G. V. Kalinina

“Hot” particles in soil from chernobyl AES region

Abstract The measuring of the α-activity and sizes of the “hot” particles from the Chernobyl AES by means of the CZ-type solid state nuclear track detector (SSNTD) has been performed.

CHARGE SPECTRUM OF HEAVY AND SUPERHEAVY COMPONENTS OF GALACTIC COSMIC RAYS: RESULTS OF THE OLIMPIYA EXPERIMENT

The aim of the OLIMPIYA experiment is to search for and identify traces of heavy and superheavy nuclei of galactic cosmic rays (GCR) in olivine crystals from stony–iron meteorites serving as nuclear track detectors. The method is based on layer-by-layer grinding and etching of particle tracks in these crystals. Unlike the techniques of other authors, this annealing-free method uses two parameters: the etching rate along the track (V etch) and the total track length (L), to identify charge Z of a projectile. A series of irradiations with different swift heavy ions at the accelerator facilities of GSI (Darmstadt) and IMP (Lanzhou) were performed in order to determine and calibrate the dependence of projectile charge on V etch and L. To date, one of the most essential results of the experiment is the obtained charge spectrum of GCR nuclei within the range of Z > 40, based on about 11.6 thousand processed tracks. As the result of data processing, 384 nuclei with charges Z ≥ 75 have been identified, including 10 nuclei identified as actinides (90 < Z < 103). Three tracks were identified to be produced by nuclei with charges 113 < Z < 129. Such nuclei may be part of the Island of Stability of transfermium elements.

Detecting galactic cosmic ray transuranium nuclei in olivine crystals from meteorites

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.

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.

Charge spectrum of superheavy nuclei of galactic cosmic rays obtained in the OLIMPIA experiment

In this paper, we present the last results of the OLIMPIA experiment on the search for and study of traces of heavy and superheavy element nuclei of galactic cosmic rays in olivine crystals from meteorites. The charge spectrum of cosmic rays in the region of heavy nuclei is obtained, three superheavy nuclei of natural origin with charges in the range 105 < Z < 130 and lifetimes longer than 3000 years, being a part of the so-called “stability island”, are identified.

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 the “stability island” of superheavy nuclei using natural track detectors

The method of using natural track detectors, i.e., meteorite olivine crystals, is developed and improved applied to the problem of searching for superheavy nuclei in nature, in galactic cosmic rays (GCR). The new technique implements the sequence of etching, grinding, and track identification operations using the automated PAVICOM facility. The data on the track length and etching rate in combination with the results of calibration on heavy nucleus accelerators allowed the development of a technique for determining the GCR nucleus charge with an accuracy of ±2. On this basis, a significant set of experimental data on superheavy nuclei of natural origin was obtained (21743GCRheavy nucleiwithZ >20, including three nucleiwith a charge of 119−6+10). The minimum lifetime Tmin of the last-mentioned is within 50 years< Tmin < 100 years, which exceeds the lifetime of transfermium nuclei synthesized on accelerators by many orders of magnitude. The long-lived superheavy nuclei detected in the GCR spectrum can belong to the “stability island”.

Charge distribution of superheavy elements in galactic cosmic rays on base of investigations in olivine crystals from meteorites

An original method of studying chemically etched tracks of heavy nuclei in olivine from pallasite meteorites was used to obtain a charge distribution of approximately 9000 nuclei with charges above 55 in galactic cosmic rays. Three superheavy nuclei with the charges in the range of 105<Z<130 were detected. Regression analysis enabled to amend the charge of one of these nuclei up to the value 119−6+10 with the probability of 95%. Such nuclei have to form islands of stability of superheavy elements; their occurrence in nature supports the validity of theoretical predictions and justifies efforts for their synthesis under the Earth conditions.

Simulation of Passage of Gallactic Cosmic Ray Nuclei in Meteorite-Pallasite Substance

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.

Study of the charge distribution of galactic cosmic rays and search for superheavy nuclei traces in olivine crystals from meteorites

The search for and identification of energetic nuclei of superheavy elements of cosmic rays in olivine crystals frommeteorites, currently performedwithin the Olympia project [1], are based on measurements of dynamic and geometrical parameters of tracks, i.e., chemically etchable regions of the traces of slowing down of these nuclei before their stop, using the fully automated PAVIKOM measuring system [2].