Vladimir A. Tsarev

Problems and horizons of the search for tracks of heavy and superheavy nuclei in olivine crystals from meteorites (OLIMPIYA project)

In this paper, we consider the nuclear-physical and astrophysical aspects of investigations associated with the search for heavy and superheavy nuclei in the composition of cosmic rays. We also discuss the potentiality of searching for tracks of these nuclei in the olivine crystals found in meteorites with the use of the completely automated PAVICOM setup, which was designed for the scanning and processing of tracks of particles.

Detection of ultrahigh-energy cosmic rays and neutrinos by radio method using artificial lunar satellites

An estimate of the feasibility of the ultrahigh-energy cosmic ray and neutrino detection using a lunar satellite-borne radio receiver is presented. The data obtained in the proposed experiment will make resolving the current contradictions in the ultrahigh-energy cosmic ray spectra measured with the major ground-based instruments possible. Moreover, they will enable us to considerably extend the accessible energy range and to check predictions of various models of the origin of the highest-energy particles in the Universe. At the same time the lunar radio detector provides a means of searching for ultrahigh-energy neutrinos with a high sensitivity combined with a very large target effective mass.

Calibration measurements of the characteristics of tracks from superheavy nuclei in olivine crystals from meteorites

To identify the charge of detected cosmic ray nuclei, it is necessary that the dynamic and geometric parameters of tracks (the etching rate of a nuclear track, as well as the length and the diameter of the track channel) be determined with a high accuracy. Results of the experimental investigations of tracks produced in olivine crystals from the Marjalahti pallasite by accelerated Xe and U nuclei are presented. These investigations were performed as part of the Olimpiya project. It is shown that the etching rate and the fully etched track length are independent of the track orientation relative to the crystallographic symmetry axes of each olivine crystal under investigation.

Two-channel scheme for dark matter particle detection based on a low-temperature magnetic calorimeter

Problems of dark matter (DM) particle detection are briefly reviewed. An original two-channel scheme for direct detection of cosmic DM particles is proposed. This scheme is based on a superlow-temperature calorimeter which includes a nuclear spin system whose magnetic response is measured by a quantum interferometer (SQUID). Low threshold and the capability for efficiently suppressing the recoil-electron background are the most important advantages of the proposed scheme. They make it possible to detect DM particles in the range of extremely low recoil energies and carry out direct DM search with high sensitivity.

Simulation of an experiment on detecting ultra-high-energy particles with regard to the structure of the lunar soil surface layer

The feasibility of using the lunar orbital radio detector to detect radio signals from cascades initiated by ultra-high-energy cosmic rays interacting with the lunar regolith is studied. Simulation by the Monte Carlo method demonstrates that, with the regolith thickness randomly distributed in the range 2–12 m, the detection of radio signals reflected from the lower boundary of the regolith (for particle energies W ≥ 1020 eV) increases the number of valid events severalfold. The additional contribution due to the reflected radio-frequency radiation greatly enhances the scientific potential of experiments with the lunar orbital radio detector.

Technique for determining the charge of cosmic ray nuclei by tracks in olivine crystals from meteorites

A technique for identifying the charge of cosmic ray nuclei, based on measurements of the length and average etch rate of tracks chemically etched in olivine crystals from the Marjalahti pallasite is described.

Search for neutrino oscillations vμ → vτ in CERN → Gran Sasso high-energy neutrino beam (the OPERA experiment)

The main purpose of the OPERA experiment is the direct observation of neutrino oscillations (vμ → vτ) in the vμ beam from the CERN accelerator through the direct detection of τ leptons in nuclear emulsions at the Gran Sasso National Underground Laboratory. Some aspects of the use of the Russian PAVICOM facility for processing and analyzing the data obtained from the OPERA experiment are discussed.

Adapting and testing PAVICOM facility for treatment of OPERA experimental data

The Completely Automatic Measuring Complex (PAVICOM) was constructed in 2000th year in the Lebedev Physical Institute and started for track-detector data processing in the field of nuclear, high energy and cosmic ray physics. Here an improvement of PAVICOM facility that enabled processing OPERA experiment data is presented. The scanning facility hardware was upgraded as well as new microscope controlling software was developed. Now it consists of LOMO microscope; Carl Zeiss scanning stage (Movement range: X = 120mm, Y = 100mm, accuracy 0.25um for X, Y and 3.46 x 10-3um for Z); MCU-26 stage controller; CMOS-camera Mikrotron MC1310; a server with 2 Xeon processors for data treatment, equipped with Matrox Odyssey Xpro board for image grabbing and first processing. Data treatment and reconstruction software was adapted to work with the standard OPERA data on PAVICOM and provides now ability for on-line emulsions detectors treatment: while one field of view is processed, the next one is scanning. Because the main resource-intensive operation is now carried out on the Matrox board, the processing time is limited only to the speed of the stage. This is what allows using PAVICOM for OPERA emulsion data processing. Also some test processing results of OPERA emulsions are presented.

Hybrid method for detecting cascades produced by ultrahigh-energy cosmic particles using a circumlunar satellite

A hybrid method for detecting cosmic rays and neutrino cascades using the radio method and the conventional method for detecting cascade particles was proposed. Cascades produced in the lunar soil near the surface by ultrahigh-energy cosmic rays and neutrinos in the energy range of 1 GeV–100 TeV, coming from above at different angles, were calculated. The calculated energy and angular distributions were extrapolated to the energy region of 1020 eV. Using these results, the detection threshold was estimated as 1020 eV which is approximately identical to the threshold for the radio detector previously considered by the authors.

Contemporary status of the OPERA experiment for detecting νμ → ντ oscillations in a νμ beam

The first results of the physical stage of the OPERA experiment in 2007, when observation of oscillations of gvμ into gvτ started, are discussed. Thirty eight events related to neutrino interactions in emulsion blocks (bricks) are found. The underground muon spectrum and the μ+/μ− ratio are obtained. The results of using detachable emulsion packs (changeable sheets) and accuracy of predictions of neutrino interaction vertices in emulsion layers are discussed. The results of the hardware and software upgrade of the automatic emulsion scanning system PAVIKOM are reported.