The Drift Chambers Of The Nomad Experiment

We present a detailed description of the drift chambers used as an active target and a tracking device in the NOMAD experiment at CERN. The main characteristics of these chambers are a large area, a self supporting structure made of light composite materials and a low cost. A spatial resolution of 150 microns has been achieved with a single hit efficiency of 97%.Comment: 42 pages, 26 figure

Le suivi à long terme du CO2 atmosphérique

International audienceL'étude du climat, enjeu majeur Pour reconstruire l'évolution du climat d'une période donnée et replacer les événements dans un cadre chronologique global, l'exploitation des archives climatiques impose de jongler entre des méthodes de datation très variées. La mesure de la radioactivité par différentes techniques y joue souvent un rôle central

Development of a transparent optical telescope for absolute positioning with respect to a reference laser beam [for ATLAS muon chambers]

We have developed an optical system which permits the absolute positioning of an element with respect to a reference laser beam. The resolution is of the order of 10 mu m in translation and 50 mu rad in rotation. It is highly transparent (>90%) permitting several elements to be aligned. A calibration procedure has also been studied in order to be independent of internal deformations. (4 refs)

Experimental study of the nucleation and growth of c-component loops under charged particle irradiations of recrystallized Zircaloy-4

Recrystallized zirconium alloys, used as structural materials for the Pressurized Water Reactor fuel assembly, undergo under neutron irradiation induced stress free growth which accelerates for high irradiation doses. This acceleration is correlated with the formation of c-component vacancy dislocation loops in the basal plane. Since these defects are responsible for breakaway growth of recrystallized zirconium alloys, it is of prime importance to know the various factors that can affect their nucleation and growth. In the present work, two types of charged particle irradiations were conducted on recrystallized Zircaloy-4 samples in order to study c-component loops. A 2 MeV proton irradiation was performed up to a dose of 11.5 dpa at 623 K, and 600 key Zr ion irradiations were carried out at 573 K up to 7 dpa. For the first time after those charged particle irradiations, c-component loops were observed by Transmission Electron Microscopy. It has been shown that under Zr ion irradiation they start to nucleate and grow beyond a threshold dose as for neutron irradiation. The differences in the c-component loop microstructure are discussed for both ion irradiations and compared to the microstructure observed after neutron irradiation. Furthermore, it is shown that after proton irradiation the irradiated layer exhibits a misfit strain which is consistent with the irradiation induced growth of recrystallized zirconium alloys. (c) 2011 Elsevier B.V. All rights reserved