58 research outputs found
On the Velocity of Light Signals in the Deep Underwater Neutrino Experiments
During the last few years deep underwater neutrino telescopes of a new
generation with dimensions close to 100 m or more were taken into operation.
For the correct track reconstruction and for the interpretation of light pulses
from calibration lasers one has to use the group velocity for light signals.
The difference between group velocity leads to an additional delay of about 10
ns for a distance of 100 m between light source and photjmultiplier. From the
time of the appearance of the first projects of deep underwater neutrino
telescopes in the middle of 70th this fact was never mentioned in the
literature.Comment: 4 pages, 2 figure
The optical module of the Baikal deep underwater neutrino telescope
A deep underwater Cherenkov telescope has been operating since 1993 in stages
of growing size at 1.1 km depth in Lake Baikal. The key component of the
telescope is the Optical Module (OM) which houses the highly sensitive
phototube QUASAR-370. We describe design and parameters of the QUASAR-370, the
layout of the optical module, the front-end electronics and the calibration
procedures, and present selected results from the five-year operation
underwater. Also, future developments with respect to a telescope consisting
from several thousand OMs are discussed.Comment: 30 pages, 24 figure
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
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
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
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
The cosmic ray positron excess and neutralino dark matter
Using a new instrument, the HEAT collaboration has confirmed the excess of
cosmic ray positrons that they first detected in 1994. We explore the
possibility that this excess is due to the annihilation of neutralino dark
matter in the galactic halo. We confirm that neutralino annihilation can
produce enough positrons to make up the measured excess only if there is an
additional enhancement to the signal. We quantify the `boost factor' that is
required in the signal for various models in the Minimal Supersymmetric
Standard Model parameter space, and study the dependence on various parameters.
We find models with a boost factor greater than 30. Such an enhancement in the
signal could arise if we live in a clumpy halo. We discuss what part of
supersymmetric parameter space is favored (in that it gives the largest
positron signal), and the consequences for other direct and indirect searches
of supersymmetric dark matter.Comment: 11 pages, 6 figures, matches published version (PRD
The Lake BAIKAL Neutrino Project: Status Report
A first large deep underwater detector for muons and neutrinos, NT-200, is currently under construction in Lake Baikal. Part of the detector consisting of 36 optical modules (NT-36) has been operated over nearly 2 years in 1993 and 1994. With this detector not only methodical questions are investigated, but also some problems in the field of astroparticle physics, cosmic ray physics and limnology. In March 1995, a 72-PMT version was deployed. We describe the construction of the detector and the present status of the project and review some of the results. 1 The NT-200 Detector The Baikal Neutrino Telescope [1] is being deployed in the Siberian Lake Baikal, about 3.6 km from shore at a depth of 1.1 km. In April 1993 we put into operation the stationary 3-string detector NT-36, since April 1994 a modified version of NT-36 was taking data. An array carrying 72 PMTs has been deployed in March 1995. These arrays are steps towards the Neutrino Telescope NT-200 which will consist of 192 opti..
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