[en] The ¹²C(¹²C,p) reaction, at a bombarding energy of 39.0 MeV, has been used to locate candidates for high-spin states. Angular distributions and angle-integrated cross sections are presented for 43 levels (or groups of levels) of which at least 10 probably have J> or =(9/2). .AE

[en] In the 1990s, representatives from the Saskatchewan uranium industry and the seven indigenous bands and communities living in the Athabasca region of northern Saskatchewan formed the Athabasca Working Group (AWG) and signed one of Canada's first Impact Management Agreements. In the agreement, the companies committed to providing compensation for losses of specified resources that could be attributed to emissions from uranium projects. The AWG established an environmental monitoring programme to act as the primary method for assessing whether a loss had occurred. A key element of the monitoring programme is community involvement, which includes community members deciding what environmental components to sample, where to collect the samples and taking part in the sample collections. An independent consultant helps coordinate the programme and presents the results to each community in a user-friendly format. The AWG environmental monitoring programme is currently in its fifth consecutive year of operation and it continues to be an important programme to help build relations between indigenous groups and the uranium mining industry in northern Saskatchewan. (author)

[en] We investigate the one- to two-dimensional zigzag transition in clusters consisting of a small number of particles interacting through a Yukawa (Debye) potential and confined in a two-dimensional biharmonic potential well. Dusty (complex) plasma clusters with n≤19 monodisperse particles are characterized experimentally for two different confining wells. The well anisotropy is accurately measured, and the Debye shielding parameter is determined from the longitudinal breathing frequency. Debye shielding is shown to be important. A model for this system is used to predict equilibrium particle configurations. The experiment and model exhibit excellent agreement. The critical value of n for the zigzag transition is found to be less than that predicted for an unshielded Coulomb interaction. The zigzag transition is shown to behave as a continuous phase transition from a one-dimensional to a two-dimensional state, where the state variables are the number of particles, the well anisotropy and the Debye shielding parameter. A universal critical exponent for the zigzag transition is identified for transitions caused by varying the Debye shielding parameter.

[en] Autoradiography is a widely used technique for imaging trace quantities of radioactivity within biological samples, conventionally using photographic film. This method produces images with high spatial resolution, but it suffers from very low sensitivity and poor dynamic range. Digital autoradiography systems with greatly improved sensitivity and linearity are commercially available, but the spatial resolution is usually much less than that achieved using film. We report here the design, construction and characterization of a novel digital autoradiography system based on scientific-grade charged coupled devices (CCDs). Images of x-ray and β emissions from radionuclides commonly used in autoradiography show that the system can perform high-speed quantitative imaging with a spatial resolution of ∼30 μm. Using a frame by frame acquisition method the dynamic range is shown to be at least three orders of magnitude. The absolute detection efficiency is comparable to the best of the currently available digital systems. CCD images of ¹²⁵I and ¹⁴C radioisotope distributions in tissue samples are superior to the equivalent film images and have been acquired in 1-10% of the time. (author)

[en] A digital tissue imaging system based on a cooled charge coupled device (CCD) has been developed at the Physics Department of the Institute of Cancer Research. The system images low energy X-ray emissions and β particle emissions from a variety of isotopes, with a position resolution approaching 20μm and sensitivity approaching 100%. Because of the frame-by-frame composite way in which images are constructed, the dynamic range of the system is 16 bit, limited only by the microcomputer used to acquire and store the images. Images have been obtained of isotope distributions in tissue with radioactivity levels which were too low to be detected using conventional technology. Room temperature operation of the CCD in the inverted mode has been investigated

[en] A method for measuring the time-averaged vertical electric field and its gradient in the plasma sheath using clusters with n=2 or 3 floating microspheres of known mass is described. The particle charge q is found by determining the ratio of the breathing frequency to the center-of-mass frequency for horizontal (in-plane) oscillations. The electric field at the position of the particles is then calculated using the measured charge-to-mass ratio, and the electric-field gradient is determined from the vertical resonance frequency. The Debye length is also found. Experimental results are in agreement with a simple sheath model

[en] The use of simulators by the Royal Navy for training personnel in realtime operations in nuclear submarines is discussed. A typical Manoeuvring Room Training Simulator complex consisting of the manoeuvring room, the instructor's console and the computer interfaces, is described. Advantages, and drawbacks of simulator training and the role of the simulator in operator training are considered. The experience gained from the use of simulators over the last decade for the purpose of training Royal Navy Manoeuvring Room watchkeepers on nuclear submarines is examined. (U.K.)

[en] An elliptical Debye cluster is a system of n identical charged particles interacting through a screened Coulomb potential and confined in a two-dimensional anisotropic parabolic well. A model for this system has been developed with three parameters: n, the well anisotropy α², and the Debye shielding parameter κ. From numerical solutions of the model, it is shown that the breathing mode persists as the anisotropy increases, and that the normalized, squared breathing frequency increases linearly with α². Elliptical clusters with n=49 and 15 particles were studied experimentally. The anisotropic potential well was created using a rectangular aperture (17.5x30.2 mm) placed on a flat electrode. The well anisotropy was determined by measuring the center-of-mass (c.m.) oscillation frequencies along the major and minor axes of the resulting elliptical clusters using both driven and thermal oscillations. The two methods give results that are in good agreement. For n=49 particles, the square of the ratios of the c.m. frequencies was α²=2.9±0.1. From a measurement of the breathing frequency, the shielding parameter was found to be κ=2.1±0.2. For n=15 particles, α²=2.8±0.1 and κ=1.9±0.2, demonstrating that an analysis using the model gives consistent results

[en] The design and construction of the first of two BaF₂-TMAE large area detectors to be incorporated in a unique double headed whole body PET system (PETRRA) has been completed. Preliminary experimental work carried out with the first large area detector shows an absolute detection efficiency of 20.5% and a time resolution of 3.5ns (FWHM) and 8.0ns (FWTM), using 8mm thick scintillation crystals. An analytical model of the electronic read-out system has been developed to investigate the rate capability of the new scanner. This model predicts that under typical imaging conditions, with 40MBq of activity in the field of view, the proposed scanner will acquire coincidence data at 20--25kcps

[en] The Beaverlodge uranium mining and milling facility, located near Uranium City in northern Saskatchewan, operated for a period of thirty-two years between 1950 and 1982, making it one of the longest operating facilities of its type in Canada. Ore was extracted from the ma in underground mine and from smaller underground and open pit satellite deposits in a ratio of 94% and 6% respectively. Decommissioning activities consisted of four phases, shutdown, salvage and reclamation which occurred from 1982-1985, and the current transition monitoring phase from 1985 to present. Following transition monitoring to prove that the system is behaving as expected, licence revocation and hence completion of decommissioning is expected to occur. The plan to achieve delicensing from the federal Canadian Nuclear Safety Commission and surface lease revocation from the provincial government is currently captured in a 10-year plan, 2003-2013. The main remaining objective of the decommissioning plan is to document the aquatic ecosystem recovery of the former tailings management facility (TMF), which consisted of two natural lakes, and of the two former underground satellite areas, Hab and Dubyna. Extensive environmental monitoring has been carried out in the receiving environment, Beaverlodge Lake, the former Dubyna mine area and the TMF. Recovery of the aquatic ecosystems is occurring within an environment containing above-background levels of natural radionuclides. This makes Beaverlodge, with its relatively clean ore and long history of natural recovery, one of the better places to study low-level radioactive environmental biological effects. The Dubyna area has above background uranium concentrations in the water, sediment and fish, and a benthic invertebrate community similar to reference. In the receiving environment, Beaverlodge Lake, metal concentrations are highest with the deeper sediment. This trend fits well with the increased impacts of 32-years of operation followed by reduced impact in 20-years of transition. The assessment of ecosystem recovery and other aspects of the delicensing and surface lease revocation, allows for reflection on 'lessons learned,' from operational procedures as defined by the standards of the time and decommissioning activities carried out to date. This paper documents the recovery of the aquatic ecosystems impacted during the operating phase, comparing the data to reference areas and current criteria. In addition, lessons learned for consideration by current operations are reviewed. (author)