119252420
Neutrino searches with the IceCube telescope
Abstract The IceCube Neutrino Observatory is an array of 5,160 photomultipliers (PMTs) deployed on 86 strings at 1.5-2.5 km depth within the ice at the South Pole. The main goal of the IceCube experiment is the detection of an astrophysical neutrino signal. In this contribution we present the results of the point source analysis on the data taken from April 2008 to May 2011, when three detector configurations were operated: the 40-string configuration (IC-40), the 59-string configuration (IC-59) and the 79-string configuration (IC-79). No significant excess indicative of point sources of neutrinos has been found, and we present upper limits for an E − 2 muon neutrino flux for a list of candidate sources. For the first time these limits start to reach 10 − 12 TeV − 1 cm − 2 s − 1 in some parts of the sky.
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.
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.
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
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.
209976599
Expected discovery potential and sensitivity of the ANTARES neutrino telescope to neutrino point-like sources
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.