The concentration and distribution of U were measured in zircon samples separated from the streambed sediments collected at different sites along the rivers of northern Vietnam using semiconductor alpha spectrometry and alpha- and fission-track autoradiography. Based on the absolute U content and distribution, we distinguished two groups of zircon grains of different origin. Group 1 zircons have relatively low and uniform U contents ranging from 280 to 440 μg/g. Group 2 zircons are characterized by heterogeneous U distribution and U contents ranging from 490 to 2040μg/g. The determination of absolute alpha activity values and alpha spectrometric characteristics for a number of group 2 zircon grains indicated the presence of relatively short-lived alpha-emitters. These radionuclides are probably 210Po, 232U, 236Pu, 241Am, and 243Am, and all of them can originate exclusively from anthropogenic sources. A comparison of the observed alpha activity values for group 2 zircons with those of group 1 zircons and zircons separated from the suspended colloids in river water samples provided conclusive evidence for traces of anthropogenic radioactive contamination in the Lao Cai, Yen Bai, Tuyen Quang, Thac Ba, Viet Tri, and Hanoi streams flowing in the Song Hong (Red) and Song Da (Black) river basins of northern Vietnam and sourced in the southern regions of the neighboring state.

Results for some heavy metals concentrations and gamma-spectrometric investigations of the radioecology of environment in the two main river territories of the Central and South Vietnam regions are presented. There were found no water or filtrate matter that could indicate on the presence of the technological Cs-137 or Am-241 nuclides in the samples under investigation. Limit values of Th and U concentrations in zircon samples are within the variations of the values for the nature rock zircons. The Th/U relation parameter values in the range of 2.4 - 6.9 are consistent within error of measurement with the ZGI-GM standard mountain-granite.

Results from the experimental search for and identification of tracks from the superheavy and transuranium nuclei of galactic cosmic rays in pallacite olivine crystals, conducted as part of project OLIMPIA [1], are presented. To date, 170 crystals from Marjalahti and Eagle Station pallacites have been processed and 6800 tracks corresponding to nuclei with charges Z > 55 have been found; 45 of these are from nuclei with charges of 88 < Z < 92 and three super-long ones were produced by nuclei with Z > 105. The charge of one of these nuclei is estimated in the first approximation as Z = 119(+10,−6). Our data confirm the hypothesis of islands of stability for natural trans-Fermi nuclei.

Представлены результаты минералогического, петрографического, элементного и изотопного анализа метеорита Челябинск и их геохимическая интерпретация. Показано, что метеорит относится к группе LL5 обыкновенных хондритов и характеризуется умеренной степенью ударного метаморфизма (S4). Метеорит Челябинск содержит значительное (около одной трети объема) количество ударно-расплавного материала. Этот материал по составу близок к основной части метеорита. Результаты изотопного анализа позволяют предполагать, что ударное событие в истории образования метеорита произошло приблизительно 290 млн. лет назад.

The charge distribution of approximately 6000 nuclei with charge numbers above 55 in galactic cosmic rays has been obtained in the OLIMPIYA project. Three superheavy nuclei with the charge numbers in the range 105 < Z < 130 have been detected. The regression analysis has provided a more accurate estimate of the charge number of one of these nuclei (119 −6 +10 with a probability of 95%). Such nuclei should form stability islands. Their detection in nature confirms theoretical predictions and justifies efforts for their synthesis under terrestrial conditions. The model calculations performed in this work possibly can explain the results of some experiments on the investigation of the charge composition of cosmic rays in which particles with charge numbers in the range 94 < Z < 100 were detected (they cannot enter into the composition of primary cosmic radiation because their lifetime is very short). The calculations indicate that events with Z > 92 are due to the fragmentation of heavier nuclei from the stability island, rather than to methodical inaccuracies or fault of instruments. Several such events have been revealed. Thus, the track method makes it possible to obtain the results very important for understanding of the physical picture of the world. The results obtained within the OLIMPIYA project show that the study of tracks of galactic cosmic rays in olivine crystals from meteorites opens new capabilities for the investigation of fluxes and spectra in cosmic rays in the region of heavy and superheavy nuclei.

The results are presented of model calculation of the interaction and yield of galactic-cosmic-ray superheavy-element nuclear fragmentation products from the 50 < Z < 92 range of their charges as they pass through a certain meteorite-pallasite substance thickness.

This paper presents the results of the mineralogical, petrographic, elemental, and isotopic analysis of the Chelyabinsk meteorite and their geochemical interpretation. It was shown that the meteorite can be assigned to LL5-group ordinary chondrites and underwent moderate shock metamorphism (stage S4). The Chelyabinsk meteorite contains a significant fraction (approximately one-third by volume) of shock-melted material similar in composition to the main volume of the meteorite. The results of isotopic analysis suggest that the history of meteorite formation included an impact event approximately 290 Ma ago.

Thermoluminescence, noble gases, and the tracks of iron-group elements and cosmogenic radionuclides of various half-lives were examined in the fresh-fallen Ash Creek (L6) and Tamdakht (H5) chondrites. The experimental information thus obtained and theoretical simulations were used to study the shock-thermal and exposure histories of the chondrites, to evaluate their preatmospheric sizes and masses, values of ablation, the sizes of their orbits, and to monitor the distribution and variations in cosmic radiation in the heliosphere during the transitional period of minimum between solar cycles 23 and 24.

Citation: Bagulya, A. V., L. A. Goncharova, A. I. Ivliev, G. V. Kalinina, L. L. Kashkarov, N. S. Konovalova, N. M. Okateva, N. G. Polukhina, A. S. Roussetski, N. I. Starkov (2012), Fragmentation of the uranium nuclei in ironnickel pallasite medium: theoretical estimation of the fragment nuclei superposition with the primary galactic cosmic ray nuclus abundance, Vestn. Otd. nauk Zemle, 4, NZ9001, doi:10.2205/2012NZ_ASEMPG

The registration parameters of a new plastic track detector (PTD) for nuclear particles have been experimentally investigated. The PTD is a modification of a CR-39 detector and is labeled CZ. As compared to the CR-39 detector with a similar chemical composition, the CZ PTD produced by the Semenov Institute of Chemical Physics from allyl diglycol carbonate (C12H18O7) has a considerably higher sensitivity and better dynamical (the track etching rate and the rate of etch removal of a substance from the surface of a PTD plate) and geometrical (etchable track length and diameter) registration parameters. Based on results of the calibration experiments with α particles of different energies, fission fragments of 252Cf, and accelerated 20Ne ions, the theoretical estimate was obtained for the threshold value of the specific ionization losses, the sensitivity, and the detection efficiency for nuclear particles, beginning with protons.

The content of cosmogenic radionuclides, in particular, 60Co and 26Al, as well as VH-nucleus track density in the fresh-fallen Kilabo LL6-chondrite are measured. The obtained results and the available data of [5] on the content of 26Al and noble gases in the fresh-fallen Bensour LL6-chondrite are used with earlier developed methods for determination of the pre-atmospheric sizes and orbits of these chondrites. The closeness of orbits of the Kilabo and Bensour chondrites, the striking likeness of their composition, structure and petrography allow us to suppose their origin from a single source; at the same time the resemblance of the reflection spectra of the LL6-chondrites with that of the main belt 3628 Boznemcova asteroid allow us to consider it as the parent body of the LL6-chondrites. On the strength of all the evidence, the following scenario is suggested: (1) knocking out of both the chondrites from the 3628 Boznemcova asteroid at a distance ∼2.2 AU from the Sun about 19 million years ago, the Bensour chondrite being knocked out from deeper layers of the parent asteroid, which were completely shielded from cosmic rays, while the material of the Kilabo chondrite being probably irradiated by cosmic rays on the asteroid surface for 14 million years before its knock-out; (2) the drift of the chondrites due to the Yarkovsky effect into the region of secular resonance g=g6, which was accompanied by variation of the semimajor axis a by ∼0.05 AU over ∼18 million years; (3) the resonance transfer of the Kilabo and Bensour chondrites to their present orbits over the last ∼1 million years.

Pallasites are specific stony-iron class of meteorites are mixtures of olivine and Fe-Ni. Olivine is one of the suitable silicate mineral for registration heavy cosmic ray nuclei with help of chemically etched tracks. Five meteorites of this class were selected for study by the track and thermoluminescence (TL) methods: Brenham, Eagle Station, Ilimaes, Marjalahti and Omolon. For measurement of the natural and artificially induced TL it was used high-sensitive TL equipment. The significant difference of the typical glow-curve shapes between pallasites under investigation was determined. The total difference was observed in comparison with TL glow-curves, measured in artificially shocked olivine samples. Note that our TL observations indicate on chief connection with the olivine crystal microstructure and the very low level of possible shock influence recorded in all analysed olivine crystal samples. It was obtained that the shape of the track-density distribution, observed in the Brenham olivine crystals, supports assumption, that this distribution resembles determined irradiated on pre-compaction stage crystals, when the predominant part of tracks represent an addition from the solar cosmic ray VH-nuclei.

In this work performed in frame to OLIMPIYA project [5] there are presented new results of measurement of fluxes and of the spectra of superheavy nuclei composing cosmic rays. The method of detection and analysis of nucleus tracks found in the olivine crystals of meteorites was used. The experiment is based on the combined method including the multistage meteorite etching and nucleus track registration and measurement on completely automated PAVICOM setup [5]. The track parameters such as diameter, length and the etching velocity are investigated. On the first stage of the experiment there was held the calibration procedure for nuclei charge identification using the accelerated nuclei Xe and U. The etching length of nuclei (26