Radiation hardness qualification of PbWO4 scintillation crystals for the CMS Electromagnetic Calorimeter

This is the Pre-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2010 IOPEnsuring the radiation hardness of PbWO4 crystals was one of the main priorities during the construction of the electromagnetic calorimeter of the CMS experiment at CERN. The production on an industrial scale of radiation hard crystals and their certification over a period of several years represented a difficult challenge both for CMS and for the crystal suppliers. The present article reviews the related scientific and technological problems encountered

Nanocrystalline lanthanide-doped Lu3Ga5O12 garnets: interesting materials for light-emitting devices

Nanocrystalline Lu3Ga5O12, with average particle sizes of 40 nm, doped with a wide variety of luminescent trivalent lanthanide ions have been prepared using a sol\u2013gel technique. The structural and morphological properties of the powders have been investigated by x-ray powder diffraction, high resolution transmission electron microscopy and Raman spectroscopy. Structural data have been refined and are presented for Pr3+, Eu3+, Gd3+, Ho3+, Er3+ and Tm3+ dopants, while room temperature excited luminescence spectra and emission decay curves of Eu3+-, Tm3+- and Ho3+-doped Lu3Ga5O12 nanocrystals have been measured and are discussed. The Eu3+ emission spectrum shows typical bands due to 5D0 \u21927FJ (J = 0, 1, 2, 3, 4) transitions and the broadening of these emission bands with the non-exponential behaviour of the decay curves indicates the presence of structural disorder around the lanthanide ions. Lanthanide-doped nanocrystalline Lu3Ga5O12 materials show better luminescence intensities compared to Y2O3, Gd3Ga5O12 and Y3Al5O12 nanocrystalline hosts. Moreover, the upconversion emission intensity in the blue-green region for the Tm3+- and Ho3+-doped samples shows a significant increase upon 647.5 nm excitation with respect to other common oxide hosts doped with the same lanthanide ions

An innovative approach to monitoring the physical stability of constructed fish habitat using drones

In August 2014, a subsurface failure at the Mount Polley mine’s tailings storage facility resulted in a debris flow that scoured Hazeltine Creek and a portion of Edney Creek. Creek rehabilitation planning, design and construction commenced immediately following the incident. A two-phased approach was adopted to reconstruct the creek and restore habitat for fish and riparian wildlife. The first phase was to construct an erosion-resistant engineered channel to control erosion and reduce turbidity in water entering Quesnel Lake. The second phase was to re-establish physical in-stream and riparian habitat along the channel to support a return of biological habitat function. Following the construction of habitat features in sections of Hazeltine Creek and Edney Creek, drone imagery was used to georeference the locations of the constructed habitat. The aerial imagery had sufficient resolution to geospatially document each element of stream habitat, and therefore monitor its physical stability. This novel habitat monitoring technique couples the aerial imagery from drones with geographic information system (GIS) software to reliably determine the stability of each element of habitat and develop a database of those habitat elements. This combination of technologies enables an effective, relatively rapid and low-cost means of monitoring constructed fish habitats.Non UBCUnreviewedOthe

River rehabilitation following a dam breach

A failure in the glaciolacustrine unit underlying the Perimeter Embankment of the Mount Polley Mine Tailings Storage Facility resulted in a breach along a section of the embankment on August 4, 2014. Approximately 9 km of Hazeltine Creek was significantly affected by the resulting debris flow. The initial channel stabilization work was completed quickly and cost-effectively over five months using a combination of traditional channel design techniques and innovative implementation methods, in particular a field-engineered and constructed approach. The channel morphology was developed to mimic pre-existing conditions, including a low-flow channel and two levels of floodplains. Habitat features were designed for the needs of rainbow trout in the portions of the creek that they used; and sockeye and coho salmon in the lower reaches. A field-fit approach was used to maximize flexibility and was consistent with the adaptive approach used in the overall environmental response. A series of design ‘templates’ were developed for each of six morphologically distinct creek reaches, and these templates were applied in the field using a team of professional engineers and biologists and experienced machine crews that implemented those field designs, proving to be highly effective based on the intended outcomes and the rapid timelines under which the construction occurred.Non UBCUnreviewedOthe