909 research outputs found
Recent results from the Pierre Auger Observatory
Since June 2008 the Pierre Auger Observatory has been taking data in its final configuration. Since then two main upgrades have been completed: the High Elevation Angle Telescopes (HEAT) and an infill in the surface region covered by HEAT, with the main goal of bringing the energy threshold down to 1017 eV. In this paper, I will give an overview of the main recent results of the Auger Observatory. More specifically, I will discuss the all-particle energy spectrum and the evidence for the GZK features, the measurement of the elongation rate and the
evidence for anisotropy in the subset of the highest energy events. Systematic uncertainties will be discussed
Multiscale autocorrelation function: a new approach to anisotropy studies
We present a novel catalog-independent method, based on a scale dependent
approach, to detect anisotropy signatures in the arrival direction distribution
of the ultra highest energy cosmic rays (UHECR). The method provides a good
discrimination power for both large and small data sets, even in presence of
strong contaminating isotropic background. We present some applications to
simulated data sets of events corresponding to plausible scenarios for charged
particles detected by world-wide surface detector-based observatories, in the
last decades.Comment: 18 pages, 9 figure
A new multiparametric topological method for determining the primary cosmic ray mass composition in the knee energy region
The determination of the primary cosmic ray mass composition from the
characteristics of extensive air showers (EAS), obtained at an observation
level in the lower half of the atmosphere, is still an open problem. In this
work we propose a new method of the Multiparametric Topological Analysis and
show its applicability for the determination of the mass composition of the
primary cosmic rays at the PeV energy region.Comment: 8 pages, 4 figures, talk given at Vulcano 2004 Workshop 'Frontier
Objects in Physics and Astrophysics', Vulcano, Italy, 24-29.05.04, to be
published in the Proceedings of the Worksho
Self-energy Effects in the Superfluidity of Neutron Matter
The superfluidity of neutron matter in the channel is studied by
taking into account the effect of the ground-state correlations in the
self-energy. To this purpose the gap equation has been solved within the
generalized Gorkov approach. A sizeable suppression of the energy gap is driven
by the quasi-particle strength around the Fermi surface.Comment: 8 pages and 3 figure
A new method for the UHECR mass composition studies
The detemination of the primary cosmic ray mass composition from the
longitudinal development of atmospheric cascades is still an open problem. In
this work we propose a new method of the multiparametric topological analysis
and show that if both X - the depth of shower maximum and N -
the number of charged particles in the shower maximum are used, reliable
results can be obtained.Comment: 6 pages, 4 figures, talk given at CRIS2004 Cosmic Ray International
Seminar 'GZK and Surroundings', 31.05-4.06.04, Catania, Italy, to be
published in Nucl.Phys.B (Proc.Suppl.
Bathymetric Mapping and Sonar Imaging of Tufa at Green Lakes: Fayetteville, New York
The Fayetteville Green Lakes State Park, located in Fayetteville, New York, consists of two deep (48 m+), meromictic (non-mixing) lakes with unique limnological, bacterial, and chemical characteristics. These lakes, named Round Lake and its larger companion Green Lake, have been extensively studied for nearly 200 years because of their unique character. The lake water contains two distinct layers, the oxygen-rich mixolimnion and the anoxic monimolimnion divided by the chemocline (a chemical compositional boundary). Tufa deposits exist along the shorelines of both lakes at various depths and are a product of groundwater output into the lakes, as well as the lakes’ unique water chemistry and microbial communities. Here, we use sonar imaging techniques to produce updated bathymetric maps of Green and Round Lake, and provide the first detailed characterization of the near-shore environment using side-scanning sonar imagery to determine the locations and morphologies of tufa deposits. We also document shoreline debris specifically large tree trunks and branches which have fallen into the lake over time and are frequently encrusted. We identified fourteen locations of tufa ranging from large formations (10s of meters long) to small tufa heads (~1 m) in Green Lake. Our updated bathymetry and documentation of tufa locations and geometry expand on an extensive history of prior work, will aid future investigators by revealing lesser-known tufa localities, and will assist the Fayetteville Green Lakes State Park with monitoring and conservation efforts for this ecologically unique area
Comparison between methods for the determination of the primary cosmic ray mass composition from the longitudinal profile of atmospheric cascades
The determination of the primary cosmic ray mass composition from the
longitudinal development of atmospheric cascades is still a debated issue. In
this work we discuss several data analysis methods and show that if the entire
information contained in the longitudinal profile is exploited, reliable
results may be obtained. Among the proposed methods FCC ('Fit of the Cascade
Curve'), MTA ('Multiparametric Topological Analysis') and NNA ('Neural Net
Analysis') with conjugate gradient optimization algorithm give the best
accuracy.Comment: 22 pages, 11 figures, accepted by Astroparticle Physics, minor
misprints and an extra figure remove
Earth-skimming UHE Tau Neutrinos at the Fluorescence Detector of Pierre Auger Observatory
Ultra high energy neutrinos are produced by the interaction of hadronic
cosmic rays with the cosmic radiation background. More exotic scenarios like
topological defects or new hadrons predict even larger fluxes. In particular,
Earth-skimming tau neutrinos could be detected by the Fluorescence Detector
(FD) of Pierre Auger Observatory. A detailed evaluation of the expected number
of events has been performed for a wide class of neutrino flux models. An
updated computation of the neutrino-nucleon cross section and of the tau energy
losses has been carried out. For the most optimistic theoretical models, about
one Earth-skimming neutrino event is expected in several years at FD.Comment: 26 pages, 13 figures, version accepted for publication on
Astroparticle Physic
Optical Relative Calibration and Stability Monitoring for the Auger Fluorescence Detector
The stability of the fluorescence telescopes of the Pierre Auger Observatory
is monitored with the optical relative calibration setup. Optical fibers
distribute light pulses to three different diffuser groups within the optical
system. The total charge per pulse is measured for each pixel and compared with
reference calibration measurements. This allows monitoring the short and long
term stability with respect of the relative timing between pixels and the
relative gain for each pixel. The designs of the LED calibration unit (LCU) and
of the Xenon flash lamp used for relative calibration, are described and their
capabilities to monitor the stability of the telescope performances are
studied. We report the analysis of relative calibration data recorded during
2004. Fluctuations in the relative calibration constants provide a measure of
the stability of the FD.Comment: 4 pp. To appear in the proceedings of 29th International Cosmic Ray
Conference (ICRC 2005), Pune, India, 3-11 Aug 200
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