257 research outputs found
The First Year IceCube-DeepCore Results
The IceCube Neutrino Observatory includes a tightly spaced inner array in the
deepest ice, called DeepCore, which gives access to low-energy neutrinos with a
sizable surrounding cosmic ray muon veto. Designed to be sensitive to neutrinos
at energies as low as 10 GeV, DeepCore will be used to study diverse physics
topics with neutrino signatures, such as dark matter annihilations and
atmospheric neutrino oscillations. The first year of DeepCore physics
data-taking has been completed, and the first observation of atmospheric
neutrino-induced cascades with IceCube and DeepCore are presented.Comment: 4 pages, 3 figures, TAUP 2011 (Journal of Physics: Conference Series
(JCPS)
Results from Seven Years of AMANDA-II
AMANDA is a first-generation high energy neutrino telescope, which has taken
data at the South Pole in its final configuration since 2000. Results from
seven years of operation are presented here, including observation of the
atmopheric neutrino flux and searches for astrophysical neutrinos from cosmic
ray accelerators, gamma ray bursts, and dark matter annihilations. In 2007,
AMANDA was incorporated into the IceCube neutrino telescope, where its higher
density of instrumentation improves the low energy response. In the near
future, AMANDA will be replaced by the IceCube Deep Core, a purpose-built low
energy extension of IceCube.Comment: Presented at Neutrino 2008, Christchurch, New Zealan
Recommended from our members
Limits on a muon flux from Kaluza-Klein dark matter annihilations in the Sun from the IceCube 22-string detector
A search for muon neutrinos from Kaluza-Klein dark matter annihilations in the Sun has been performed with the 22-string configuration of the IceCube neutrino detector using data collected in 104.3 days of live-time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured lightest Kaluza-Klein particle (LKP) WIMPs in the Sun and converted to limits on the LKP-proton cross-sections for LKP masses in the range 250 - 3000 GeV. These results are the most stringent limits to date on LKP annihilation in the Sun
Interplay of energy dependent astrophysical neutrino flavor ratios and new physics effects
We discuss the importance of flavor ratio measurements in neutrino
telescopes, such as by measuring the ratio between muon tracks to cascades, for
the purpose of extracting new physics signals encountered by astrophysical
neutrinos during propagation from the source to the detector. The detected
flavor ratios not only carry the energy information of specific new physics
scenarios which alter the transition probabilities in distinctive ways, but
also the energy dependent flavor composition at the source. In the present
work, we discuss the interplay of these two energy dependent effects and
identify which new physics scenarios can be distinguished from the detected
flavor ratios as a function of astrophysical parameters. We use a recently
developed self-consistent neutrino production model as our toy model to
generate energy dependent source flavor ratios and discuss (invisible) neutrino
decay and quantum decoherence as specific new physics examples. Furthermore, we
identify potentially interesting classes of sources on the Hillas plot for the
purpose of new physics searches. We find that sources with substantial magnetic
fields 10^3 Gauss <= B <= 10^6 Gauss, such as Active Galactic Nuclei (AGN)
cores, white dwarfs, or maybe gamma-ray bursts, have, in principle, the best
discrimination power for the considered new physics scenarios, whereas AGN
jets, which typically perform as pion beam sources, can only discriminate few
sub cases in the new physics effects. The optimal parameter region somewhat
depends on the class of new physics effect considered.Comment: 34 pages, 10 figures, 1 table. Discussion on statistics added, minor
clarifications. Final version published in JCA
High Energy Neutrino Telescopes
This paper presents a review of the history, motivation and current status of
high energy neutrino telescopes. Many years after these detectors were first
conceived, the operation of kilometer-cubed scale detectors is finally on the
horizon at both the South Pole and in the Mediterranean Sea. These new
detectors will perhaps provide us the first view of high energy astrophysical
objects with a new messenger particle and provide us with our first real
glimpse of the distant universe at energies above those accessible by gamma-ray
instruments. Some of the topics that can be addressed by these new instruments
include the origin of cosmic rays, the nature of dark matter, and the
mechanisms at work in high energy astrophysical objects such as gamma-ray
bursts, active galactic nuclei, pulsar wind nebula and supernova remnants.Comment: 33 pages, 21 figures, accepted for publication in the New Journal of
Physic
GZK Photons Above 10 EeV
We calculate the flux of "GZK-photons", namely the flux of photons produced
by extragalactic nucleons through the resonant photoproduction of pions, the so
called GZK effect. This flux depends on the UHECR spectrum on Earth, of the
spectrum of nucleons emitted at the sources, which we characterize by its slope
and maximum energy, on the distribution of sources and on the intervening
cosmological backgrounds, in particular the magnetic field and radio
backgrounds. For the first time we calculate the GZK photons produced by
nuclei. We calculate the possible range of the GZK photon fraction of the total
UHECR flux for the AGASA and the HiRes spectra. We find that for nucleons
produced at the sources it could be as large as a few % and as low as 10^{-4}
above 10 EeV. For nuclei produced at the sources the maximum photon fraction is
a factor of 2 to 3 times smaller above 10 EeV but the minimum could be much
smaller than for nucleons. We also comment on cosmogenic neutrino fluxes.Comment: 20 pages, 9 figures (21 panels), iopart.cls and iopart12.clo needed
to typese
TANAMI blazars in the IceCube PeV-neutrino fields
The IceCube Collaboration has announced the discovery of a neutrino flux in excess of the atmospheric background. Owing to the steeply falling atmospheric background spectrum, events at PeV energies most likely have an extraterrestrial origin. We present the multiwavelength properties of the six radio-brightest blazars that are positionally coincident with these events using contemporaneous data of the TANAMI blazar sample, including high-resolution images and spectral energy distributions. Assuming the X-ray to Îł-ray emission originates in the photoproduction of pions by accelerated protons, the integrated predicted neutrino luminosity of these sources is high enough to explain the two detected PeV events
Calibration and Characterization of the IceCube Photomultiplier Tube
Over 5,000 PMTs are being deployed at the South Pole to compose the IceCube
neutrino observatory. Many are placed deep in the ice to detect Cherenkov light
emitted by the products of high-energy neutrino interactions, and others are
frozen into tanks on the surface to detect particles from atmospheric cosmic
ray showers. IceCube is using the 10-inch diameter R7081-02 made by Hamamatsu
Photonics. This paper describes the laboratory characterization and calibration
of these PMTs before deployment. PMTs were illuminated with pulses ranging from
single photons to saturation level. Parameterizations are given for the single
photoelectron charge spectrum and the saturation behavior. Time resolution,
late pulses and afterpulses are characterized. Because the PMTs are relatively
large, the cathode sensitivity uniformity was measured. The absolute photon
detection efficiency was calibrated using Rayleigh-scattered photons from a
nitrogen laser. Measured characteristics are discussed in the context of their
relevance to IceCube event reconstruction and simulation efforts.Comment: 40 pages, 12 figure
Lateral Distribution of Muons in IceCube Cosmic Ray Events
In cosmic ray air showers, the muon lateral separation from the center of the
shower is a measure of the transverse momentum that the muon parent acquired in
the cosmic ray interaction. IceCube has observed cosmic ray interactions that
produce muons laterally separated by up to 400 m from the shower core, a factor
of 6 larger distance than previous measurements. These muons originate in high
pT (> 2 GeV/c) interactions from the incident cosmic ray, or high-energy
secondary interactions. The separation distribution shows a transition to a
power law at large values, indicating the presence of a hard pT component that
can be described by perturbative quantum chromodynamics. However, the rates and
the zenith angle distributions of these events are not well reproduced with the
cosmic ray models tested here, even those that include charm interactions. This
discrepancy may be explained by a larger fraction of kaons and charmed
particles than is currently incorporated in the simulations
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