G. N. Dudkin

The Baikal underwater neutrino telescope: Design, performance and first results

Abstract A first deep underwater detector for muons and neutrinos, NT-200 , is currently under construction in Lake Baikal. Part of the detector, NT-36 , with 36 photomultiplier tubes at three strings, has been installed in 1993. This array allowed for the first time a three-dimensional mapping of Cherenkov light deep underwater. Since then, various arrays have been almost continuously taking data. Presently a 96-PMT array is operating. We describe the NT-200 detector design and present results obtained with NT-36 .

Measurement of the astrophysical S factor for dd interaction at ultralow deuteron-collision energies using the inverse Z pinch

This paper is devoted to measurement of the astrophysical S factor and cross sections of the d + d → 3He + n reaction at ultralow deuteron-collision energies. Formation of the flow of the accelerated deuterons incident on the CD2 solid-state target was made within the scheme of the inverse Z pinch. The liner in the initial state was a hollow supersonic deuterium jet of radius of 15 mm and length of 20 mm. The experiment was carried out at the pulsed high-current accelerator (I=950 kA, τ=80 ns) of the Institute of High-Current Electronics (Tomsk, Russia). Measurement of the deuteron energy distribution was performed through an analysis of the time distributions of the intensity of the liner radiation (Hα and Hβ lines) generated during the liner radial movement from the axis. Recording of this radiation was carried out by optical detectors placed along the direction of the liner moving from its axis. The measured value of the astrophysical S factor for the dd reaction at the average deuteron collision energy Ecoll=3.69 keV was equal to S(Ecoll=3.69 keV)=58.2±18.1 keV b. The dd-reaction cross section calculated using the found value of the S factor and known representation of the reaction cross section as the product of the barrier factor and the astrophysical S factor was σddn(Ecoll=3.69 keV)=(1.33±0.41)×10−30 cm2.

Study of the pd reaction at ultralow energies using hydrogen liner plasma

AbstractThe pd reaction (pd → He + γ (5.5 MeV)) is studied in the astrophysical energy collision range of protons with deuterons using the hydrogen liner in the inverse Z-pinch configuration at the pulsed power generator MIG (HCEI, Tomsk). Fundamental characteristics of this and other light-nucleus reactions at ultralow energies are important for problems of basic physics and astrophysics. The knowledge of the energy distribution of the nuclei participating in these reactions is important due to their exponential type of dependence on the collision energy. Two experimental techniques were designed and tested for recovering the energy distribution of liner protons incident on the CD2 target by using optical detectors and ion collectors. It is shown that the combined use of these two techniques could provide relevant information on the energy distribution of the accelerated protons in the liner. The estimates of the upper limits for the astrophysical S factor and effective cross section of the pd reaction in the proton-deuteron collision energy range of 2.7–16.7 keV are obtained:

Does the coherent bremsstrahlung of fission fragments exist

\bar S_{pd} (E_{pd} = 10.2 keV) \leqslant 2.5 \times 10^{ - 7} MeV b;\overline \sigma _{pd} (2.7 \leqslant E_{pd} \leqslant 16.7 keV) \leqslant 4 \times 10^{ - 33} cm^2

Deuterium Liner and Multiparametric Studies of the Formation of an Inverse Z-Pinch

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Results of search for heavy neutron clusters in nuclear fission

An experiment on search for heavy neutron clusters in fission of 235U nuclei has been carried out on a nuclear reactor. The method of searching for neutron clusters is based on irradiation of tellurium dioxide and lead oxide targets in reactor channels near the active zone and far from it. The method of γ-spectrometric analysis of irradiated targets was used to search for nuclei whose occurrence in the targets cannot be explained by other nuclear reactions, except for the reactions of original target nuclei with neutron clusters. The reactions of tellurium and lead nuclear fission by neutron clusters (nuclei) and direct capture of neutron clusters have been revealed.

Simulation of the formation of accelerating structures and ion acceleration in the collision of magnetosonic shock waves

The spectrum of γ rays from the neutron-induced fission of 235U nuclei has been studied in a range of 10–90 MeV. The experiment has been carried out in the horizontal experimental channel of a nuclear reactor. The energy spectrum was measured using a single-crystal NaI(T1) spectrometer. The data on the energy dependence of the yield of γ rays have been obtained in a range of 12–38 MeV. The upper limit on the probability of the emission of γ rays has been determined for a range of 38–90 MeV. It has been shown that the experimental data are inconsistent with available models attributing the yield of γ rays in this energy range to the coherent bremsstrahlung of fission fragments in the Coulomb field.

A setup with Cherenkov total absorption spectrometers with large aperture for slow π0- and η-meson detection

Abstract We review the historical development and the present status of the Baikal experiment, and sketch the 6-string detector “NT-200”, which is planned to be deployed until 1993 and to study neutrino astrophysics cosmic rays and particle physics.