Bøger af Malek Abunaemeh

Photometry and astrometry performed with charge coupled devices (CCDs) at the focal planes of large telescopes are indispensable tools of modern observational cosmology, astrophysics and astronomy. In the modern era of precision cosmology, variations in the sub-pixel sensitivity and spectral response of CCDs can affect the science yield of observations and must be characterized. Unfortunately, there have been very few studies to measure the sub-pixel response variations of CCDs, particularly in the context of observational cosmology. It is the aim of this study is to perform the first measurement of the photometric and astrometric fidelity of high-resistivity, p-channel CCDs. These devices have been selected for major upcoming observational cosmology missions such as the space-based Supernova Acceleration Probe satellite (SNAP) and the ground-based Dark Energy Survey. An experimental study has been performed to make detailed measurements of the intrapixel response variations of these devices at a precision exceeding 2%, which is the level of precision required for the missions.

Tristructural isotropic fuel particles were originally developed in Germany for high-temp gas cooled reactors and it is considered as the fuel design of choice for the next generation of nuclear reactors. Its design consists of a fuel kernel of UOx coated with several layers having different functions. One of these functions is a containments shell/diffusion barrier for the fission fragments, pyrolytic carbon. This material does not offer a perfect barrier, due to its inherent crystalline structure, which is like graphite and therefore, impossible to mold in one continuous sheet around the spherical fuel bead. Plane boundaries allow fragment diffusion at a much higher rate than through the plane. In this study we investigate the possibility of replacing pyrolytic carbon with GPC. We studied the evolution of their physical properties and structure as a function of the radiation environment in which they were exposed. The temperature that the samples were held during irradiation was similar to those in the core of the Generation IV nuclear reactor (~1000°C). A procedure for manufacturing GPC along with explorations of the chemical sand physical analysis before and after Irradiation.