Several investigations involving strongly interacting matter at high temperature and density are pursued. First concentrating on relativistic heavy ion collisions slightly below the GeV/nucleon range, we perform studies of the equation of state (EOS) for nuclear matter. The non-equilibrium aspects of such collisions are simulated by the Boltzmann-Uehling-Uhlenbeck transport model with a momentum-dependent nuclear mean field. The EOS effects on the collective flow observables and dielectron spectra have been systematically and quantitatively examined by comparing with the experimental data gathered by the DIOGENE, Streamer Chamber, Plastic Ball, EOS TPC, E848H and DLS collaborations. The importance of the precise functional dependence of the nuclear mean field on the particle momentum, and the compressibility coefficient K of the nuclear matter are addressed. Using a simple coalescence model, we show that a quantitative connection between the composite flow and K can be established. In such nucleus-nucleus collisions, we also consider and discuss lepton pair production mechanisms. These include nucleon-nucleon bremsstrahlung, $ Delta$ decay, $ eta$ decay, and pion-pion annihilation. We then turn to lepton pair production in ultrarelativistic heavy ion collisions. We concentrate on pion-pion virtual bremsstrahlung in the soft limit M $<$ 300 MeV, and we make a quantitative comparison of various soft-photon-approximation (SPA) formulae with a full one-boson-exchange (OBE) calculation.

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.

No description available.

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.