VK Utyonkov's research while affiliated with Joint Institute for Nuclear Research and other places

Publications (23)

Article
Full-text available
Forsberg and Leino (2019 J. Phys. G: Nucl Part Phys 46 018001) question the validity of criticism (2017 J. Phys. G: Nucl. Part. Phys. 44 075107) of the method proposed by Forsberg et al (2016 Nucl. Phys. A 953 117). In this reply, we show that this method is based on unclear principles and its implementation leads to the results that contradict the...
Article
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The synthesis of superheavy elements asks for the analysis of low statistics experimental data presumably obeying an unknown exponential distribution and to take the decision whether they originate from one source or have admixtures. Here we analyze predictions following from non-parametrical methods, employing only such fundamental sample properti...
Article
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Gas-phase chromatography studies of nihonium (Nh, Z=113) were carried out at the one-atom-at-a-time level. For the production of nihonium, the heavy-ion-induced nuclear fusion reaction of 48Ca with 243Am was used. This leads to isotopes 284,285Nh, as the direct descendants of the alpha-decaying precursors 288,289Mc. Combining the Dubna Gas-Filled R...
Article
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The analysis of decay chains starting at superheavy nuclei ²⁹³Ts and ²⁸⁹Mc is presented. The spectroscopic properties of nuclei identified during the experiments using the ²⁴⁹Bk+⁴⁸Ca and ²⁴³Am+⁴⁸Ca reactions studied at the gas-filled separators DGFRS, TASCA and BGS are considered. We present the analysis of decay data using widely adopted statistic...
Article
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Discovery and investigation of the “Island of stability” of superheavy nuclei at the separator DGFRS in the 238U-249Cf+ 48Ca reactions is reviewed. The results are compared with the data obtained in chemistry experiments and at the separators SHIP, BGS, TASCA, and GARIS. The synthesis of the heaviest nuclei, their decay properties, and methods of i...
Article
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The actinide resources and production capabilities at Oak Ridge National Laboratory (ORNL) are reviewed, including potential electromagnetic separation of rare radioactive materials. The first experiments at the Dubna Gas Filled Recoil Separator (DGFRS) with a new digital detection system developed at ORNL and University of Tennessee Knoxville (UTK...
Article
Slowing down and stopping of the heaviest atoms, products of the fusion-evaporation nuclear reactions, during their passage through the Dubna gas-filled recoil separator has been studied using TRIM simulations. The study is important for experiments on the synthesis of super-heavy elements (SHEs) with atomic numbers around ZP = 114 produced with ac...
Article
Full-text available
The discovery and investigation of the new region of superheavy nuclei at the DGFRS separator based on fusion reactions of 48Ca with 238U–249Cf target nuclei are reviewed. The production cross sections and summaries of the decay properties, including the results of the posterior experiments performed at the SHIP, BGS, and TASCA separators, as well...
Article
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A review of the discovery and investigation of the 'island of stability' of super-heavy nuclei at the separator DGFRS (FLNR, JINR) in the fusion reactions of (48)Ca projectiles with target nuclei (238)U-(249)Cf is presented. The synthesis of the heaviest nuclei, their decay properties, and methods of identification are discussed. The role of shell...
Conference Paper
Full-text available
The discovery of new higher Z elements and the determination of their decay properties provide important insights into our understandings of the behaviour of nuclear matter under extreme conditions of high Z and important tests of the prediction of an island of stability around N=184 and high Z (114 or even 120-126). The synthesis of odd-Z superhea...
Article
Calibration is the transformation of the output channels of a measuring device into the physical values (energies, times, angles, etc.). If dealt with manually, it is a labor- and time-consuming procedure even if only a few detectors are used. However, the situation changes appreciably if a calibration of multi-detector systems is required, where t...
Article
Discovery of two isotopes of the new element 117 in the Bk-249 + Ca-48 reaction is described. A new Am-243 + Ca-48 experiment was carried out to firmly establish the discoveries of new elements 115 and 113. A total of thirty one decay chains of (288)115 are now observed in the Am reaction. In addition, four new decay chains are assigned to (289)115...
Conference Paper
This paper presents results of experiments aimed at producing long-lived superheavy elements located near the spherical shell closures with Z>=114 and N>=172 in the reactions of neutron-rich isotopes 244Pu, 248Cm and 249Cf with 48Ca projectiles. The decay properties of the synthesized nuclei are consistent with the consecutive alpha-decays originat...
Conference Paper
This paper presents results of experiments aimed at producing long-lived superheavy elements located near the spherical shell closures with Z ≥114 and N ≥172 in the reactions of neutron-rich isotopes 244Pu, 245,248Cm and 249Cf with 48Ca projectiles. The decay properties of the synthesized nuclei are consistent with the consecutive α-decays originat...
Article
In this paper, we present the Monte Carlo Random Probability (MCRP) calculational method details that were developed for the determination of random correlations in a set of unrelated data. After finding random correlations, we further process the correlations by applying nuclear property systematics. We compare the results of MCRP with methods pre...
Article
Full-text available
This paper presents results of the experiments aimed at producing long-lived superheavy elements located near the spherical shell closures with Z >= 114 and N >= 172. For the synthesis of superheavy nuclei, we used a combination of neutron-rich reaction partners, with a 244Pu target and a 48Ca projectile. The sensitivity of the present experiment e...
Article
The first results of experiments on the synthesis of superheavy nuclei, for which the modern nuclear theory predicts significant increase in stability, are presented. In a 34-day bombardment of a Pu-244 target with 5.2 x 10(18) Ca-48 ions using the Dubna Gas-filled Recoil Separator we observed a decay sequence consisting of an implanted heavy atom,...

Citations

... The gas chromatography studies of the Nh (Z = 113) isotopes obtained at RIKEN allowed to suggest the 6d 10 7s 2 7p 1 1/2 configuration and, therefore, the belonging of Nh to 13-group, but prevented an unambiguous chemical speciation of the element (Türler et al. 2015). More information on the chemistry of Nh was obtained later by the Dubna team, that performed adsorption experiments after a physical preparation of Nh samples (Aksenov et al. 2017), finding agreement with the Nh gas-phase behavior predicted by relativistic density functional theory. However, as recently pointed out by Eichler (2019a), a definitive chemical characterization of Nh has not yet been reached. ...
... Using this method, it is seen that the set of fourteen 'short' α-decay chains observed in the reaction 48 Ca+ 243 Am are unlikely to have a common origin. This is not contradictory to the calculations by Zlokazov and Utyonkov [2], which show that if each decay step is considered separately there is no strong reason for questioning the congruence of the data set including both these fourteen short chains and decay chains assigned to start from the isotope 293 117. If the methods used by Zlokazov and Utyonkov were applied to the same data set as was considered in [1], the result would be that there is no strong reason to question the congruence of the fourteen short chains. ...
... To find the optimal production methods, systematic fusion reaction studies are being carried out (Itkis et al., 2015;Loveland, 2016;Hinde et al., 2017;Khuyagbaatar et al., 2018). One proposed route involves an enriched 251 Cf target and 58 Fe beam (Rykaczewski et al., 2016). Reactions using multinucleon transfer and radioactive neutron-rich beams are also being considered (Loveland, 2007;Zagrebaev and Greiner, 2008;Schädel, 2016;Karpov, Rachkov, and Saiko, 2018). ...
... The half-lives of the stable isotopes of these elements can be from several minutes to several years (up to thousands of years, according to over-optimistic estimates [5]). Attempts to produce new superheavy elements and to synthesize elements with Z ≥ 100 continue on accelerators [6][7][8]. ...
... As the data in [16] reach only up to uranium (Z = 92), we explored ways how to extrapolate stopping powers from uranium up to fermium (Z = 100). Extrapolations to superheavy elements were recently done by Wittwer et al. [17] and by Sagaidak et al. [29] using the proportionality of the stopping force STF of the heavy ion to the square of the effective charge and the equivalent proton-STF (same energy per nucleon), STF eq.Z=1 ...
... In experiments carried out over the past 20 years, the theory pointing to the existence of a region of superheavy elements (SHE) has received experimental confirmation. In complete-fusion reactions of 48 Ca with actinide (Act) targets the heaviest isotopes of Nh (Z = 113) and five new elements from Fl (Z = 114) 5 to Og (Z = 118) were synthesized and the decay properties of more than 50 new heaviest isotopes of elements from Rf to Og have been studied [1,2]. The gas-filled separator DGFRS (further we will call it DGFRS-1), installed at the U400 cyclotron of FLNR in 1989 was used in these experiments. ...
... The study on the superheavy elements (SHEs) is one of the most important topics in nuclear physics nowadays [1][2][3][4]. The cross section of fusion-evaporation reactions for producing superheavy nuclei (SHN) is extremely small, in the order of 10 −36 cm 2 and strongly dependent on the combination of two colliding nuclei and the incident energy. ...
... τ is fulfilled and there are no sharp jumps in its structural evolution. In the SPEVA (SPectra EVolution Analysis) package, the algorithm for automatically analyzing the sequence of spectra takes existing a priori information into account and executes several routine operations: autoindexing[5,6], i.e., the search for peaks, the transfer of their positions to interplanar distances (d hkl ), and determination of the initial parameters of the unit cells of the given phases; determination of the positions and the integral intensities of the found peaks and determination of more precise values of certain parameters on their basis by minimizing the corresponding functional (this mode will be denoted as the UPEAK-mode below); description of the total diffraction pattern profile for determination of the structure characteristic of individual phases (the set of parameters P ik ) and the coefficients A ik (it is denoted as the Rietveld-mode below). We consider some specific features of the applied algorithms. ...
... Hitherto, many SHN up to Z = 118 have been observed despite of their extremely small cross sections (few pb) [26][27][28][29][30][31]. The development of advanced experimental techniques, together with the observation of 294 Og (Z = 118) isotope, has encouraged fusioneers to go further toward the northern island of stability for new superheavy elements [32]. ...
... This method was applied to the data on the synthesis of the 114 th element. It is named flevorium after (Stoyer et al., 2000). All signals were recorded in the same strip detector. ...