Composite mirror facets for ground based gamma ray astronomy

Composite mirrors for gamma-ray astronomy have been developed to fulfill the specifications required for the next generation of Cherenkov telescopes represented by CTA (Cherenkov Telescope Array). In addition to the basic requirements on focus and reflection efficiency, the mirrors have to be stiff, lightweight, durable and cost efficient. In this paper, the technology developed to produce such mirrors is described, as well as some tests that have been performed to validate them. It is shown that these mirrors comply with the needs of CTA, making them good candidates for use on a significant part of the array.Comment: 16 pages, 13 figures, accepted to be published on NIM

Mirror development for the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is a planned observatory for very-high energy gamma-ray astronomy. It will consist of several tens of telescopes of different sizes, with a total mirror area of up to 10,000 square meters. Most mirrors of current installations are either polished glass mirrors or diamond-turned aluminium mirrors, both labour intensive technologies. For CTA, several new technologies for a fast and cost-efficient production of light-weight and reliable mirror substrates have been developed and industrial pre-production has started for most of them. In addition, new or improved aluminium-based and dielectric surface coatings have been developed to increase the reflectance over the lifetime of the mirrors compared to those of current Cherenkov telescope instruments.Fil: Forster, A.. Max-Planck-Institut fur Kernphysik; AlemaniaFil: Armstrong, T.. Durham University; Reino UnidoFil: Baba, H.. Ibaraki University; JapónFil: Bähr, J.. No especifíca;Fil: Bonardi, A.. Universitat Tübingen; AlemaniaFil: Bonnoli, G.. Osservatorio Astronomico di Brera; ItaliaFil: Brun, P.. No especifíca;Fil: Canestrari, R.. Osservatorio Astronomico di Brera; ItaliaFil: Chadwick, P.. Durham University; Reino UnidoFil: Chikawa, M.. University of Tokyo; JapónFil: Carton, P.-H.. Centre de Saclay; FranciaFil: De Souza, V.. Universidade de Sao Paulo; BrasilFil: Dipold, J.. Universidade de Sao Paulo; BrasilFil: Doro, M.. Università di Padova; ItaliaFil: Durand, D.. No especifíca;Fil: Dyrda, M.. Polish Academy of Sciences; ArgentinaFil: Giro, E.. Osservatorio Astronomico di Padova; ItaliaFil: Glicenstein, J.-F.. No especifíca;Fil: Hanabata, Y.. Kinki University; JapónFil: Hayashida, M.. University of Tokyo; JapónFil: Hrabovski, M.. No especifíca;Fil: Jeanney, C.. Centre de Saclay; FranciaFil: Kagaya, M.. Ibaraki University; JapónFil: Katagiri, H.. Ibaraki University; JapónFil: Lessio, L.. Osservatorio Astronomico di Padova; ItaliaFil: Mandat, D.. Institute of Physics of the Academy of Sciences of the Czech Republic; República ChecaFil: Mariotti, M.. Università di Padova; ItaliaFil: Medina, Maria Clementina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Yoshida, T.. Ibaraki University; Japón33rd International Cosmic Ray ConferenceRío de JaneiroBrasilBrazilian Physical Societ

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

OH kinetics in photo-triggered discharges used for VOCs conversion

The kinetic of the hydroxyl radical is studied in N2/O2/H2O mixtures with small amounts of acetone or isopropyl alcohol (0.5%). The radical density is measured in absolute value in the afterglow of a photo-triggered discharge, which generates an homogeneous transient non-equilibrium plasma, using a time resolved absorption measurement method. For dry mixtures, experimental results are compared to predictions of a self-consistent 0D discharge and kinetic model. It is shown that dissociation of the VOCs through quenching collisions of nitrogen metastable states plays an important role in the production of OH. Measurements can not be explained looking only at the oxidation of acetone or IPA by the oxygen atom. This result is reinforced by experimental results about the OH density in wet mixtures, with or without VOCs, compared to dry ones

A Highly Efficient, Angle-Insensitive Solar Quantum Concentrator Based on Microstructured Plastic Optical Fiber

International audienceA new device made of very specific microstructured fluorescent plastic optical fibers, capable of concentrating solar radiation towards photovoltaic solar cells is studied in the QUYOS project. This device transforms a multidirectionnal and polychromatic flux of solar light to a monochromatic and monodirectionnal intense flux of light with a high conversion efficiency. The very specific behaviour of these fibers is due to the convergence of several quantum phenomena. Mainly the coincidence of the fluorescent band of the dye with the forbidden band of the photonic crystal from the microstructured fiber restricts the phase space of desexcitation only along the axis of the fiber. Moreover, a coupling of the fluorescence with the allowed modes of the central waveguide of the fiber does enhance the radiative desexcitation thanks to the Purcell effect