Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.

The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project. ?? 2013 Elsevier B.V. All rights reserved

he Pierre Auger Observatory, located on a vast, high plain in western\ud Argentina, is the world's largest cosmic ray observatory. The objectives\ud of the Observatory are to probe the origin and characteristics of cosmic\ud rays above 10(17) eV and to study the interactions of these, the most\ud energetic particles observed in nature. The Auger design features an\ud array of 1660 water Cherenkov particle detector stations spread over\ud 3000 km(2) overlooked by 24 air fluorescence telescopes. In addition,\ud three high elevation fluorescence telescopes overlook a 23.5 km(2),\ud 61-detector infilled array with 750 in spacing. The Observatory has been\ud in successful operation since completion in 2008 and has recorded data\ud from an exposure exceeding 40,000 km(2) sr yr. This paper describes the\ud design and performance of the detectors, related subsystems and\ud infrastructure that make up the Observatory

Yves was one of the driving forces during the design and construction of the Silicon Tracker. He was killed in an avalanche on the Pointe Percee in January 1996, a victim of his passion for the high mountains. We would like to dedicate this paper to his memory. AbstractThe DELPHI Silicon Tracker, an ensemble of microstrips, ministrips and pixels, was completed in 1997 and has accumulated over 70 pb 1 of high energy data. The Tracker is optimised for the LEP2 physics programme. It consists of a silicon microstrip barrel and endcaps with layers of silicon pixel and ministrip detectors. In the barrel part, three dimensional b tagging information is available down to a polar angle of 25 . Impact parameter resolutions have been measured of 28 m 71= (p sin 3 2 ) m i n R and 34 m 69=p m i n Rz, where p is the track momentum in GeV=c. The amount of material has been kept low with the use of double-sided detectors, double-metal readout, and light mechanics. The pixels have dimensions of 330 330 m 2 and the ministrips have a readout pitch of 200 m. The forward part of the detector shows average e ciencies of more than 96%, has signal-to-noise ratios of up to 40 in the ministrips, and noise levels at the level of less than one part per million in the pixels. Measurements of space points with low backgrounds are provided, leading to a vastly improved tracking e ciency for the region with polar angle less than 25 .3