1,208 research outputs found
Physics Results from the AMANDA-B10 Neutrino Telescope
The data from the first year of operation of the 10-string, AMANDA-B10,
high-energy neutrino detector array at the South Pole have been analyzed and
searched for evidence of neutrinos from cosmic sources. Differently optimized
selection criteria have been used and limits on the flux of high-energy
neutrinos from a variety of objects have been derivedComment: 3 pages, 3 figures, presented at TAUP 2001, LNGS/Italy, September
2001. Fig. 3 updated and reference correcte
SUSY Resonances from UHE neutralinos in Neutrino Telescopes and in the Sky
In the Top-down scenarios, the decay of super-heavy particles
(m~10^{12-16}GeV), situated in dark-matter halos not very far from our Galaxy,
can explain the ultra-high-energy (UHE) cosmic-ray spectrum beyond the
Griesen-Zatasepin-Kuzmin cut-off. In the MSSM, a major component of the UHE
cosmic-ray flux at PeV-EeV energies could be given by the lightest neutralino
\chi, that is the lightest stable supersymmetric particle. Then, the signal of
UHE \chi's on earth might emerge over the interactions of a comparable neutrino
component. We compute the event rates for the resonant production of "right"
selectrons and "right" squarks in mSUGRA, when UHE neutralinos of energy larger
than 10^5 GeV scatter off electrons and quarks in an earth-based detector like
IceCube. When the resonant channel dominates in the total \chi-e,\chi-q
scattering cross section, the only model parameters affecting the corresponding
visible signal rates turn out to be the physical masses of the resonant
right-scalar and of the lightest neutralino. We compare the expected number of
supersymmetric events with the rates corresponding to the expected Glashow W
resonance and to the continuum UHE \nu-N scattering for realistic power-law
spectra. We find that the event rate in the leptonic selectron channel is
particularly promising, and can reach a few tens for a one-year exposure in
IceCube. Finally, we note that UHE neutralinos at much higher energies (up to
hundreds ZeV) may produce sneutrino resonances by scattering off relic
neutrinos in the Local Group hot dark halo. The consequent \tilde{\nu}-burst
into hadronic final states could mimic Z-burst events, although with quite
smaller conversion efficiency.Comment: 23 pages, 4 figures; one reference adde
Lowering IceCube's energy threshold for point source searches in the Southern Sky
Observation of a point source of astrophysical neutrinos would be a "smoking gun" signature of a cosmic-ray accelerator. While IceCube has recently discovered a diffuse flux of astrophysical neutrinos, no localized point source has been observed. Previous IceCube searches for point sources in the southern sky were restricted by either an energy threshold above a few hundred TeV or poor neutrino angular resolution. Here we present a search for southern sky point sources with greatly improved sensitivities to neutrinos with energies below 100 TeV. By selecting charged-current Îœ ÎŒ interacting inside the detector, we reduce the atmospheric background while retaining efficiency for astrophysical neutrino-induced events reconstructed with sub-degree angular resolution. The new event sample covers three years of detector data and leads to a factor of 10 improvement in sensitivity to point sources emitting below 100 TeV in the southern sky. No statistically significant evidence of point sources was found, and upper limits are set on neutrino emission from individual sources. A posteriori analysis of the highest-energy (~100 TeV) starting event in the sample found that this event alone represents a 2.8Ï deviation from the hypothesis that the data consists only of atmospheric background.Fil: Aartsen, M. G.. University of Adelaide; AustraliaFil: Abraham, K.. Technische UniversitĂ€t MĂŒnchen; AlemaniaFil: Ackermann, M.. Deutsches Elektronen-Synchrotron; AlemaniaFil: Adams, J.. University Of Canterbury; Nueva ZelandaFil: Aguilar, J. A.. UniversitĂ© Libre de Bruxelles; BĂ©lgicaFil: Golup, Geraldina Tamara. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de EnergĂa Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Patagonia Norte; ArgentinaFil: Wallace, A.. University of Adelaide; AustraliaFil: Wallraff, M.. Rwth Aachen University; AlemaniaFil: Wandkowsky, N.. University of Wisconsin; Estados UnidosFil: Weaver, Ch.. University of Alberta; CanadĂĄFil: Wendt, C.. University of Wisconsin; Estados UnidosFil: Westerhoff, S.. University of Wisconsin; Estados UnidosFil: Whelan, B. J.. University of Adelaide; AustraliaFil: Whitehorn, N.. University of California at Berkeley; Estados UnidosFil: Wickmann, S.. Rwth Aachen University; AlemaniaFil: Wiebe, K.. Johannes Gutenberg Universitat Mainz; AlemaniaFil: Wiebusch, C. H.. Rwth Aachen University; AlemaniaFil: Wille, L.. University of Wisconsin; Estados UnidosFil: Williams, D. R.. University of Alabama at Birmingahm; Estados UnidosFil: Wills, L.. Drexel University; Estados UnidosFil: Wissing, H.. University of Maryland; Estados UnidosFil: Wolf, M.. Stockholms Universitet; SueciaFil: Wood, T. R.. University of Alberta; CanadĂĄFil: Woschnagg, K.. University of California at Berkeley; Estados UnidosFil: Xu, D. L.. University of Wisconsin; Estados UnidosFil: Xu, X. W.. Southern University; Estados UnidosFil: Xu, Y.. Stony Brook University; Estados UnidosFil: Yanez, J. P.. Deutsches Elektronen-Synchrotron; AlemaniaFil: Yodh, G.. University of California at Irvine; Estados UnidosFil: Yoshida, S.. Chiba University; JapĂłnFil: Zoll, M.. Stockholms Universitet; Sueci
Light tracking through ice and water -- Scattering and absorption in heterogeneous media with Photonics
In the field of neutrino astronomy, large volumes of optically transparent
matter like glacial ice, lake water, or deep ocean water are used as detector
media. Elementary particle interactions are studied using in situ detectors
recording time distributions and fluxes of the faint photon fields of Cherenkov
radiation generated by ultra-relativistic charged particles, typically muons or
electrons.
The Photonics software package was developed to determine photon flux and
time distributions throughout a volume containing a light source through Monte
Carlo simulation. Photons are propagated and time distributions are recorded
throughout a cellular grid constituting the simulation volume, and Mie
scattering and absorption are realised using wavelength and position dependent
parameterisations. The photon tracking results are stored in binary tables for
transparent access through ANSI-C and C++ interfaces. For higher-level physics
applications, like simulation or reconstruction of particle events, it is then
possible to quickly acquire the light yield and time distributions for a
pre-specified set of light source and detector properties and geometries
without real-time photon propagation.
In this paper the Photonics light propagation routines and methodology are
presented and applied to the IceCube and Antares neutrino telescopes. The way
in which inhomogeneities of the Antarctic glacial ice distort the signatures of
elementary particle interactions, and how Photonics can be used to account for
these effects, is described.Comment: 22 pages, 8 Postscript figures, uses elsart.cl
The AMANDA Neutrino Telescope and the Indirect Search for Dark Matter
With an effective telescope area of order 10^4 m^2, a threshold of ~50 GeV
and a pointing accuracy of 2.5 degrees, the AMANDA detector represents the
first of a new generation of high energy neutrino telescopes, reaching a scale
envisaged over 25 years ago. We describe its performance, focussing on the
capability to detect halo dark matter particles via their annihilation into
neutrinos.Comment: Latex2.09, 16 pages, uses epsf.sty to place 15 postscript figures.
Talk presented at the 3rd International Symposium on Sources and Detection of
Dark Matter in the Universe (DM98), Santa Monica, California, Feb. 199
Muon Track Reconstruction and Data Selection Techniques in AMANDA
The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy
neutrino telescope operating at the geographic South Pole. It is a lattice of
photo-multiplier tubes buried deep in the polar ice between 1500m and 2000m.
The primary goal of this detector is to discover astrophysical sources of high
energy neutrinos. A high-energy muon neutrino coming through the earth from the
Northern Hemisphere can be identified by the secondary muon moving upward
through the detector. The muon tracks are reconstructed with a maximum
likelihood method. It models the arrival times and amplitudes of Cherenkov
photons registered by the photo-multipliers. This paper describes the different
methods of reconstruction, which have been successfully implemented within
AMANDA. Strategies for optimizing the reconstruction performance and rejecting
background are presented. For a typical analysis procedure the direction of
tracks are reconstructed with about 2 degree accuracy.Comment: 40 pages, 16 Postscript figures, uses elsart.st
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.
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
Shower Power: Isolating the Prompt Atmospheric Neutrino Flux Using Electron Neutrinos
At high energies, the very steep decrease of the conventional atmospheric
component of the neutrino spectrum should allow the emergence of even small and
isotropic components of the total spectrum, indicative of new physics, provided
that they are less steeply decreasing, as generically expected. One candidate
is the prompt atmospheric neutrino flux, a probe of cosmic ray composition in
the region of the knee as well as small- QCD, below the reach of collider
experiments. A second is the diffuse extragalactic background due to distant
and unresolved AGNs and GRBs, a key test of the nature of the highest-energy
sources in the universe. Separating these new physics components from the
conventional atmospheric neutrino flux, as well as from each other, will be
very challenging. We show that the charged-current {\it electron} neutrino
"shower" channel should be particularly effective for isolating the prompt
atmospheric neutrino flux, and that it is more generally an important
complement to the usually-considered charged-current {\it muon} neutrino
"track" channel. These conclusions remain true even for the low prompt
atmospheric neutrino flux predicted in a realistic cosmic ray scenario with
heavy and varying composition across the knee (Candia and Roulet, 2003 JCAP
{\bf 0309}, 005). We also improve the corresponding calculation of the neutrino
flux induced by cosmic ray collisions with the interstellar medium.Comment: 15 pages, 4 figures. Minor modifications, version accepted for
publication in JCA
The AMANDA Neutrino Telescope
With an effective telescope area of order m for TeV neutrinos, a
threshold near 50 GeV and a pointing accuracy of 2.5 degrees per muon
track, the AMANDA detector represents the first of a new generation of high
energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We
describe early results on the calibration of natural deep ice as a particle
detector as well as on AMANDA's performance as a neutrino telescope.Comment: 12 pages, Latex2.09, uses espcrc2.sty and epsf.sty, 13 postscript
files included. Talk presented at the 18th International Conference on
Neutrino Physics and Astrophysics (Neutrino 98), Takayama, Japan, June 199
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