Yu. S. Tsyganov

Joint Institute for Nuclear Research, Dubno, MO, Russia

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Publications (85)149.35 Total impact

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    ABSTRACT: Irradiations of Pu239 and Pu240 targets with Ca48 beams aimed at the synthesis of Z=114 flerovium isotopes were performed at the Dubna Gas Filled Recoil Separator. A new spontaneously fissioning (SF) isotope Fl284 was produced for the first time in the Pu240+Ca48 (250 MeV) and Pu239+Ca48 (245 MeV) reactions. The cross section of the Pu239(Ca48,3n)Fl284 reaction channel was about 20 times lower than predicted by theoretical models and about 50 times lower than the maximum fusion-evaporation cross section for the 3n and 4n channels measured in the Pu244+Ca48 reaction. In the Pu240+Ca48 experiment, performed at 245 MeV in order to maximize the 3n-evaporation channel, three decay chains of Fl285 were detected. The α-decay energy of Fl285 was measured for the first time and decay properties of its descendants Cn281, Ds277, Hs273, Sg269, and Rf265 were determined with higher accuracy. The assignment of SF events observed during the irradiation of the Pu240 target with a 250 MeV Ca48 beam to Fl284 decay is presented and discussed. The cross sections at both Ca48 energies are similar and exceed that observed in the reaction with the lighter isotope Pu239 by a factor of 10. The decay properties of the synthesized nuclei and their production cross sections indicate a rapid decrease of stability of superheavy nuclei as the neutron number decreases from the predicted magic neutron number N=184. © 2015 American Physical Society.
    Full-text · Article · Sep 2015 · Physical Review C
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    Yu. S. Tsyganov
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    ABSTRACT: A new approach to provide a fruitful analysis of signal amplitude is proposed. It is this method that has made it possible to eliminate some observed artificial events from the list of candidates for decays of superheavy nuclei. Examples of estimates of measured amplitudes of evaporation residues (EVR) are presented. Some attention is paid to a new hard statistical criterion for detecting rare events. This criterion can be applied in the case of significant role of random factors.
    Preview · Article · Jun 2015 · Physics of Particles and Nuclei Letters
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    Yu. S. Tsyganov · A. M. Sukhov · A. N. Polyakov
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    ABSTRACT: Two decay chains originated from the even-even isotope 294118 produced in the 3n-evaporation channel of the 249Cf+48Ca reaction. Method of active correlations is applied to suppress backgrounds associated with the cyclotron. It is planned to apply this technique for the forthcoming experiment aimed to the synthesis of Z=120 element. A calibration dependence for a recoil measured energy signal is presented as well as a computer simulation spectrum for Z=118 nuclei.
    Preview · Article · Jun 2015
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    Yu. S. Tsyganov
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    ABSTRACT: A new real-time PC based algorithm and a compact C++ code to operate in a real-time mode with a 48x128 strip double side position sensitive large area silicon radiation detector Micron Semiconductors (UK) are developed and tested. Namely with this new approach it has become possible to provide the quick extraction of EVR-alpha correlated sequences in heavy ion induced complete fusion nuclear reactions. Specific attention is paid to the application of new CAMAC 4 M modules for charge particle position measurement during long- term experiments aimed to the synthesis of new superheavy nuclei. Some attention is paid to the different (combined) algorithm scenario to search for ER-alpha and alpha-alpha chains.
    Preview · Article · Jun 2015 · Physics of Particles and Nuclei Letters
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    Yu. S. Tsyganov
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    ABSTRACT: Real-time PC based algorithm is developed for DSSSD ( Double Side Silicon Strip Detector) detector. Brief description of the detection system is also presented. Complete fusion nuclear reaction natYb+48Ca->217Th is used to test this algorithm at 48Ca beam. Example of successful application of a former algorithm for resistive strip PIPS detector is presented too.
    Preview · Article · Jun 2015 · Physics of Particles and Nuclei Letters
  • Yu. S. Tsyganov
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    ABSTRACT: An application developed in Builder C++ (Windows) for the offline analysis of experimental data from the spectrometer of the gas-filled separator of recoil nuclei (Flerov Laboratory of Nuclear Reactions) based on the double-sided silicon strip detector is discussed. The automatic express method developed for calibrating 48 strips of the silicon position-sensitive detector based on the three most energetic spectral lines from the natYb + 48Ca▭*Th reaction is compared to the results produced by more rigorous calibration methods. The examples of spectra for this reaction and the results of filtering for the proposed calibration algorithm are given.
    No preview · Article · Mar 2015 · Physics of Particles and Nuclei Letters
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    ABSTRACT: The reaction of 249Bk with 48Ca has been investigated with an aim of synthesizing and studying the decay properties of isotopes of the new element 117. The experiments were performed at five projectile energies (in two runs, in 2009-2010 and 2012) and with a total beam dose of 48Ca ions of about 9x1019 The experiments yielded data on a-decay characteristics and excitation functions of the produced nuclei that establish these to be 293117 and 294117-the products of the 4n- and 3n-evaporation channels, respectively. In total, we have observed 20 decay chains of Z=117 nuclides. The cross sections were measured to be 1.1 pb for the 3n and 2.4 pb for the 4n-reaction channel. The new 289115 events, populated by α decay of 117, demonstrate the same decay properties as those observed for 115 produced in the 243Am(48Ca,2n) reaction thus providing cross-bombardment evidence. In addition, a single decay of 294118 was observed from the reaction with 249Cf-a result of the in-growth of 249Cf in the 249Bk target. The observed decay chain of 294118 is in good agreement with decay properties obtained in 2002-2005 in the experiments with the reaction 249Cf(48Ca,3n)294118. The energies and half-lives of the odd-Z isotopes observed in the 117 decay chains together with the results obtained for lower-Z superheavy nuclei demonstrate enhancement of nuclear stability with increasing neutron number towards the predicted new magic number N=184.
    Full-text · Article · Feb 2015 · Journal of Physics Conference Series
  • Yu. S. Tsyganov
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    ABSTRACT: Schematics, software products, and their realization in a Builder C++ environment for experiments on the synthesis of superheavy elements on a Dubna gas-filled recoil nuclei separator (DGFNS) plant at the Flerov Laboratory of Nuclear Reactions (FLNR) of the Joint Institute for Nuclear Research (JINR) are considered. Examples of application in complete fusion reactions with 48Ca ions are given.
    No preview · Article · Jan 2015 · Physics of Particles and Nuclei Letters
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    ABSTRACT: The reaction of Bk-249 with Ca-48 have been reinvestigated to provide new evidence for the discovery of element 117 on a larger number of events. The experiments were performed at five projectile energies and with a total beam dose of Ca-48 of about 4.6x10(19). Two isotopes (293,294)117 were synthesized in the Bk-249+Ca-48 reaction, providing excitation functions and alpha-decay spectra of the produced isotopes that establishes these nuclei to be the products of the 4n- and 3n-evaporation channels, respectively. Decay properties of (293,294)117 and of all the daughter products agree with the data of the experiment in which these nuclei were synthesized for the first time in 2010. The new (289)115 events, populated by alpha decay of (293)117, demonstrate the same decay properties as those observed for (289)115 produced in the Am-243(Ca-48, 2n) reaction thus providing cross-bombardment evidence. In addition, a single decay of (294)118 was observed from the reaction with Cf-249 - a result of the in-growth of Cf-249 in the Bk-249 target.
    Full-text · Article · Jan 2014 · The European Physical Journal Conferences
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    ABSTRACT: Studies of superheavy nuclei produced in the 249Bk + 48Ca reaction were performed using the Dubna Gas Filled Recoil Separator. The cross section for the production of 293117 and 294117 isotopes was measured at five excitation energies of the 297117 compound nucleus ranging from 30 to 48 MeV and yielding maximum values of 1.1+1.2 −0.6 pb for the 3n and 2.4+3.3 −1.4 pb for the 4n reaction channels. Alpha emission from 281Rg competing with spontaneous fission (α/SF decay probability 1:9) was observed for the first time leading to the identification of the new isotope 277Mt (TSF ≈ 5 ms). The measured decay properties are in good agreement with those expected based on the properties of neighboring even-Z and odd-Z nuclei. The α energies and half-lives of odd-Z isotopes observed in the 293117 and 294117 decay chains together with results obtained for lower-Z superheavy nuclei demonstrate enhanced stability with increasing neutron number toward the predicted new magic number N = 184.
    Full-text · Article · May 2013 · Physical Review C
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    ABSTRACT: Production and decay of the isotopes of Hs were studied in the 226Ra+48Ca reaction at beam energies Elab=229, 234, and 241 MeV. At the Elab=234 MeV energy, the maximum of the 4n-evaporation channel of the reaction, six identical α-SF decay chains of the nucleus 270Hs were detected corresponding to a cross section of σ4n=16−7+13 pb. At the other 48Ca energies, no Hs isotopes were observed. Nuclei of 270Hs undergo α decay with a Qα=9.15±0.08 MeV and the half-life of the daughter spontaneous fission (SF) isotope 266Sg is 0.28−0.08+0.19 s, in good agreement with the data previously observed in the 248Cm(26Mg,4n)270Hs reaction. The partial α-decay half-life of 270Hs was measured for the first time: Tα=7.6−2.2+4.9 s. For the spontaneous fission, we determined a lower limit TSF⩾10 s. Decay properties of 270Hs corroborate theoretical predictions of its relatively high stability caused by the effect of the deformed shells at Z=108 and N=162.
    Full-text · Article · Mar 2013 · Physical Review C
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    ABSTRACT: The reaction 243Am + 48Ca has been reinvestigated to provide new evidence for the discovery of elements 113, 115. Twenty eight new 288115 decay chains were detected in this reaction to increase from three to 31 the number of 288115 atoms observed. In addition, four new decay chains were observed for the first time and assigned to the decay of 289115. These new 289115 events have the same properties for their decay chains as those observed for 289115 populated in the alpha decay of 293117 produced in the 249Bk + 48Ca reaction to provide cross-bombardment evidence. These new high statistics data sets and the cross-bombardment agreement provide definitive evidence for the discoveries of the new elements with Z = 113, 115, 117.
    Full-text · Article · Mar 2013 · Journal of Physics Conference Series
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    V.B. Zlokazov · V.K. Utyonkov · Yu.S. Tsyganov
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    ABSTRACT: 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 the number of registering devices extends to hundreds (Tsyganov et al. (2004) [1]). The calibration is aggravated by the fact that needed pivotal channel numbers should be determined from peak-like distributions. But peak distribution is an informal pattern so that a procedure of pattern recognition should be employed to discard the operator interference. The automatic calibration is the determination of the calibration curve parameters on the basis of reference quantity list and the data which partially are characterized by these quantities (energies, angles, etc). The program allows the physicist to perform the calibration of the spectrometric detectors for both the cases: that of one tract and that of many.
    Full-text · Article · Feb 2013 · Computer Physics Communications
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    ABSTRACT: Results from the production and decay properties of element 115 nuclei observed using the reaction 243Am + 48Ca at various beam energies between November 1, 2010, and February 26, 2012, at the Dubna Gas Filled Recoil Separator are presented. This long-running experiment with a total beam dose of 3.3 × 1019 and carried out in the excitation energy range E ∗ = 31–47 MeV of the 291115 compound nucleus resulted in observation of three isotopes of element 115 with masses 287, 288, and 289. The 28 detected decay chains of 288115 show that this isotope is produced with the maximum probability at E ∗ = 34.0–38.3 MeV with a corresponding cross section of σ3n = 8.5+6.4 −3.7 pb. The four events attributed to the isotope 289115 that decays via a short α → α → SF chain could be detected only at the lowest excitation energy E ∗ = 31–36 MeV, in accordance with what could be expected for the 2n-evaporation channel of the reaction. The decay characteristics of this nuclide were established earlier (2010) and more recently (2012) in the reaction 249Bk(48Ca,4n)293117 and following α decay to 289115. At the energy E ∗ = 44.8 ± 2.3 MeV we observed only a single long chain of the isotope 287115. The decay properties of nuclei starting at 288115 and 287115 isotopes obtained in the present work reproduce in full the results of the first experiment of 2003 that reported the discovery of elements 115 and 113. The excitation functions of the production of the isotopes of element 115 and observation of the isotope 289115 in cross-bombardment reactions with the targets of 243Am and 249Bk provide additional evidence of the identification of the nuclei of elements 115 and 113. The experiments were carried out using the 48Ca beam of the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions, JINR.
    Full-text · Article · Jan 2013 · Physical Review C
  • Y.S. Tsyganov · A.N. Polyakov · A.M. Sukhov
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    ABSTRACT: New detection system of the Dubna Gas Filled Recoil Separator [1 - 3] (DGFRS) was put into operation in May 2012. It includes 32-strip position sensitive PIPS detector manufactured by CANBERRA NV, 24-strip back side PIPS detector, 8-strip "VETO" PIPS detector, time-of-flight low pressure (~1.7 Torr) pentane-filled gaseous detector, CAMAC fast ADC's with 5 μs dead time per three signals (energy, top position, bottom position), modified CC012 crate controller and PC-based C++ Builder code for spectrometry data acquisition. New parameter monitoring system (project) is reported too together with the brief review of the present system. It is planned to put into operation with this system during 2013-2014. Examples of applications in the long-term experiments aimed at the synthesis of superheavy elements in 48Ca induced complete fusion nuclear reactions are also presented. Namely with the DGFRS facility 45 new isotopes of superheavy nuclei were synthesized since 2001.
    No preview · Article · Jan 2013
  • Yu. S. Tsyganov
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    ABSTRACT: As far as the detection system is concerned, experimens on synthesis and study of the properties of superheavy nuclei is one of the most difficult tasks. In fact, these experiments can be considered extreme in many senses: —extremely low (fractions of a picobarn-picobarns) formation cross sections of the products under investigation —extremely high heavy ion beam intensities for example, ∼1.1–1.5 pμA1 48Ca —high radioactivity of actinide targets, which are used in the experiments aimed at the synthesis of super-heavy nuclei —very long duration of the experiment (as long as a year) —extremely low yield of the products under investigation (sometimes less than 1 per month) —very high sensitivity of the detection system —radical suppression of the background products (method of “active correlations”). The two last points are the subject of the present paper, as well as the subject of two of my reviews published before. It is evident that without knowledge of the nature of the internal processes in semiconductor detectors it is virtually impossible to provide clear detection of ultra rare signals. In the present paper, the author reports on the investigation of near-surface phenomena in silicon radiation detectors, first of all bearing in mind the theoretical-methodological aspect of these phenomena. Non-equilibrium electron-hole recombination, pulse height defect formation, charge multiplication, and formation of “hot” electron system, are considered. With just these phenomena one can observe nonlinearity of energy-charge-amplitude conversion for heavy ion (recoil nucleus) registered by a silicon detector. Practical applications are also considered. One of them is a deeply modified method of “active correlations”. Projection of applying the method in the experiments with the modernized cyclotron (DC-280 FLNR project) is projected as well as possible applications in the heavy-ion-induced complete fusion nuclear reactions.
    No preview · Article · Jan 2013 · Physics of Particles and Nuclei
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    ABSTRACT: Two years after the discovery of element 117, we undertook a second campaign using the ^{249}Bk+^{48}Ca reaction for further investigations of the production and decay properties of the isotopes of element 117 on a larger number of events. The experiments were started in the end of April 2012 and are still under way. This Letter presents the results obtained in 1200 hours of an experimental run with the beam dose of ^{48}Ca of about 1.5×10^{19} particles. The ^{249}Bk target was irradiated at two energies of ^{48}Ca that correspond to the maximum probability of the reaction channels with evaporation of three and four neutrons from the excited ^{297}117. In this experiment, two decay chains of ^{294}117 (3n) and five decay chains of ^{293}117 (4n) were detected. In the course of the long-term work, ^{249}Cf-the product of decay of ^{249}Bk (330 d)-is being accumulated in the target. Consequently, in the present experiment, we also detected a single decay of the known isotope ^{294}118 that was produced during 2002-2005 in the reaction ^{249}Cf(^{48}Ca,3n)^{294}118. The obtained results are compared with the data from previous experiments. The experiments are carried out in the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, using the heavy-ion cyclotron U400.
    Full-text · Article · Oct 2012 · Physical Review Letters
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    ABSTRACT: Results of a new series of experiments on the study of production cross sections and decay properties of the isotopes of element 115 in the reaction (243)Am+(48)Ca are presented. Twenty-one new decay chains originating from (288)115 were established as the product of the 3n-evaporation channel by measuring the excitation function at three excitation energies of the compound nucleus (291)115. The decay properties of all newly observed nuclei are in full agreement with those we measured in 2003. At the lowest excitation energy E*=33 MeV, for the first time we registered the product of the 2n-evaporation channel, (289)115, which was also observed previously in the reaction (249)Bk+(48)Ca as the daughter nucleus of the decay of (293)117. The maximum cross section for the production of (288)115 is found to be 8.5 pb at E*≈36 MeV.
    No preview · Article · Jan 2012 · Physical Review Letters
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    ABSTRACT: No abstract prepared.
    Full-text · Article · Dec 2011
  • Yu. S. Tsyganov
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    ABSTRACT: Experiments carried out on the gas-filled separator of recoil nuclei at the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, in the past several years have proved the hypothesis of the existence of a stability island of superheavy nuclei. The accelerator, beam diagnostics, and detector technologies underlay the success. It is the highly sensitive detecting system of the separator combined with the method of “active correlations” that allowed rare events of the decay of superheavy nuclei to be reliably detected under almost background-free conditions. In turn, to a large extent, this has been made possible owing to special algorithms and software developed for long-term experiments in the beam of 48Ca ions.
    No preview · Article · Sep 2011 · Physics of Particles and Nuclei