Atomic Energy of Canada Limited

About: Atomic Energy of Canada Limited is a company organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Zirconium alloy & Neutron. The organization has 4845 authors who have published 4826 publications receiving 102951 citations.

Atomic Distribution in Liquid Argon by Neutron Diffraction and the Cross Sections of A 36 and A 40

Abstract: The angular distribution of 1.04 A neutrons scattered by liquid argon at 84\ifmmode^\circ\else\textdegree\fi{}K is reported. Small-angle scattering in the pattern is accounted for in terms of isotope incoherence using the same sign for the measured values of the scattering lengths of ${\mathrm{A}}^{40}$ and ${\mathrm{A}}^{36}$. The transmission cross section of ${\mathrm{A}}^{36}$ was measured for 1.04 A neutrons and found to be 77\ifmmode\pm\else\textpm\fi{}9 barns corresponding to a scattering cross section of 73\ifmmode\pm\else\textpm\fi{}9 barns. The scattering cross section of ${\mathrm{A}}^{40}$ was measured and found to be 0.36 barn. The scattering curve was transformed to the atomic density distribution $4\ensuremath{\pi}{r}^{2}[\ensuremath{\rho}(r)\ensuremath{-}{\ensuremath{\rho}}_{0}]$ for the liquid. The function shows only small oscillations about $\ensuremath{-}4\ensuremath{\pi}{r}^{2}{\ensuremath{\rho}}_{0}$ for spacings out to 3 A. Beyond this the curve oscillates about zero with an amplitude which decreases with increasing radius. The number of neighbors assigned to the first shell of atoms is ${8.}_{2}$. From a comparison of the position of the density cutoff and first density maximum with that expected for a Lennard-Jones 12:6 potential, it is concluded that the effective potential in the liquid has a broader bowl than that given by the Lennard-Jones 12:6 potential.

Radiosensitization of mammalian cells by p-nitroacetophenone. I. Characterization in asynchronous and synchronous populations.

Abstract: SummaryThe effectiveness of p-nitroacetophenone (PNAP) as a sensitizing agent to x-rays has been measured in asynchronous and synchronous populations of Chinese hamster cells. PNAP was found to sensitize hypoxic cells selectively (those equilibrated with an environment of 96 per cent N2 + 4 per cent CO2 containing less than 2 p.p.m. O2) with a maximum dose-modifying factor (DMF) of ∼ 1·50 at concentrations of 400 µM and greater in complete medium. In a parallel radiation scheme, the DMF for cells saturated with air was consistently between 2·75 and 3·05. In synchronously-growing Chinese hamster cells, the cyclic variation in surviving fraction measured for cells in air experiencing a radiation dose of 1055 rads could be reproduced for cells irradiated in hypoxic conditions with 2840 rads. We conclude that O2 sensitizes Chinese hamster cells in a dose-modifying fashion, irrespective of position in the cell-cycle. Hypoxic synchronized cells irradiated in the presence of PNAP with 1980 rads are also sensitiz...