A novel approach is proposed for studying the ν(μ) → ν(τ) oscillation and detection of extragalactic neutrinos. Active Galactic Nuclei (AGN), Gamma Ray Bursters (GRB) and Topological Defects are believed to be sources of ultrahigh energy ν(μ) and νₑ. These astrophysical sources provide a long baseline of 100Mpc, or more, for possible detection of ν(μ) → ν(τ) oscillation with mixing parameter Δm² down to 10⁻¹⁷ eV², many orders of magnitude below the current accelerator experiments. The propagation characteristics of upward going muon and tau neutrinos is studied to show that high energy tau neutrinos cascade down in energy as they propagate through the Earth, producing an enhancement of the incoming tau neutrino flux in the low energy region. By contrast, high energy muon neutrinos get attenuated as they traverse the Earth. It is observed that the relative steepness of the incoming neutrino flux spectrum and the nadir angle of the Earth are two important factors that influence the enhancement and cascade of nutau flux. This effect provides a novel way to search for tau neutrino appearance by measuring the angular dependence of tau neutrino induced upward muons; and upward hadronic and electromagnetic showers. A Monte Carlo evaluation of tau survival probability and its range shows that at energies below 10⁷ - 10⁸ GeV, depending on the material, only tau decays are important. However, at higher energies the tau energy losses are significant, hence reducing the survival probability of tau. Here, tau energy loss for energies up to 10⁹ GeV have been calculated taking into consideration the decay of tau. An understanding of tau energy loss at very high energies could help with the interpretation of long tracks produced by charged particles in large underground detectors.

This study involves the measurement of the neutron equivalent dose ( NED) and the induced activity produced from medical linear accelerators. For the NED, various parameters such as the profile, field effects and energy responses were studied. The NED in a Solid Water(TM) phantom was measured and a new quantity, the neutron equivalent dose tissue-air ratio (NTAR), was defined and determined. Neutron production for electron beams was also measured. For the induced activity, comparisons were carried out between different linacs, fields and dose rates. The half life and activation saturation were also studied. A mathematical model of induced activity was developed to explain the experimental results. Room surveys of NED and induced activity were performed in and around a high energy linear accelerator room. Unwanted doses from photoneutrons and induced activity to the high energy linear accelerator radiotherapy staff and patient were estimated.

Low Temperature Nuclear Orientation (LTNO) is an important technique in the study of nuclei far from stability. The theory of LTNO and its applications to the measurement of static nuclear moments and other quantities of spectroscopic interest are reviewed. Among the nuclei off the line of stability those in the A ~ 75 region are of considerable interest, exhibiting large quadrupole deformations, triaxiality and shape coexistence. LTNO measurements performed on neutron deficient bromine isotopes have yielded the static magnetic dipole moments of the nuclei <sup>72g,72m,74m,75,76,77<sup>Br, Spectroscopic information on ^72-77Se and also identified the ground state spin of ⁷³Br as l/2‾ Existing odd A and odd-odd particle-rotor computer codes have been extended in order to include a Variable Moment of Inertia (VMI) asymmetric rotational core. The formalism necessary for this modification is developed. The measured magnetic moments are interpreted within the framework of this particle - VMI rotor model. It is shown that the systematic reduction in the moments of the odd A nuclei ^75-81Br characterizes the transformation of the prolate ground state configuration from largely π[301]3/2 in ^79,81Br to almost pure π[312]3/2 in ^75,77Br. This trend is fully consistent with the increase in deformation towards the lower masses suggested by the known electric quadrupole moments. In contrast, the ground state spin of ⁷³Br can only be interpreted in terms of an oblate nuclear shape. This is the first evidence for the predicted prolate-oblate shape transition in the bromine nuclei. In addition the magnetic moment of ⁷⁴Br^m, by identifying a π[431]3/2ν[422]5/2 configuration, strongly suggests a positive parity assignment for the isomeric state. Finally, an experiment to search for possible T-violation effects in nuclear gamma decay is described. Using coincidence techniques, a measurement of the T-odd P-even quantity (I ‧ k x e)(I ‧ k)(I ‧ e) has lead to a limit on the T-violating phase angle between the E2 and Ml matrix elements associated with the 604 keV gamma transition in ¹⁹²Pt of sin η = ±11(12) x 10^-3.

The subject of this thesis is the production of electromagnetic radiations during relativistic heavy ions collisions. Since they constitute one of the major ways to probe the presence of a quark-gluon plasma (QGP), their evaluation through theoretical models is very important. The photon production at low-to intermediate transverse momentum (pT) is first studied. The photon production rate in a mesonic gas is evaluated within a massive Yang-Mills (MYM) approach. Earlier calculations are reexamined with additional constraints, including new production channels and with the inclusion of form-factors. Adding primordial N-N contribution and existing baryonic and QGP production rates, we can reproduce the photon spectra observed at the Super Proton Synchrotron (SPS). The intermediate to high-p T region is dominated by the physics of jets. A treatment, complete to leading-order in the strong coupling, is used to calculate energy loss in the strongly interacting medium. This approach is convolved with a physical description of the initial spatial distribution of jets and with an expansion of the emission zone. The role played by jet-plasma interactions is highlighted, showing that they dominate in the range 2 &lt; p T &lt; 4 GeV, at the Relativistic Heavy Ion Collider (RHIC). This mechanism has an important impact on both the total photon yield and the photon azimuthal asymmetry, turning the coefficient v 2 negative. Finally, the dilepton production at high p T is calculated with hard-thermal loops (HTL) effects, showing, that in perfect analogy with real photons, jet-plasma interactions also dominate the dilepton yield around pT = 4 GeV.

Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 83-94). Also available via World Wide Web.

Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 241-264). Also available via World Wide Web.

Thesis (Ph. D.)--Leiden Rijksuniversiteit, 1971. / Vita. Summaries in English and Dutch. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (p. 141-150).

Thesis (M.S.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

No description available.