Different roles for internal standards in PIXE analysis of fluid residues are discussed. The efficacy of internal standards is predicated on having homogeneous targets of uniform thickness; the use of lecithin additiv...
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Different roles for internal standards in PIXE analysis of fluid residues are discussed. The efficacy of internal standards is predicated on having homogeneous targets of uniform thickness; the use of lecithin additives to achieve this is described and data are presented to illustrate the dependence of analytical precision on the mode of specimen preparation. Determination of actual thickness via measurement of the energy loss of transmitted protons is demonstrated; this provides a means of correcting for departures from the much-quoted “thin target” criterion.
Monoenergetic X-ray lines produced by diffraction from a curved crystal monochromator have been used to test the applicability of the Hypermet function for Si(Li) detectors. Excellent fits are achieved; the function&#...
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Monoenergetic X-ray lines produced by diffraction from a curved crystal monochromator have been used to test the applicability of the Hypermet function for Si(Li) detectors. Excellent fits are achieved; the function's parameters vary smoothly with energy, and the intensity of the non-Gaussian peak components correlates with the thickness of the frontal dead layer where charge collection is incomplete. Accurate silicon escape peak intensities are presented and the contribution to the lineshape from Compton-scattered events is discussed qualitatively.
The first results of the analysis of bitumen and oil sands using the recently developed n.m.r. spingrouping technique are presented. The n.m.r. relaxation experiments were carried out on bitumen, and on natural and dr...
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The first results of the analysis of bitumen and oil sands using the recently developed n.m.r. spingrouping technique are presented. The n.m.r. relaxation experiments were carried out on bitumen, and on natural and dried oil sands samples. The results indicate that the spin-grouping can resolve and quantify several components of the samples studied. The bitumen and bitumen fraction of the oil sands are resolved according to their spin-spin relaxation times into three major groups: solid-like (rigid), solid-like (mobile) and semi-liquid. The water in the oil sands exists in two different environments. Tentatively one environment is assigned to be the bridges between the sand grains, while the other is assigned to be the clay surface. One can conclude that with spin grouping of complex mixtures the decomposition (in which components are resolved according to their dynamic state) is possible. The accuracy of such resolution is of the order of a few per cent.
Electronic insulating solids are divided into 4 distinct categories on the basis of their different positron-transport properties. Of the 8 types of material tested, 5 were positronic as well as electronic insulators ...
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Electronic insulating solids are divided into 4 distinct categories on the basis of their different positron-transport properties. Of the 8 types of material tested, 5 were positronic as well as electronic insulators but positron mobilities ranged up to 102 cm 2 /v.s. - in paraffin wax. Striking qualitative differences in the fraction of positronium decays, and its dependence on electric field strength, supplement the mobility data in defining the different categories.
It is demonstrated that the non-linear effects in the indirect ion-ion interaction, via the valence electrons, are primarily responsible for the anomalous features present in the observed S ( q )'s of In and Tl bu...
It is demonstrated that the non-linear effects in the indirect ion-ion interaction, via the valence electrons, are primarily responsible for the anomalous features present in the observed S ( q )'s of In and Tl but are responsible to a much lesser extent for those in Ga, Sn and Bi.
作者：
ISENOR, NRUniversity of Waterloo
Guelph-Waterloo Program for Graduate Work in Physics Centrefor Molecular Beams and Laser Chemistry Waterloo Ontario N2L 3G1.
The observation of a distortion of the β spectrum of tritium is reported. This distortion is consistent with the emission of a neutrino of mass about 17.1 keV and a mixing probability of 3%.
The observation of a distortion of the β spectrum of tritium is reported. This distortion is consistent with the emission of a neutrino of mass about 17.1 keV and a mixing probability of 3%.
A theory of reference-plane positions for the substrate-mediated dispersion energies is presented. It is found that two reference-plane positions, Z1 and Z2, are required for the description of the interference and im...
A theory of reference-plane positions for the substrate-mediated dispersion energies is presented. It is found that two reference-plane positions, Z1 and Z2, are required for the description of the interference and image interactions between two atoms (molecules) in the presence of a surface. Model calculations for Z1, Z2, and other dispersion coefficients are presented for a number of adsorption species on jellium and noble-metal substrates.
The Privman-Fisher hypothesis on the singular part of the free-energy density of a finite system, near the bulk critical point T=Tc, is examined in the context of an ideal relativistic Bose gas confined to a cuboidal ...
The Privman-Fisher hypothesis on the singular part of the free-energy density of a finite system, near the bulk critical point T=Tc, is examined in the context of an ideal relativistic Bose gas confined to a cuboidal enclosure (L1×L2×L3) under periodic boundary conditions. Taking into account the possibility of particle-antiparticle pair production in the system, explicit expressions are derived for the free energy, the specific heat, and the condensate density at temperatures close to Tc, and the special cases of a cube, a square channel and a film are investigated at length. The various predictions of the Privman-Fisher hypothesis are fully borne out and the scaling functions governing the critical behavior of the system are found to be universal—irrespective of the severity of the relativistic effects. The influence of the latter enters only through the nonuniversal scale factors, C1 and C2, which depend on the particle mass m and density ρ as well.
The results of the protonrelaxation time dispersion measurements on Ge(CH3)4 at temperatures below 26 K show that the maximum of the T ?1 ZT dispersion curve decreased and the linewidth increases as the temperature is...
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The results of the protonrelaxation time dispersion measurements on Ge(CH3)4 at temperatures below 26 K show that the maximum of the T ?1ZT dispersion curve decreased and the linewidth increases as the temperature is decreased. This cannot be accounted for by any version of the correlation function perturbation approach which at low temperatures, on tunneling resonance nω0=ω t gives a relaxation rate proportional to the correlation time. However if the tunnelinglinewidth is due to the torsion–torsion interaction—which is averaged out at higher temperatures—the observed behavior is explained. From the observed low temperature tunnelinglinewidth the torsion–torsion interaction in this material is estimated to be 30 MHz. The results of multipulse saturation sequence measurments at the maximum of the T ?1ZT dispersion curve are presented and discussed in terms of a population‐transfer model.
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