The quest for the ideal photodetector for the next generation deep-underwater neutrino telescopes

We review photodetectors used in present running neutrino telescopes. After a brief historical discourse, the photodetector requirements for the next generation deep underwater neutrino telescopes are discussed. It is shown that large area vacuum hybrid phototubes are the closest to the ideal photodetector for such kind of applications when compared with other vacuum phototubes.Comment: 5 pages, 5 figure

On the detection of relativistic magnetic monopoles by deep underwater and underice neutrino telescopes

I present here some reflections and very speculative remarks on the detection of relativistic magnetic monopoles by currently operating deep underwater/ice neutrino telescopes.Comment: To appear in the proceedings of the 5th International Workshop RICH200

Measurements of group velocity of light in the lake Baikal water

The results of direct measurements of group velocity of light in the lake Baikal water at the depth of 1100 m are presented. The lake Baikal water dispersion has been measured at three wavelengths: 370 nm, 470 nm and 525 nm. The results are in a rather good agreement with theoretical predictions.Comment: 4 pages, 5 figures, talk presented at RICH2002, to be published in NIMA; misprints corrected in formula at page

An observation of a new class of afterpulses with delay time in the range of 70-200 microseconds in classical vacuum photomultipliers

We present results of the first observation of afterpulses with extremely long (~120 microseconds) delay time from the main pulse in 8 inch classical vacuum photomultipliers.Comment: To be published in NIM

Photoelectron backscattering in vacuum phototubes

In this article we describe results of a photoelectron backscattering effect in vacuum phototubes: classical photomultipliers (PMT) and hybrid phototubes (PH). Late pulses occurring in PMTs are attributed to the photoelectron backscattering and distinguished from pulses due to an anode glow effect. The late pulses are measured in a number of PMTs and HPs with various photocathode sizes covering 1-50 cm range and different types of the first dynode materials and construction designs. It is shown that the late pulses are a generic feature of all vacuum photodetectors - PMTs and PHs and they don't deteriorate dramatically amplitude and timing responses of vacuum phototubes

On the history of photomultiplier tube invention

In this very short note we review some historical aspects of photomultiplier tube invention. It is our tribute to the memory of great Soviet-Russian physicist and engineer Leonid Aleksandrovitch Kubetsky whose life and scientific achievements are described briefly. Particular efforts are made to shed light on a controversial issue of who invented the first photomultiplier tube. It is asserted that if to recognize L.A.Kubetsky's priority on the photomultiplier tube invention the last Beaune Conference would be held on the eve of the 75th Anniversary of that great event.Comment: Presented at the 4th Beaune Conference on New Development in Photodetection, Beaune France, 19-24 June 200

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

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 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