: Construction of the first stage of the Pierre Auger Observatory has begun. The aim of the Observatory is to collect unprecedented information about cosmic rays above 10(18) eV. The first phase of the project, the construction and operation of a prototype system, known as the engineering array, has now been completed. It has allowed all of the sub-systems that will be used in the full instrument to be tested under field conditions. In this paper, the properties and performance of these sub-systems are described and their success illustrated with descriptions of some of the events recorded thus far. (C) 2003 Elsevier B.V

The Pierre Auger Observatory is designed to study cosmic rays with energies greater than 10 19 eV. Two sites are envisaged for the observatory, one in each hemisphere,

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The continuum equation of diffusion in hexagonal-close-packed (hcp) metals in the presence of a strain field is deduced. Both the diffusivity and elastodiffusion tensors are microscopically derived from lattice theory for the vacancy and some interstitial configurations. From those expressions the frequently measured activation volume for diffusion is deduced and related to the vacancy dipole tensor at the saddle-point configuration. Also the equation of diffusion towards a hollow cylinder in an homogeneously strained medium is solved. The hollow cylinder models a straight dislocation core in that medium. It is found that the defect-induced lattice distortion, the value and orientation of the external stress field with respect to the cylinder axis (dislocation line), and the orientation of the cylinder axis with respect to the crystal axes affect the strength of that dislocation as a sink for defects.