717 research outputs found
Cherenkov Flashes and Fluorescence Flares on Telescopes: New lights on UHECR Spectroscopy while unveiling Neutrinos Astronomy
Cherenkov Telescopes (as Magic, Hess and Veritas), while pointing
horizontally should reveal also the fluorescence flare tails of nearby
down-going air-showers. Such air-showers, born at higher (tens km) altitudes,
are growing and extending up to lowest atmospheres (EeVs) or up to higher (few
km) quotas (PeVs). Viceversa, as it has been foreseen and only recently
observed, the opposite takes place. Fluorescence Telescopes made for UHECR
detection may be blazed by inclined Cherenkov lights. The geomagnetic splitting
may tag the energy as well as the inclined shower footprint as seen in a recent
peculiar event in AUGER. Additional stereoscopic detection may define the event
origination distance and its consequent primary composition, extending our
understanding on UHECR composition, while unveling a novel tau Neutrino
Astronomy.Comment: 5 pages, 5 figures, Preprint submitted to Nuclear Instruments and
Methods A. Only editorial format chang
Potential of a Neutrino Detector in the ANDES Underground Laboratory for Geophysics and Astrophysics of Neutrinos
The construction of the Agua Negra tunnels that will link Argentina and Chile
under the Andes, the world longest mountain range, opens the possibility to
build the first deep underground labo- ratory in the Southern Hemisphere. This
laboratory has the acronym ANDES (Agua Negra Deep Experiment Site) and its
overburden could be as large as \sim 1.7 km of rock, or 4500 mwe, providing an
excellent low background environment to study physics of rare events like the
ones induced by neutrinos and/or dark matter. In this paper we investigate the
physics potential of a few kiloton size liquid scintillator detector, which
could be constructed in the ANDES laboratory as one of its possible scientific
programs. In particular, we evaluate the impact of such a detector for the
studies of geoneutrinos and galactic supernova neutrinos assuming a fiducial
volume of 3 kilotons as a reference size. We emphasize the complementary roles
of such a detector to the ones in the Northern Hemisphere neutrino facilities
through some advantages due to its geographical location.Comment: 20 pages, 16 figures and 9 table
Photon-axion mixing and ultra-high-energy cosmic rays from BL Lac type objects -- Shining light through the Universe
Photons may convert into axion like particles and back in the magnetic field
of various astrophysical objects, including active galaxies, clusters of
galaxies, intergalactic space and the Milky Way. This is a potential
explanation for the candidate neutral ultra-high-energy (E>10^18 eV) particles
from distant BL Lac type objects which have been observed by the High
Resolution Fly's Eye experiment. Axions of the same mass and coupling may
explain also TeV photons detected from distant blazars.Comment: Revtex 10 pages, 6 figures. V.2: QED dispersion effects taken into
account; principal results unchanged. V3: misprints and sqrt(4*pi) factors in
Gauss to eV conversion corrected; conclusions unchange
Neutrino initiated cascades at mid and high altitudes in the atmosphere
High energy neutrinos play a very important role for the understanding of the
origin and propagation of ultra high energy cosmic rays (UHECR). They can be
produced as a consequence of the hadronic interactions suffered by the cosmic
rays in the acceleration regions, as by products of the propagation of the
UHECR in the radiation background and as a main product of the decay of super
heavy relic particles. A new era of very large exposure space observatories, of
which the JEM-EUSO mission is a prime example, is on the horizon which opens
the possibility of neutrino detection in the highest energy region of the
spectrum. In the present work we use a combination of the PYTHIA interaction
code with the CONEX shower simulation package in order to produce fast
one-dimensional simulations of neutrino initiated showers in air. We make a
detail study of the structure of the corresponding longitudinal profiles, but
focus our physical analysis mainly on the development of showers at mid and
high altitudes, where they can be an interesting target for space fluorescence
observatories.Comment: To appear in Astroparticle Physic
Detecting gamma-ray bursts with the Pierre Auger Observatory using the single particle technique
During the past ten years, gamma-ray bursts (GRB) have been extensively
studied in the keV-MeV energy range but the high energy emission still remain
mysterious. Ground based observatories have the possibility to investigate
energy range around one GeV using the "single particle technique". The aim of
the present study is to investigate the capability of the Pierre Auger
Observatory to detect the high energy emission of GRBs with such a technique.
According to the detector response to photon showers around one GeV, and making
reasonable assumptions about the high energy emission of GRBs, we show that the
Pierre Auger Observatory is a competitive instrument for this technique, and
that water tanks are very promising detectors for the single particle
technique.Comment: 4 pages, 2 figures, to appear in the 29th ICRC conference (Pune,
India) proceeding
Sites for Gamma-ray Astronomy in Argentina
We have searched for possible sites in Argentina for the installation of
large air Cherenkov telescope arrays and water Cherenkov systems. At present
seven candidates are identified at altitudes from 2500 to 4500 m. The highest
sites are located at the Northwest of the country, in La Puna. Sites at 2500
and 3100 m are located in the West at El Leoncito Observatory, with excellent
infrastructure. A description of these candidate sites is presented with
emphasis on infrastructure and climatology.Comment: Submitted to Proceedings of "4th Heidelberg International Symposium
on High Energy Gamma-Ray Astronomy 2008
Flux of atmospheric muons: Comparison between AIRES simulations and CAPRICE98 data
We report on a comparison between the flux of muons in the atmosphere
measured by the CAPRICE98 experiment and simulations performed with the air
shower simulation program AIRES. To reduce systematic uncertainties we have
used as input the primary fluxes of protons and helium nuclei also measured by
the CAPRICE98 experiment. Heavy nuclei are also taken into account in the
primary flux, and their contribution to the muon flux is discussed. The results
of the simulations show a very good agreement with the experimental data, at
all altitudes and for all muon momenta. With the exception of a few isolated
points, the relative differences between measured data and simulations are
smaller than 20 %; and in all cases compatible with zero within two standard
deviations. The influence of the input cosmic ray flux on the results of the
simulations is also discussed. This report includes also an extensive analysis
of the characteristics of the simulated fluxes.Comment: Accepted for publication in Physical Review
ISOGAL-DENIS detection of red giants with weak mass loss in the Galactic Bulge
The ISOGAL project is a survey of the stellar populations, structure, and
recent star formation history of the inner disk and bulge of the Galaxy. ISOGAL
combines 15 and 7micron ISOCAM observations with DENIS IJKs data to determine
the nature of a source and the interstellar extinction. In this paper we report
an ISOGAL study of a small field in the inner Galactic Bulge (l=0deg, b=1.0deg,
area=0.035 sq. deg) as a prototype of the larger area ISOGAL survey of the
inner Galaxy. The five wavelengths of ISOGAL+DENIS, together with the
relatively low and constant extinction in front of this specific field, allow
reliable determination of the nature of the sources. The primary scientific
result of this paper is evidence that the most numerous class of ISOGAL
15micron sources are Red Giants in the Galactic bulge and central disk, with
luminosities just above or close to the RGB tip and weak mass-loss rates. They
form loose sequences in the magnitude-colour diagrams [15]/Ks-[15] and
[15]/[7]-[15]. Their large excesses at 15micron with respect to 2micron and
7micron is due to circumstellar dust produced by mass-loss at low rates. These
ISOGAL results are the first systematic evidence and study of dust emission at
this early stage (''Intermediate'' AGB), before the onset of the large
mass-loss phase. It is thus well established that efficient dust formation is
already associated with such low mass-loss rates during this early phase.Comment: 15 pages, 9 figures, accepted for publication in Astronomy and
Astrophysics Journa
Results of the engineering run of the coherent neutrino nucleus interaction experiment (CONNIE)
The CONNIE detector prototype is operating at a distance of 30 m from the core of a 3.8 GWth nuclear reactor with the goal of establishing Charge-Coupled Devices (CCD) as a new technology for the detection of coherent elastic neutrino-nucleus scattering. We report on the results of the engineering run with an active mass of 4 g of silicon. The CCD array is described, and the performance observed during the first year is discussed. A compact passive shield was deployed around the detector, producing an order of magnitude reduction in the background rate. The remaining background observed during the run was stable, and dominated by internal contamination in the detector packaging materials. The in-situ calibration of the detector using X-ray lines from fluorescence demonstrates good stability of the readout system. The event rates with the reactor ON and OFF are compared, and no excess is observed coming from nuclear fission at the power plant. The upper limit for the neutrino event rate is set two orders of magnitude above the expectations for the standard model. The results demonstrate the cryogenic CCD-based detector can be remotely operated at the reactor site with stable noise below2 e RMS and stable background rates. The success of the engineering test provides a clear path for the upgraded 100 g detector to be deployed during 2016.Fil: Aguilar Arevalo, A.. Universidad Nacional Autónoma de México; MéxicoFil: Bertou, Xavier Pierre Louis. Comisión Nacional de EnergÃa Atómica; Argentina. Comisión Nacional de EnergÃa Atómica. Fundación José A. Balseiro; ArgentinaFil: Bonifazi, C.. Universidade Federal do Rio de Janeiro; BrasilFil: Butner, M.. Fermi National Accelerator Laboratory; Estados UnidosFil: Cancelo, G.. Fermi National Accelerator Laboratory; Estados UnidosFil: Castañeda Vazquez, A.. Universidad Nacional Autónoma de México; MéxicoFil: Cervantes Vergara, B.. Universidad Nacional Autónoma de México; MéxicoFil: Chavez, C. R.. Universidad Nacional de Asunción; ParaguayFil: Da Motta, H.. Centro Brasileiro de Pesquisas FÃsicas; BrasilFil: D'Olivo, J. C.. Universidad Nacional Autónoma de México; MéxicoFil: Dos Anjos, J.. Centro Brasileiro de Pesquisas FÃsicas; BrasilFil: Estrada, J.. Fermi National Accelerator Laboratory; Estados UnidosFil: Fernández Moroni, Guillermo. Universidad Nacional del Sur. Departamento de IngenierÃa Eléctrica y de Computadoras. Instituto ; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Ford, R.. Fermi National Accelerator Laboratory; Estados UnidosFil: Foguel, A.. Centro Brasileiro de Pesquisas FÃsicas; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Hernandez Torres, K. P.. Universidad Nacional Autónoma de México; MéxicoFil: Izraelevitch, F.. Fermi National Accelerator Laboratory; Estados UnidosFil: Kavner, A.. University of Michigan; Estados UnidosFil: Kilminster, B.. Universitat Zurich; SuizaFil: Kuk, K.. Fermi National Accelerator Laboratory; Estados UnidosFil: Lima Jr, H. P.. Centro Brasileiro de Pesquisas FÃsicas; BrasilFil: Makler, M.. Centro Brasileiro de Pesquisas FÃsicas; BrasilFil: Molina, J.. Universidad Nacional de Asunción; ParaguayFil: Moreno Granados, G.. Universidad Nacional Autónoma de México; MéxicoFil: Moro, Juan Manuel. Universidad Nacional del Sur. Departamento de IngenierÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Paolini, Eduardo Emilio. Universidad Nacional del Sur. Departamento de IngenierÃa Eléctrica y de Computadoras. Instituto ; ArgentinaFil: Sofo Haro, Miguel Francisco. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Trillaud, F.. Universidad Nacional Autónoma de México; MéxicoFil: Wagner, S.. Centro Brasileiro de Pesquisas FÃsicas; Brasil. Pontificia Universidade Católica do Rio Grande do Sul; Brasi
Observing muon decays in water Cherenkov detectors at the Pierre Auger Observatory
Muons decaying in the water volume of a Cherenkov detector of the Pierre
Auger Observatory provide a useful calibration point at low energy. Using the
digitized waveform continuously recorded by the electronics of each tank, we
have devised a simple method to extract the charge spectrum of the Michel
electrons, whose typical signal is about 1/8 of a crossing vertical muon. This
procedure, moreover, allows continuous monitoring of the detector operation and
of its water level. We have checked the procedure with high statistics on a
test tank at the Observatory base and applied with success on the whole array.Comment: 4 pages, 2 figures, proceedings of the 29th ICRC Pune, Indi
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