[en] High Efficiency Particulate Air filtration is an essential component of the containment and ventilation systems supporting the research and development activities at the Oak Ridge National Laboratory. High Efficiency Particulate Air filters range in size from 7.6cm (3 inch) by 10.2 cm (4 inch) cylindrical shape filters to filter array assemblies up to 2.1 m (7 feet) high by 1.5 m (5 feet) wide. Spent filters are grouped by contaminates trapped in the filter media and become one of the components in the respective waste stream. Waste minimization and pollution prevention efforts are applied for both radiological and non-radiological applications. Radiological applications include laboratory hoods, glove boxes, and hot cells. High Efficiency Particulate Air filters also are generated from intake or pre-filtering applications, decontamination activities, and asbestos abatement applications. The disposal avenues include sanitary/industrial waste, Resource Conservation and Recovery Act and Toxic Substance Control Act, regulated waste, solid low-level waste, contact handled transuranic, and remote handled transuranic waste. This paper discusses characterization and operational experiences associated with the disposal of the spent filters across multiple applications

[en] The first part of this thesis considers many-body effects in the thermodynamic properties of Fermi liquids and of the electron-phonon system. Using normal liquid ³He as an example, it is shown that T³InT corrections due to spin fluctuations account for finite-temperature corrections to the leading term in the specific heat. Also calculated and compared are the statistical and the dynamical quasiparticle spectra; it is shown that differences between them partially account for the discrepancy between these and previous results. Spin-fluctuation parameters determined from fits to specific heat of UPt₃ and UAl₂ are examined, and applicability of simple spin-fluctuation models to these systems is discussed. In addition, the author considers the T³InT contributions to the specific heat of metals due to the electron-phonon coupling and shows how they may be viewed as being analogous to those from spin fluctuations. In the second part of the thesis, he reviews the application of polarization potential theory to the description of the excitations of liquid ⁴He at low temperature and uses recent experimental results to determine the parameters in the theory. He calculates the dispersion curve in the absence of dynamic mode-mode coupling and discusses the results

[en] Superconductivity has been successfully described with either the Landau-Ginzburg theory of second order phase transitions or with strong-coupling versions of the original BCS theory for almost fifty years. Recent tunneling and photoemission data on the cuprate oxide superconductors may now provide evidence of corrections to the mean field approximation. It has been shown by Zasadzinski et al. that there is a dip at eV ≅ 3Δ₀ in the SIS tunneling conductance, which is the derivative of the current across a superconductor-insulator-superconductor junction with respect to the applied voltage, for a set of cuprate superconductors whose T_c's range from 5.5K to 100K. Recently L. Coffey and I proposed an explanation of this feature in terms of the spontaneous decay of mean field quasiparticles. We showed that corrections to the mean field approximation for a superconductor lead to different frequency thresholds for spontaneous quasiparticle decay with different superconductor order parameter symmetries. These effects lead to features in the superconductor density of states and in the SIS tunneling conductance and provide experimental evidence of d-wave symmetry for the superconductor order parameter in the cuprates. I discuss model and also evidence of quasiparticle decay in ARPES data on Bi₂Sr₂CaCu₂O₈

[en] We compare the self-energy and entropy of a two- and three-dimensional Fermi Liquids (FLs) using a model with a contact interaction between fermions. For a two-dimensional (2D) FL we find that there are T² contributions to the entropy from interactions separate from those due to the collective modes. These T² contributions arise from nonanalytic corrections to the real part of the self-energy and areanalogous to T³lnT contributions present in the entropy of a three-dimensional (3D) FL. The difference between the 2D and 3D results arises solely from the different phase space factors

[en] Tsuei et al. have pointed out that the correlation between a maximium in T_c and a minimum in the oxygen isotope exponent, α, observed by Crawford et al. in La_2-xSr_xCuO₄ and by Franck et al. in (Y_1-xPr_x)Ba₂Cu₃O₇ may be understood as a carrier density of states effect, N(E). We point out here that, if the gap equation is treated in the weak coupling approximation, an N(E) with an enhancement in a narrow range of energies which is symmetric about some energy E_s is sufficient to give the correlation. We discuss how such as enhancement may arise from a tight-binding description of the CuO planes

[en] This paper describes the waste characteristics of newly generated transuranic waste from the Radiochemical Engineering and Development Center at the Oak Ridge National Laboratory and the basic certification structure that will be proposed by the University of Tennessee-Battelle and Bechtel Jacobs Company LLC to the Waste Isolation Pilot Plant for this waste stream. The characterization approach uses information derived from the active production operations as acceptable knowledge for the Radiochemical Engineering and Development Center transuranic waste. The characterization approach includes smear data taken from processing and waste staging hot cells, as well as analytical data on product and liquid waste streams going to liquid waste disposal. Bechtel Jacobs Company and University of Tennessee-Battelle are currently developing the elements of a Waste Isolation Pilot Plant-compliant program with a plan to be certified by the Waste Isolation Pilot Plant for shipment of newly generated transuranic waste in the next few years. The current activities include developing interface plans, program documents, and waste stream specific procedures

[en] I investigate the difference between the quasiparticle properties in two-dimensional (2D) and three-dimensional (3D) S-wave superconductors. Using the original BCS model for the pairing interaction and direct Coulomb interaction I show that quasiparticle interactions lead to a stronger energy dependence in the single-particle self-energies in 2D than in 3D superconductors. This difference arises from the presence of the low-lying collective mode of the order parameter in the 2D case which ensures that oscillator strength in the response function is at low frequencies, ∝Δ. This strong quantitative difference between 2D and 3D superconductors points to the importance of treating quasiparticle interactions in low-dimensional superconductors rather than assuming that renormalizations remain unchanged from the normal state. (orig.)

[en] We show that the effective spin Hamiltonian used previously to describe the CuO planes of La₂CuO₄ does not lead to a net ferromagnetic moment for CuO planes and hence does not describe the metamagnetic behavior seen experimentally. We construct for the first time a Hamiltonian from the symmetries of the crystal structure which does lead to metamagnetism. The linear spin-wave spectrum is also calculated. This work points to the necessity of constructing effective spin Hamiltonians for metamagnetic systems which have the same symmetries as the system they are to describe

[en] La₂CuO₄ is an S=1/2 system with almost tetragonal symmetry so that there is no single-site interaction term giving rise to anisotropy and the magnetic anisotropy of the system can be explained in terms of the Dzyaloshinskii--Moriya interaction which can lead to weak ferromagnetism even in a system with predominantly antiferromagnetic interactions. However, the closely related compounds, La₂NiO₄ and La₂CoO₄, are S=1 and S=3/2 systems, respectively, so that a single-site interaction term is present and it is of interest to see how this interaction changes the magnetic properties of these compounds. Here the classical magnetic ground states are calculated for model Hamiltonians, appropriate to the different low-temperature structural phases of the compounds, containing both interactions

[en] Interactions in La₂CuO₄ are predominantly antiferromagnetic. However, a strong field-induced transition is seen in the static magnetic susceptibility which points to the existence of a net ferromagnetic moment in the CuO layers. Here, this net ferromagnetic moment is incorporated into a description of the CuO layers by the inclusion of a modified Dzyaloshinskii--Moriya term in the Hamiltonian. The spin-wave spectrum in the presence of an applied field is calculated with this Hamiltonian and the ground state is determined as a function of applied field from the free energy. A calculation of the static magnetization as a function of applied field perpendicular to the CuO layers is used to determine the parameters of the model. Comparison is made with experiment