Showing papers by "Chalk River Laboratories published in 1969"
557 citations
TL;DR: In this paper, Neutron inelastic scattering methods are used to demonstrate the close connection between the antiferroelectric phase transition at 110°K in SrTiO 3 and the temperature dependence of the triply degenerate Γ 25 mode of vibration of wave vector.
124 citations
TL;DR: In this paper, the channeling characteristics of protons and helium ions in various diamond-type lattices (diamond, Si, Ge, GaP, GaAs, and GaSb) have been studied by means of Rutherford backscattering in the 0.5-2-MeV range.
Abstract: The channeling characteristics of protons and helium ions in various diamond-type lattices (diamond, Si, Ge, GaP, GaAs, and GaSb) have been studied by means of Rutherford backscattering in the 0.5-2-MeV range. Critical angles (${\ensuremath{\psi}}_{\frac{1}{2}}$) and minimum yields (${\ensuremath{\chi}}_{min}$) have been measured and compared to theory. The values of ${\ensuremath{\psi}}_{\frac{1}{2}}$ for axial channeling have a functional dependence which agrees well with calculations based on the average potential along the row---both for uniform and for nonuniform spacing and (in the case of the compound semiconductors) for mixed atomic composition. However, the measured values are \ensuremath{\approx} 25% lower in absolute magnitude. Planar critical angles show a faster attenuation with decreasing planar spacing than predicted, but in other aspects agree with theory. In the compound semiconductors, the orientation dependence of backscattering and of x-ray yields has been used to investigate simultaneously the interaction of the beam with both atomic species in the lattice. For those directions along which the different atomic species lie on separate rows (e.g., $〈110〉$), each row steers the incident particles in a manner described by the average potential of that row.
106 citations
TL;DR: In this paper, the authors used a mercury porosimeter to measure the size distribution of cracks and pores in insulating oxide films, with an electron microscope study of the same oxide films.
79 citations
TL;DR: In this paper, a truncation of the complete vector space is proposed for low-lying eigenvalues and eigenfunctions in the shell model, where a properly chosen initial vector is operated upon iteratively, generating a basis in which the Hamiltonian matrix is tridiagonal.
40 citations
TL;DR: In this article, a particle identification method, in which an experimental range-energy relation is stored in the computer memory, was proposed, which is relatively fast and potentially more selective than analogue devices.
34 citations
TL;DR: In this article, the performance of Compton spectrometers using two Ge(Li) gamma-ray detectors is demonstrated and two different configurations of detectors have been used, together with on-line computer methods to show that a nearly single-peak spectrum of good resolution can be obtained for a monochromatic gamma ray.
28 citations
TL;DR: In this paper, an electron probe microanalyzer was used to investigate the niobium content of the OL and transformed p phases in a Zr-2.5% Nb alloy and to determine the location of the a/(& +@) phase boundary.
28 citations
TL;DR: In this article, a comparison between wide-angle scattering and x-ray yield curves is reported for tungsten single crystals with respect to an incident beam of 1.4-MeV helium ions.
Abstract: Measurements of wide-angle (150\ifmmode^\circ\else\textdegree\fi{}) scattering and of $L$ and $M$ x-ray yields in tungsten single crystals are reported as a function of crystallographic orientation with respect to an incident beam of 1.4-MeV helium ions. Comparison of these yields establishes both lower and upper limits for the minimum impact parameter (${r}_{min}$) between a channeled ion and the tungsten-lattice atoms; these limits are consistent with Lindhard's estimate that ${r}_{min}\ensuremath{\sim}\mathrm{a}$, the Thomas-Fermi screening distance (i.e.,\ensuremath{\sim}0.11 \AA{} for He in W). A similar comparison between wide-angle scattering and x-ray yield curves is reported for several other lattices\char22{}Al, Si, GaP, GaSb, and U${\mathrm{O}}_{2}$; again the results are consistent with the predicted relationship: ${r}_{min}\ensuremath{\sim}\mathrm{a}$. Anomalies in published orientation studies of $K$, $L$, and $M$ x-ray yields are shown to be due to depth effects.
24 citations
TL;DR: In this paper, the lattice location of the implanted atoms has been determined by means of the channeling technique, and high substitutional components have been observed in Bi and TI implants in silicon without any annealing treatment.
Abstract: High substitutional components have been observed in Bi and TI implants in silicon without any annealing treatment. Implant conditions were ∼1013 ions/cm2 at 40keV and 25 °C. The lattice location of the implanted atoms has been determined by means of the “channeling” technique.
16 citations
TL;DR: In this paper, the K-conversion electron intensities of transitions in 154 Gd with strong E0 components have been measured at 0.1% resolution in momentum, and the transitions of 692.41, 680.70 and 676.58 keV are observed from the 0 +, 2 + and 4 + members of the β-vibrational band to levels with the same spin in the ground state band.
TL;DR: In this paper, the Coulomb excitation of 127 I with 16 O projectiles in the range 35-55 MeV was studied, and three new levels were found, and spin assignments were made for some previously known levels.
TL;DR: In this paper, a new form of the two-body potential has been investigated for its possible applications in nuclear calculations, which can be applied with confidence to Hartree-Fock calculations of finite nuclei.
Abstract: A new form of the two-body potential recently proposed has been investigated for its possible applications in nuclear calculations. This nonsingular force, chosen for its success in fitting scattering phase shifts, saturates nuclear matter at the correct energy and density, and yields small second-order corrections. It can thus be applied with confidence to Hartree-Fock calculations of finite nuclei. We study the closed-shell nuclei16O and40Ca and show that many of their basic properties can be reasonably predicted.
TL;DR: In this paper, a simple projection operator K is introduced that projects spurious states from a general harmonic oscillator shell model state to minimize the contributions of spurious states to low energy states in truncated bases.
TL;DR: In this paper, necessary and sufficient conditions for the simultaneous matching by a quadrupole lens of the phase-space ellipses corresponding to motions in two orthogonal directions perpendicular to the beam direction are derived.
TL;DR: The Survey Meter as discussed by the authors measures?-ray dose rates from background up to 20 rad/hour, with an energy range from 30 keV to 1.25 MeV, and it can be used to measure the amount of radiation reaching the detector.
Abstract: The Survey Meter measures ?-ray dose rates from background up to 20 rad/hour. The ?-ray energy range is from 30 keV to 1.25 MeV. Amplifying detectors which avalanche between 500 and 2000 volts are acceptable. The paper describes the circuits, mechanical design and its performance.
TL;DR: In this paper, the effect of a singleparticle (s · l ) force in 20 Ne is shown to admix only a few representations of SU 3 independently of the strength, which strongly suggests a collective mode and a useful truncation of the shell-model configurations.