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R. Wischnewski

Publications and source records attributed to R. Wischnewski.

47 records · Page 3Linked to original sources
arXiv2006

The BAIKAL Neutrino Experiment: From NT200 to NT200+

The Baikal Neutrino Telescope has been operating in its NT200 configuration since April, 1998. The telescope has been upgraded in April, 2005, to the 10 Mton scale detector NT200+. It's main physics goal is the detection of signals from high energy neutrino cascades. NT200+ reaches a 3-year sensitivity of 2 \times 10^{-7}cm^{-2}s^{-1}sr^{-1}GeV for an all-flavor diffuse cosmic E^{-2} neutrino flux for energies 10^2 TeV ÷10^5 TeV. Desgin and sensitivity of NT200+ are described. NT200+ is forming the basic building block of a future km3-scale (Gigaton-Volume) Baikal Telescope. Research and development work on that next stage detector has started.

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arXiv2005

Search for a diffuse flux of high-energy neutrinos with the NT200 neutrino telescope

We present the results of a search for high energy extraterrestrial neutrinos with the Baikal underwater Cherenkov detector NT200, based on data taken in 1998 - 2002 (1038 live days).Upper limits on the diffuse fluxes of ν_e+ν_μ+ν_τ, predicted by several models of AGN-like neutrino sources, are derived. For an E^{-2} behavior of the neutrino spectrum, our limit is E^2 Φ_ν(E)<8.1 10^{-7} cm^{-2} s^{-1} sr^{-1} GeV over a neutrino energy range 2 10^4 - 5 10^7 GeV covering 90% of expected events. The upper limit on the resonant \barν_e diffuse flux is Φ_{\barν_e} < 3.3 10^{-20} cm^{-2}s^{-1}sr^{-1}GeV^{-1}.

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arXiv2005

Baikal neutrino telescope NT200+ : Upgrade of data acquisition and time calibration systems

The Baikal neutrino telescope NT200, operating since 1998, has been upgraded in spring 2005 to NT200+. This telescope with 3 additional outer strings at 100 m radius from the center encloses a geometric volume of 5 Mtons. We describe the modernized data acquisition and control system, which allows for higher bandwidth, full multiplexing of data and control streams over a single cable to shore, redundant system components and underwater data pre-processing. To calibrate all time offsets between new distant strings and the central telescope on the nsec-scale, a new external laser unit with a powerful N2-Dye laser and a light diffusor, has been developed. This laser is also used to tune reconstruction techniques for pointlike showers with energies from 20 TeV to 10 PeV.

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arXiv2005

The Baikal Neutrino Telescope - Results and Plans

New results from the Baikal neutrino telescope NT200, based on the first 5 years of operation (1998-2003), are presented. We derive an all-flavor limit on the diffuse flux of astrophysical neutrinos between 20 TeV and 50 PeV, extract an enlarged sample of high energy muon neutrino events, and obtain limits on the flux of high energy atmospheric muons. In 2005, the upgraded telescope NT200+ will be commissioned: 3 additional distant strings with only 12 photo-multipliers each will rise the effective volume to 20 Mton at 10 PeV for this largest running neutrino telescope in the Northern hemisphere.

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arXiv2004

The Tunka Experiment: Towards a 1-km^2 Cherenkov EAS Array in the Tunka Valley

The project of an EAS Cherenkov array in the Tunka valley/Siberia with an area of about 1 km^2 is presented. The new array will have a ten times bigger area than the existing Tunka-25 array and will permit a detailed study of the cosmic ray energy spectrum and the mass composition in the energy range from 10^15 to 10^18 eV.

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arXiv2004

Primary Energy Spectrum and Mass Composition Determined with the Tunka EAS Cherenkov Array

New results of 300 hours of operation of the Tunka array are presented. An improved parametrization of the Cherenkov light lateral distribution function (LDF), based on CORSIKA Monte Carlo simulations and the experiment QUEST, has been used for the reconstruction of EAS parameters. The corrected energy spectrum in the knee region is obtained. The mean depth of the EAS maximum has been derived both from the analysis of LDF steepness and the FWHM of Cerenkov light pulse. The mean mass composition around the knee is estimated.

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arXiv2003

Results from the BAIKAL neutrino telescope

We review the present status of the Baikal Neutrino Project, present updated results on the search for high energy extraterrestrial neutrinos, fast magnetic monopoles and neutrinos induced by WIMP annihilation in the center of the Earth and compare the recorded atmospheric neutrino flux to predictions. We describe the moderate upgrade of NT-200 toward $\sim$10 Mton scale detector NT-200 +.

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arXiv2002

The AMANDA-II Neutrino-Telescope

The AMANDA-II telescope at the South Pole is constructed of 677 optical modules at 19 strings. We describe the observation of atmospheric neutrinos with the first stage 10-string detector AMANDA-B10, which establishes AMANDA as a working neutrino telescope. The expected performance for the AMANDA-II detector is discussed.

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arXiv1996

Analog Optical Transmission of Fast Photomultiplier Pulses Over Distances of 2 km

New LED-transmitters have been used to develop a new method of fast analog transmission of PMT pulses over large distances. The transmitters, consisting basically of InGaAsP LEDs with the maximum emission of light at 1300 nm, allow the transmission of fast photomultiplier pulses over distances of more than 2 km. The shape of the photomultiplier pulses is maintained, with an attenuation less than 1 dB/km. Typical applications of analog optical signal transmission are surface air shower detectors and underwater/ice neutrino experiments, which measure fast Cherenkov or scintillator pulses at large detector distances to the central DAQ system.

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