119014296
The Photodetector Plane of the 4m Davies Cotton Small Size Telescope for the Cherenkov Telescope Array
Photomultipliers (PMTs) are currently adopted for the photodetector plane of Imaging Atmospheric Cherenkov Telescopes (IACTs). Even though PMT quantum efficiency has improved impressively in the recent years, one of the main limitation for their application in the gamma-astronomy field - the impossibility to operate with moon light - still remains. As a matter of fact, the light excess would lead to significant and faster camera ageing. Solid state detectors, in particular Geiger-mode avalanche photo-diodes (G-APDs) represent a valuable alternative solution to overcome this limitation as demonstrated in the field by the FACT experiment (The First G- APD Cherenkov Telescope). They can be regarded as a more promising long term approach, which can be easily adopted for the new generation of cameras and for the Cherenkov Telescope Array (CTA). We describe here the Photo-Detector Plane (PDP) of the camera for the 4 m Davies Cotton CTA Small Size Telescopes, for which large area G-APD coupled to non-imaging light concentrators are planned. The PDP includes 1296 photosensors, the biasing and pre-amplification stages, the control electronics as well as the mechanical support and the water- tight enclosure. We developed with Hamamatsu a new large area hexagonal shaped G-APD with an area of 93.6 mm^2. This G-APD is divided into 4 channels which will be summed after the pre-amplification stage to maintain an acceptable time characteristic of the signal. The characterization of this device for 50 um and 100 um micro-cell sizes will be discussed and compared to other non-custom photodetectors.
119121537
4 m Davies-Cotton telescope for the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) is the next generation very high energy gamma-ray observatory. It will consist of three classes of telescopes, of large, medium and small sizes. The small telescopes, of 4 m diameter, will be dedicated to the observations of the highest energy gamma-rays, above several TeV. We present the technical characteristics of a single mirror, 4 m diameter, Davies-Cotton telescope for the CTA and the performance of the sub-array consisting of the telescopes of this type. The telescope will be equipped with a fully digital camera based on custom made, hexagonal Geiger-mode avalanche photodiodes. The development of cameras based on such devices is an RnD since traditionally photomultipliers are used. The photodiodes are now being characterized at various institutions of the CTA Consortium. Glass mirrors will be used, although an alternative is being considered: composite mirrors that could be adopted if they meet the project requirements. We present a design of the telescope structure, its components and results of the numerical simulations of the telescope performance.
209976599
Expected discovery potential and sensitivity of the ANTARES neutrino telescope to neutrino point-like sources
3111222
The data acquisition system for the ANTARES neutrino telescope
The ANTARES neutrino telescope is being constructed in the Mediterranean Sea. It consists of a large three-dimensional array of photo-multiplier tubes. The data acquisition system of the detector takes care of the digitisation of the photo-multiplier tube signals, data transport, data filtering, and data storage. The detector is operated using a control program interfaced with all elements. The design and the implementation of the data acquisition system are described.
120269743
Analysis of the Optical Beacon system and search for point-like sources in the ANTARES neutrino telescope
En los ultimos anos estamos siendo testigos de la consolidacion de una nueva disciplina dentro de la astronomia y de la deteccion de rayos cosmicos, la astronomia de neutrinos, Esta tuvo su origen con la deteccion de los primeros neutrinos provenientes de una fuente extra-terrestre, el Sol. Con la deteccion de los neutrinos provenientes de la supernova SN1987A por parte del experimento Kamiokande II, se ampliaron las posibilidades de esta nueva rama de la Fisica de Astroparticulas. Ambos hechos fueron reconocidos por la comunidad cientifica y el ano 2002 el Premio Nobel de Fisica fue otorgado a Raymond Davis y Masatoshi Koshiba por sus estudios pioneros en el campo de la Astrofisica y en particular en la deteccion de neutrinos cosmicos. Esta deteccion de neutrinos solares y de supernovas, se conoce como astronomia de neutrinos de baja energia. Nuevos experimentos, como ANTARES, pretenden extender dicha disciplina de manera que sea posible detectar neutrinos en un mayor rango de energia. Una de las razones fundamentales para querer explorar el Universo usando los neutrinos como mensajeros cosmicos es que este tipo de astronomia ofrece un considerable potencial para el estudio de las regiones mas lejanas o mas densas del Cosmos. La astronomia tradicional basada en fotones ha permitido realizar importantes descubrimientos en todas las longitudes de onda del espectro electromagnetico. Sin embargo, este tipo de astronomia ha encontrado su limitacion en el hecho de que fotones con energias del orden de TeV son absorbidos por el fondo cosmico de radiacion de microondas. Esta incapacidad de poder observar el aspecto mas energetico del Universo ha propiciado que el interes cientifico se dirija hacia nuevos mensajeros cosmicos para explorar las regiones mas densas y lejanas del Universo. De entre ellos, los neutrinos, al ser neutros y solo interactuar debilmente, son los mejores candidatos debido a que no son desviados por los campos
55763273
An exploration of hadronic interactions in blazars using IceCube
Context: Hadronic models, involving matter (proton or nuclei) acceleration in blazar jets, imply high energy photon and neutrino emissions due to interactions of high-energy protons with matter and/or radiation in the source environment. Aims: This paper shows that the sensitivity of the IceCube neutrino telescope in its 40-string configuration (IC-40) is already at the level of constraining the parameter space of purely hadronic scenarios of activity of blazars. Methods: Assuming that the entire source power originates from hadronic interactions, and assuming that the models describe the data, we estimate the expected neutrino flux from blazars based on the observed gamma-ray flux by Fermi, simultaneously with IC-40 observations. We consider two cases separately to keep the number of constrainable parameters at an acceptable level: proton-proton or proton-gamma interactions are dominant. Comparing the IC-40 sensitivity to the neutrino flux expected from some of the brightest blazars, we constrain model parameters characterizing the parent high-energy proton spectrum. Results: We find that when pp interactions dominate, some constraints on the primary proton spectrum can be imposed. For instance, for the tightest constrained source 3C 454.3, the very high energy part of the spectra of blazars is constrained to be harder than E^-2 with cut-off energies in the range of Ecut >10^18 eV. When interactions of high-energy protons on soft photon fields dominate, we can find similarly tight constraints on the proton spectrum parameters. [abridged]
121968204
Non-Classical Traveling Solutions in a Nonlinear Klein Gordon Model
A model with interparticle inharmonic interaction under the Φ4 external potential is studied. Making use of the special relation of relevant parameters, in the continuous limit, it was possible to obtain various non-classical soliton solutions, specifically, compact and peak-like solutions. The solutions undergo a jump on their first derivatives at some points of the space-time manifold. These analytic solutions were obtained by considering strong restrictions on their velocities and on the jump conditions. The energy concentrated in these solutions shows in several cases a discrete spectrum.