On the possibilities of studying supernova neutrinos at Baksan

We consider the possibilities of studying a supernova collapse neutrino burst at Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) using the proposed 5-kt target-mass liquid scintillation spectrometer. Attention is given to the influence of mixing angle ? ₁₃ on the expected rates and spectra of neutrino events.     

Preliminary data on the neutron-neutron correlations in the nd-breakup reaction

Preliminary data on the dependence of the nd-breakup reaction yield on the energy of relative motion of two neutrons in the kinematic region, in which the final-state interaction is most pronounced, have been obtained. The measurements were performed on the RADEX neutron channel at the Institute for Nuclear Research, Russian Academy of Sciences, with neutron energies of 20–140 MeV, using a multidetector time-of-flight spectrometer. The data obtained make it possible to estimate the run time, which is necessary to determine the nn-scattering length with an error ～0.3–0.4 fm.     

Neutrino geophysics at baksan: On searches for antineutrinos and radiogenic-heat sources in the interior of the earth

Antineutrinos produced in the Earth (geoneutrinos) carry information that is of crucial importance for the understanding of the origin and evolution of our planet. It is shown that the Baksan Neutrino Observatory of the Institute for Nuclear Research (Moscow, Russian Academy of Sciences) may become one of the best laboratories for studying geoneutrinos with the aid of a large scintillation spectrometer. The article also presents a brief history of the development of concepts of the Earth as a source of antineutrinos—it dates back to 1960, spanning a period of nearly 45 years (1960–2004).     

Generation of electric fields by dust grains during the explosions of condensed explosive charges in air

Results are presented from two-dimensional numerical simulations of the generation of electric signals during the explosions of chemical explosive charges in air. The calculated results are compared with the data from experiments carried out under the auspices of the International Science and Technology Center (project no. 835) at the Institute of Geosphere Dynamics (Russian Academy of Sciences), the Research Institute of Pulsed Technique (the Ministry of Atomic Energy of the Russian Federation), and the Zababakhin All-Russia Research Institute of Technical Physics, Russian Federal Nuclear Center (the Ministry of Atomic Energy of the Russian Federation). The electric field is assumed to be generated by charged dust grains produced during the explosion of a condensed chemical explosive charge. Numerical predictions based on the dusty plasma model for describing the parameters of dust grains are found to agree satisfactorily with experiment.     

Cross section for the subthreshold fission of 236U

The cross section for ²³⁶U fission in the neutron-energy range E _n = 0.001–20 keV was measured by using the INR RAS (Institute of Nuclear Research, Russian Academy of Sciences, Moscow) LSDS-100 neutron spectrometer of the lead slowing-down spectrometer type. The resonance fission areas of the resonances at 5.45 eV and 1.28 keV were found, and the fission widths of these resonances were evaluated. The cross section for the ²³⁸U(n, f) fission process was measured, and the threshold sensitivity of the LSDS-100 to small values of fission cross sections was estimated. The well-known intermediate structure in the cross section for the neutron-induced subbarrier fission of ²³⁶U was confirmed.     

Phonons in ZrB<Subscript>12</Subscript>

The first results of measuring dispersion curves of acoustic phonons in the ZrB₁₂ superconductor are reported. The measurements have been conducted by the inelastic neutron scattering method on an ATOS three-axis spectrometer (IR-8, Russian Research Centre “Kurchatov Institute,” Moscow) at room temperature with a single crystal grown using a 99.5%-enriched ¹¹B isotope. The results obtained have been analyzed in terms of the lattice dynamics model proposed earlier for rare-earth dodecaborides. In this model, the constants of the force interaction of Zr atoms with one another and with the boron framework have been determined.     

Cross section for the subbarrier fission of <Superscript>244</Superscript>Cm

The cross section for ²⁴⁴Cm fission induced by neutrons of energy in the range between 0.07 eV and 20 keV was measured by using the lead slowing-down spectrometer (LSDS-100) of the Institute for Nuclear Research (Russian Academy of Sciences, Moscow). The parameters of the resonance areas were determined for the lowest eight s-wave neutron resonances, and the respective fission widths were evaluated. Also, the parameters of the intermediate structure in the cross section for the subbarrier fission of ²⁴⁴Cm nuclei were evaluated. The results were compared with available data and recommendations based on evaluations.     

Setup for studying quasi-free neutron-neutron scattering in the energy range of 20–60 MeV

A setup installed on the RADEX neutron beam channel (Institute for Nuclear Research, Russian Academy of Sciences) and designed to study quasi-free nn scattering in the n + d → p + n + n reaction is described. The setup is a two-arm time-of-flight spectrometer composed of scintillation neutron hodoscope (in the left arm), a scintillation neutron detector (in the right arm), and an active scintillation deuterated target for detecting protons. Secondary neutrons are detected at angles corresponding to the kinematic conditions of quasi-free nn scattering. Events are selected at low energies of the outgoing proton spectator. It is shown that data on neutron-neutron quasi-free scattering can be obtained in a wide range of primary-neutron energies.     

Cross section for <Superscript>246</Superscript>Cm subbarrier fission

The cross section for ²⁴⁶Cm fission induced by neutrons of energy in the range 0.1 eV-20 keV was measured by the neutron lead slowing-down spectrometer (LSDS-100) of the Institute for Nuclear Research (INR, Russian Academy of Sciences, Moscow). The parameters of the resonance area and of the fission width were evaluated for several low-lying s-wave neutron resonances. The parameters of the intermediate structure in the cross section for the subbarrier fusion of ²⁴⁶Cm nuclei were found. The results obtained in this way were compared with available experimental data and with recommended evaluated data.     

Possibility of determining microimpurities in materials using a activation measuring complex based on a photoneutron source

An activation measuring complex containing a W–Be photoneutron source of neutrons and a lowbackground gamma spectrometer is designed at the Russian Academy of Sciences Institute for Nuclear Research. The photoneutron source is mounted on the beam of a LUE-8 industrial electron linear accelerator with an electron energy of 7–8 MeV and contains a tungsten bremsstrahlung target, a photoneutron beryllium target, and a fast neutron moderator. The measuring component of the complex includes a detector made from high purity germanium, positioned inside a low-background chamber with active-passive protection. Neutron-activation analysis (NAA) is used to determine the content of microimpurities in a substance. A procedure for measuring ultralow contents of elements in aerosol filters is developed. Contents of Au, As, Sb, Mn, Fe, W, and other elements are measured in a variety of samples. The limits of detecting microimpurities in materials are estimated.     

Frequency plasma opening switches and their application in the technology of high-power accelerators

The main results reported here were obtained in a cycle of studies on plasma opening switches (POSs) and their application in frequency-pulse accelerators; those studies were carried out at the Russian Research Center, Kurchatov Institute from 1986 to 1997. That research was the basis for the development of frequency-pulse generators based on POS technology for quasi-constant generation of an electron beam and bremsstrahlung radiation. Several generators have been built for use in commercial radiation processing technologies. We give the parameters and basic circuit designs and discuss the prospects for further development of generators using POSs. The competitiveness in comparison with existing accelerating systems is examined. Thermonuclear Institute, Russian Research Center, Kurchatov Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 47–55, December, 1997.     

Investigating the influence of a Forbush decrease on the detected flux of high-energy muons

The effect of Forbush decreases was studied for a flux of high-energy muons with a threshold of 220 GeV detected by the Baksan Underground Scintillation Telescope (BUST) of the Institute for Nuclear Research, Russian Academy of Sciences.     

Pseudospark switches for the power supply circuits of pulsed lasers

A family of sealed-off low-pressure spark gap switches developed at the Institute of High Current Electronics (Tomsk) and at the Plasma Scientific Research Institute (Ryazan) with participation of researchers from the Physical Institute of the University of Erlangen (Germany) is described. The devices are of cermet construction, are capable of switching pulsed currents over wide ranges of amplitudes and durations, and have a number of unique characteristics. The principle of operation of the spark gap switches is described and their designs are given. The triggering circuits of the switches are considered. Institute of High-Current Electronics, Siberian Division of the Russian Academy of Sciences. Plazma Scientific Research Institute of Gas-Discharge Devices. Physical Institute of the University of Erlangen. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 97–105, April, 2000.     

Ultra-High Energy Gamma Ray Astronomy with the Carpet Air Shower Array at the Baksan Neutrino Observatory

Journal of Experimental and Theoretical Physics - The Carpet facility of the Baksan Neutrino Observatory (Institute for Nuclear Research of the Russian Academy of Sciences) was put into operation...     

Post Scriptum: Quantum Century and Our International Collaboration in Quantum Physics

Journal of Russian Laser Research - We present a short review of the history of researches in quantum and laser physics at the Lebedev Physical Institute and mention some aspects of international...     

Fundamental nuclear physics research at RFNC VNIIEF over 60 years

The role of fundamental nuclear physics research in development of nuclear weapons is considered. The main characteristics of the experimental facilities of the Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics are reported.     

Study of Vertical Ozone Distributions in the Stratosphere and Mesosphere at the Millimeter Wavelengths

We present the results of stratospheric and mesospheric ozone observations at the millimeter wavelengths. It is shown that the microwave remote sensing methods are important for studying the physical and chemical processes which play a significant role in the ozone-layer depletion. Examples of the results of ozone observations at 142.2 GHz by the spectrometer of the P. N. Lebedev Physical Institute of the Russian Academy of Sciences (LPI RAS) illustrate the high efficiency of radiophysical techniques for atmospheric-ozone research.     

Time-domain method of measurement of antenna parameters

A method is described to recover time far-field functions (and the corresponding set of radiation patterns in the frequency domain) by measurements of the pulsed field in the near region. The procedure and results of measurements of the characteristics of a 7-m mirror antenna with wideband feeds are presented. Radiophysical Research Institute, Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 5, pp. 614–624, May, 1998.     

Production of the Hg-199 isotope by the photochemical method

Researchers at the Russian Research Center Kurchatov Institute are developing a photochemical method of mercury isotope extraction. The method is based on oxidation of selectively excited mercury atoms in the presence of 1,3-butadiene. Along with the Hg-198, Hg-196, Hg-200, and Hg-202 isotopes, a Hg-199 isotope with a concentration as high as 90% has been produced for the first time.     

A neutron beam spectrometer based on a scintillation detector with n-γ pulse shape discrimination

A scintillation spectrometer with pulse shape separation of signals from neutrons and gamma quanta, installed on the RADEX neutron beam channel at the Institute for Nuclear Research is described. The need for n-γ separation is due to the presence of a substantial gamma background at the location of the spectrometer. To optimize n-γ separation, new parameters of the pulse shape separation and methods for calculating them are proposed. Significant improvement in the n-γ separation is obtained. Applying new parameters allows us to use information about only part of the scintillation pulse, enabling the operation of the spectrometer at high count rates and pulse pileup. Such a spectrometer can be used to monitor the RADEX neutron beam channel and determine the energy distribution of neutrons in the beam.