782 research outputs found
The Composition of Cosmic Rays at the Knee
The observation of a small change in spectral slope, or 'knee' in the fluxes
of cosmic rays near energies 10^15 eV has caused much speculation since its
discovery over 40 years ago. The origin of this feature remains unknown. A
small workshop to review some modern experimental measurements of this region
was held at the Adler Planetarium in Chicago, USA in June 2000. This paper
summarizes the results presented at this workshop and the discussion of their
interpretation in the context of hadronic models of atmospheric airshowers.Comment: 36 pages, 10 figure
The AMANDA Neutrino Telescope: Principle of Operation and First Results
AMANDA is a high-energy neutrino telescope presently under construction at
the geographical South Pole. In the Antarctic summer 1995/96, an array of 80
optical modules (OMs) arranged on 4 strings (AMANDA-B4) was deployed at depths
between 1.5 and 2 km. In this paper we describe the design and performance of
the AMANDA-B4 prototype, based on data collected between February and November
1996. Monte Carlo simulations of the detector response to down-going
atmospheric muon tracks show that the global behavior of the detector is
understood. We describe the data analysis method and present first results on
atmospheric muon reconstruction and separation of neutrino candidates. The
AMANDA array was upgraded with 216 OMs on 6 new strings in 1996/97
(AMANDA-B10), and 122 additional OMs on 3 strings in 1997/98.Comment: 36 pages, 23 figures, submitted to Astroparticle Physic
Balloon observations of galactic cosmic ray helium before and during a Forbush decrease
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95497/1/grl6996.pd
Search for Point Sources of High Energy Neutrinos with AMANDA
This paper describes the search for astronomical sources of high-energy
neutrinos using the AMANDA-B10 detector, an array of 302 photomultiplier tubes,
used for the detection of Cherenkov light from upward traveling
neutrino-induced muons, buried deep in ice at the South Pole. The absolute
pointing accuracy and angular resolution were studied by using coincident
events between the AMANDA detector and two independent telescopes on the
surface, the GASP air Cherenkov telescope and the SPASE extensive air shower
array. Using data collected from April to October of 1997 (130.1 days of
livetime), a general survey of the northern hemisphere revealed no
statistically significant excess of events from any direction. The sensitivity
for a flux of muon neutrinos is based on the effective detection area for
through-going muons. Averaged over the Northern sky, the effective detection
area exceeds 10,000 m^2 for E_{mu} ~ 10 TeV. Neutrinos generated in the
atmosphere by cosmic ray interactions were used to verify the predicted
performance of the detector. For a source with a differential energy spectrum
proportional to E_{nu}^{-2} and declination larger than +40 degrees, we obtain
E^2(dN_{nu}/dE) <= 10^{-6}GeVcm^{-2}s^{-1} for an energy threshold of 10 GeV.Comment: 46 pages, 22 figures, 4 tables, submitted to Ap.
Limits to the muon flux from WIMP annihilation in the center of the Earth with the AMANDA detector
A search for nearly vertical up-going muon-neutrinos from neutralino
annihilations in the center of the Earth has been performed with the AMANDA-B10
neutrino detector. The data sample collected in 130.1 days of live-time in
1997, ~10^9 events, has been analyzed for this search. No excess over the
expected atmospheric neutrino background is oberved. An upper limit at 90%
confidence level on the annihilation rate of neutralinos in the center of the
Earth is obtained as a function of the neutralino mass in the range 100
GeV-5000 GeV, as well as the corresponding muon flux limit.Comment: 14 pages, 11 figures. Version accepted for publication in Physical
Review
Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector
Data from the AMANDA-B10 detector taken during the austral winter of 1997
have been searched for a diffuse flux of high energy extraterrestrial
muon-neutrinos, as predicted from, e.g., the sum of all active galaxies in the
universe. This search yielded no excess events above those expected from the
background atmospheric neutrinos, leading to upper limits on the
extraterrestrial neutrino flux. For an assumed E^-2 spectrum, a 90% classical
confidence level upper limit has been placed at a level E^2 Phi(E) = 8.4 x
10^-7 GeV cm^-2 s^-1 sr^-1 (for a predominant neutrino energy range 6-1000 TeV)
which is the most restrictive bound placed by any neutrino detector. When
specific predicted spectral forms are considered, it is found that some are
excluded.Comment: Submitted to Physical Review Letter
An All-Sky Search for Three Flavors of Neutrinos from Gamma-Ray Bursts with the IceCube Neutrino Observatory
We present the results and methodology of a search for neutrinos produced in
the decay of charged pions created in interactions between protons and
gamma-rays during the prompt emission of 807 gamma-ray bursts (GRBs) over the
entire sky. This three-year search is the first in IceCube for shower-like
Cherenkov light patterns from electron, muon, and tau neutrinos correlated with
GRBs. We detect five low-significance events correlated with five GRBs. These
events are consistent with the background expectation from atmospheric muons
and neutrinos. The results of this search in combination with those of
IceCube's four years of searches for track-like Cherenkov light patterns from
muon neutrinos correlated with Northern-Hemisphere GRBs produce limits that
tightly constrain current models of neutrino and ultra high energy cosmic ray
production in GRB fireballs.Comment: 33 pages, 14 figures; minor changes made to match published version
in the Astrophysical Journal, 2016 June 2
Improved limits on dark matter annihilation in the Sun with the 79-string IceCube detector and implications for supersymmetry
We present an improved event-level likelihood formalism for including
neutrino telescope data in global fits to new physics. We derive limits on
spin-dependent dark matter-proton scattering by employing the new formalism in
a re-analysis of data from the 79-string IceCube search for dark matter
annihilation in the Sun, including explicit energy information for each event.
The new analysis excludes a number of models in the weak-scale minimal
supersymmetric standard model (MSSM) for the first time. This work is
accompanied by the public release of the 79-string IceCube data, as well as an
associated computer code for applying the new likelihood to arbitrary dark
matter models.Comment: 24 pages, 8 figs, 1 table. Contact authors: Pat Scott & Matthias
Danninger. Likelihood tool available at http://nulike.hepforge.org. v2: small
updates to address JCAP referee repor
All-sky search for time-integrated neutrino emission from astrophysical sources with 7 years of IceCube data
Since the recent detection of an astrophysical flux of high energy neutrinos,
the question of its origin has not yet fully been answered. Much of what is
known about this flux comes from a small event sample of high neutrino purity,
good energy resolution, but large angular uncertainties. In searches for
point-like sources, on the other hand, the best performance is given by using
large statistics and good angular reconstructions. Track-like muon events
produced in neutrino interactions satisfy these requirements. We present here
the results of searches for point-like sources with neutrinos using data
acquired by the IceCube detector over seven years from 2008--2015. The
discovery potential of the analysis in the northern sky is now significantly
below , on average
lower than the sensitivity of the previously published analysis of four
years exposure. No significant clustering of neutrinos above background
expectation was observed, and implications for prominent neutrino source
candidates are discussed.Comment: 19 pages, 17 figures, 3 tables; ; submitted to The Astrophysical
Journa
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