34 research outputs found
Registration of atmospheric neutrinos with the Baikal neutrino telescope
We present first neutrino induced events observed with a deep underwater
neutrino telescope. Data from 70 days effective life time of the BAIKAL
prototype telescope NT-96 have been analyzed with two different methods. With
the standard track reconstruction method, 9 clear upward muon candidates have
been identified, in good agreement with 8.7 events expected from Monte Carlo
calculations for atmospheric neutrinos. The second analysis is tailored to
muons coming from close to the opposite zenith. It yields 4 events, compared to
3.5 from Monte Carlo expectations. From this we derive a 90 % upper flux limit
of 1.1 * 10^-13 cm^-2 sec^-1 for muons in excess of those expected from
atmospheric neutrinos with zenith angle > 150 degrees and energy > 10GeV.Comment: 20 pages, 11 figure
Energy calibration of large underwater detectors using stopping muons
We propose to use stopping cosmic-ray muons in the energy calibration of planned and deployed large underwater detectors. The method is based on the proportionality between the incident muon energy and the length of the muon path before it stops. Simultaneous measurements of the muon path and the amplitude of the signal from the photomultiplier tubes allow a relation between the energy deposited in the sensitive volume of the detector and the observed signal to be derived, and also provide a test of detector simulations. We describe the proposed method and present the results of simulations
The Lake Baikal neutrino experiment
We rewiew the present status of the Baikal Neutrino Project and present the
results of a search for high energy neutrinos with the detector intermediate
stage NT-96.Comment: 3 pages, 2 figures, to appear in the Proceedings of Sixth
International Workshop on Topics in Astroparticle and Underground Physics
(TAUP99), September 6-10, 1999, Pais, Franc
Status of the Lake Baikal Experiment
We review the present status of the Baikal Underwater Neutrino Experiment and
report on neutrino events recorded with the detector stages NT-36 and NT-96.Comment: 5 pages, 4 PostScript figures, uses here.sty and mine.sty, submitted
to the Proc. of 5th Int. Workshop on Topics in Astroparticle and Underground
Physics (LNGS INFN, Assergi, September 7-11, 1997
Cosmic Neutrinos and the Energy Budget of Galactic and Extragalactic Cosmic Rays
Although kilometer-scale neutrino detectors such as IceCube are discovery
instruments, their conceptual design is very much anchored to the observational
fact that Nature produces protons and photons with energies in excess of
10^{20} eV and 10^{13} eV, respectively. The puzzle of where and how Nature
accelerates the highest energy cosmic particles is unresolved almost a century
after their discovery. We will discuss how the cosmic ray connection sets the
scale of the anticipated cosmic neutrino fluxes. In this context, we discuss
the first results of the completed AMANDA detector and the science reach of its
extension, IceCube.Comment: 13 pages, Latex2e, 3 postscript figures included. Talk presented at
the International Workshop on Energy Budget in the High Energy Universe,
Kashiwa, Japan, February 200
The Oscillation Probability of GeV Solar Neutrinos of All Active Species
In this paper, I address the oscillation probability of O(GeV) neutrinos of
all active flavours produced inside the Sun and detected at the Earth. Flavours
other than electron-type neutrinos may be produced, for example, by the
annihilation of WIMPs which may be trapped inside the Sun. In the GeV energy
regime, matter effects are important both for the ``1-3'' system and the
``1-2'' system, and for different neutrino mass hierarchies. A numerical scan
of the multidimensional three-flavour parameter space is performed,
``inspired'' by the current experimental situation. One important result is
that, in the three-flavour oscillation case, P{alpha,beta} is different from
P{beta,alpha} for a significant portion of the parameter space, even if there
is no CP-violating phase in the MNS matrix. Furthermore, P{mu,mu} has a
significantly different behaviour from P{tau,tau}, which may affect
expectations for the number of events detected at large neutrino telescopes.Comment: 38 pages, 10 figure
The Baikal Deep Underwater Neutrino Experiment: Results, Status, Future
We review the present status of the Baikal Underwater Neutrino Experiment and
present results obtained with the various stages of the stepwise increasing
detector: NT-36 (1993-95), NT-72 (1995-96) and NT-96 (1996-97). Results cover
atmospheric muons, first clear neutrino events, search for neutrinos from WIMP
annihilation in the center of the Earth, search for magnetic monopoles, and --
far from astroparticle physics -- limnology.Comment: Talk given at the Int. School on Nuclear Physics, Erice, Sept.199
Ultra-High Energy Neutrino Fluxes and Their Constraints
Applying our recently developed propagation code we review extragalactic
neutrino fluxes above 10^{14} eV in various scenarios and how they are
constrained by current data. We specifically identify scenarios in which the
cosmogenic neutrino flux, produced by pion production of ultra high energy
cosmic rays outside their sources, is considerably higher than the
"Waxman-Bahcall bound". This is easy to achieve for sources with hard injection
spectra and luminosities that were higher in the past. Such fluxes would
significantly increase the chances to detect ultra-high energy neutrinos with
experiments currently under construction or in the proposal stage.Comment: 11 pages, 15 figures, version published in Phys.Rev.
Cosmic Neutrinos from the Sources of Galactic and Extragalactic Cosmic Rays
Although kilometer-scale neutrino detectors such as IceCube are discovery
instruments, their conceptual design is very much anchored to the observational
fact that Nature produces protons and photons with energies in excess of 10^20
eV and 10^13 eV, respectively. The puzzle of where and how Nature accelerates
the highest energy cosmic particles is unresolved almost a century after their
discovery. From energetics considerations we anticipate order 10~100 neutrino
events per kilometer squared per year pointing back at the source(s) of both
galactic and extragalactic cosmic rays. In this context, we discuss the results
of the AMANDA and IceCube neutrino telescopes which will deliver a
kilometer-square-year of data over the next 3 years.Comment: 8 pages, 4 figure
New hadrons as ultra-high energy cosmic rays
Ultra-high energy cosmic ray (UHECR) protons produced by uniformly
distributed astrophysical sources contradict the energy spectrum measured by
both the AGASA and HiRes experiments, assuming the small scale clustering of
UHECR observed by AGASA is caused by point-like sources. In that case, the
small number of sources leads to a sharp exponential cutoff at the energy
E<10^{20} eV in the UHECR spectrum. New hadrons with mass 1.5-3 GeV can solve
this cutoff problem. For the first time we discuss the production of such
hadrons in proton collisions with infrared/optical photons in astrophysical
sources. This production mechanism, in contrast to proton-proton collisions,
requires the acceleration of protons only to energies E<10^{21} eV. The diffuse
gamma-ray and neutrino fluxes in this model obey all existing experimental
limits. We predict large UHE neutrino fluxes well above the sensitivity of the
next generation of high-energy neutrino experiments. As an example we study
hadrons containing a light bottom squark. These models can be tested by
accelerator experiments, UHECR observatories and neutrino telescopes.Comment: 17 pages, revtex style; v2: shortened, as to appear in PR