seconde. Ceci représente la première fois que des rubidiums lourds ont été produits et étudiés spectroscopiquement à TRIUMF. Ces nouvelles mesures ont été prises grâce à un nouveau système basé sur le principe d'un MCS, permettant l'augmentation de la capacité ainsi que de la qualité de l'acquisition de données.

The response of CsI photocathodes widely used in Fast RICH detectors is greatly affected by the environment in which the CsI is deposited. It has been shown in previous studies that the exposure of the CsI to air is detrimental to the CsI photocathode response. In this work we introduce a novel spraying technique where the whole chamber is exposed to nothing but a controlled dry argon atmosphere and the ambient gas environment in which measurements are taken, i.e., methane. All results concerning the CsI are obtained relative to copper. A relative quantum efficiency of 400 to 700 was measured in the wavelength range 170-180 nm. We also investigated the reproducibility of our measurements and estimated the CsI long wavelength cut-off to be approximately 213 nm. Finally, the deterioration of CsI photocathodes is studied when the chamber is sealed in a methane environment.

We present a calculation of $ Delta$ production cross section in the one-boson-exchange model for the reaction $NN to N Delta.$ Our calculation is in quantitative agreement with a previous calculation by Huber and Aichelin (1). The effect of the $NN to N Delta$ anisotropic differential cross section on $ pi$ production in Au + Au collisions at a kinetic energy of $1{GeV over A}$ is studied. We find that there is no large effect on the final $ pi$ transverse momentum spectra.

The technique of ion transfer in radio frequency quadrupole (RFQ) systems is described. Computer simulations of the gas filled RFQ mass filter system located at Argonne National Laboratory (ANL) in Argonne, Il. are performed and compared to data obtained from the transfer of radioactive ions produced from the fragmentation of an off-line 252Cf fission source put before the system. The device is used to transport radionuclides created in on-line fusion evaporation reactions from a 150 torr helium filled gas cell to a high vacuum mass spectrometer. Operation parameters and performance results for the gas filled RFQ mass filter system are presented. In addition, the first on-line transfer of a radioisotope resulting in a precise mass measurement using the Canadian Penning Trap (CPT) mass spectrometer is discussed.

In this dissertation, many-body physics techniques are used to study and improve ideas related to the description of heavy ion collisions at very high energy. The first part of the thesis concerns the production of tensor mesons in proton-proton (pp) collisions. An effective theory where the f2 meson couples to the energy-momentum tensor is proposed and a comparison of the inclusive cross-section computed in the collinear factorization, the kT-factorization and the color glass condensate is performed. A study of the phenomenology in pp collisions then shows a strong dependence on the parametrization of the unintegrated distribution function. The conclusion is that f2 meson production can be utilized to improve the understanding of the proton wave-function. In the second part, a similar investigation is performed by analysing the production cross-section of the eta' meson in pp and proton-nucleus (pA) collisions. The nucleus and proton are described by the CGC and the kT-factorization respectively. A new technique for the computation of Wilson lines - color charge densities correlators in the McLerran-Venugopalan model is developped. The phenomenology shows that the cross-section in pA collisions is very sensitive to the value of the saturation scale, a crucial ingredient of the CGC picture. In the third part of the thesis, the collision term of the Boltzmann equation is derived from first principles at all orders and for any number of participating particles, starting from the full out-of-equilibrium quantum field theory and using the multiple scattering expansion. Finally, the emission of photons from a non-abelian strong classical field is investigated. A formalism based on Schwinger-Keldysh propagators relating the production rate of photons to the retarded solution of the Dirac equation in a background field is presented. / Dans cette dissertation, les techniques de la physique à plusieurs corps sont utilisées afin d'étudier et d'améliorer certaines idées reliées à la description des collisions d'ions lourds à haute énergie. La première partie de cette thèse s'intéresse à la production des mésons tenseurs dans les collisions proton-proton (pp). Une théorie effective où le méson f2 couple avec le tenseur énergie-impulsion est proposée et une étude comparative de la section efficace calculée dans les formalismes de la factorisation colinéaire, de la factorisation-kT et du color glass condensate (CGC) est entreprise. La phénoménologie dans les collisions pp montre que la section efficace est très sensible à la paramétrisation des fonctions de distribution non-intégrées. En conséquence, la production de mésons f2 peut être utilisée pour améliorer notre compréhension de la fonction d'onde du proton. Dans la seconde partie, une investigation similaire est entreprise où la section efficace de production de mésons eta' est analysée dans les collisions pp et proton-noyau (pA). Le noyau et le proton sont décrits par le CGC et la factorisation-kT respectivement. Une nouvelle technique pour le calcul des correlateurs de lignes de Wilson - densités de charge de couleur dans le modèle de McLerran-Venugopalan est développée. La phénoménologie nous démontre ensuite que la section efficace dans les collisions pA est très sensible à la valeur de l'échelle de saturation, qui est un des éléments crucial dans l'approche du CGC. Dans la troisième partie de cette thèse, le terme de collision de l'équation de Boltzmann est dérivé à partir de principes premiers en utilisant l'expansion en collisions multiples. Finalement, l'émission de photons à partir d'un champs non-abélien classique fort est étudiée. Un formalisme basé sur les propagateurs de Schwinger-Keldysh et qui relie le taux de production des photons à la solution retardée de l'équa

An electrostatic decelerator system capable of bringing to rest a continuous 60 keV DC ion-beam was developed and tested as to its suitability as the first part of a high-performance RFQ buffer gas beam cooler. The decelerator is intended to decelerate high-energy ions for injection into an RFQ ion-guide capable of producing bunches of ions at a repetition rate up to 100 Hz. Simulations of the ion motion through the decelerator and into the guide were made to test the design, and the decelerator was then constructed following the parameters used in the simulations. Although problems, such as sparking between the electrode surfaces of the decelerator, prevented it from being operated at potentials high enough to decelerate a 60 keV beam, its implementation proved, as in the simulations, that high-energy ions could indeed be decelerated to energies that would allow for their injection into an RFQ ion-guide by this design.