The article presents working results of radiation status survey in the territory adjacent to the “Atomic lake”, a venue of the ﬁrst USSR excavation explosion. In the course of research, a picture of areal radiation contamination has been obtained in the territory with technogenic radionuclides 137Cs, 241Am, 152Eu. A pattern of radionuclide distribution in depth is shown at different spots (crater bank, Shagan river ﬂoodplain, the area of the external reservoir). Data is presented on concentrations of technogenic radionuclides 3H, 239+240,238Pu, 90Sr, 60Co, 154Eu, 152Eu in soil.
This work is an attempt to present some problems on the evolution of the Universe: the nucleosynthesis and cosmochronology from the standpoint of physics of particles and nuclei, in particular with the use of the lat est results, obtained by means of radioactive nuclear beams. The comparison is made between the processes taking place in the Universe and the mechanisms of for mation and decay of nuclei, as well as of their interaction at different energies. Examples are given to show the capabilities of nuclear physics methods for studying cosmic objects and properties of the Universe. The results of investigations in nuclear reactions, induced by radioactive nuclear beams, make it possible to analyze the nucleosynthesis scenario in the region of light elements in a new manner.
The results of studies of the ionic conductivity and the conjugated chemical diffusion coefﬁcients (CCDC) in the nonstoichiometric LixCu1.75Se (0≤x≤0.25) ternary alloys are presented. It has been observed that the values of the ionic conductivity of Cu1.75Se copper selenide decreases with lithium doping in general owing to increasing the the activation energy. The increasing of the conjugate chemical diffusion coefﬁcients of the cations and electron holes was observed with increasing of lithium content, despite the decreasing of self-diffusion coefﬁcients of the cations and decreasing of electron mobilities. The behavior of the conjugate chemical diffusion coefﬁcients explained by a decrease in the degree of non-stoichiometry of the composition, leading to an increase of the internal electric ﬁeld accelerating the motion of slower particles.
Angular distributions of protons, deuterons, tritons and alpha particles emitted in the reaction 2H+9Be at Elab =19.5 MeV were measured with an aim to shed light on the internal cluster structure of 9Be and to study possible cluster transfer of 5He. The analyses suggest a signiﬁcant contribution of ﬁve-nucleon transfer in the reaction channel 9Be(d,4He )7Li.
Authors: A. Yeremin, A. Popeko, O. Malyshev, V. Chepigin, A. Svirikhin, A. Isaev, Yu. Popov, M. Chelnokov, A.Karpov,
A. Kuznetsova, I. Izosimov, E. Sokol, V. Saiko, D. Katrasev, A. Lopes-Martens, K. Hauschild, K.Rezynkina,
O.Dorvaux, B. Gall, Z. Asfari, P. Brionett, J. Piot, S. Hofmann, P. Mosat, D. Tonev, E. Stefanova
During the last 12 years using the GABRIELA (Gamma Alpha Beta Recoil Invetsigations with the ELectromagnetic Analyser) detector set-up and kinematic recoil separators VASSILISSA / SHELS the experiments aimed to the gamma and electron spectroscopy of the Fm – Db isotopes, formed at the complete fusion reactions 48Ca+207,208Pb → 255,256No*, 48Ca+209Bi → 257Lr*, 22Ne+238U → 260No*, 50Ti+208Pb → 258Rf* and 50Ti+209Bi → 259Db*, were performed at FLNR JINR.
Inclusive energy spectra have been measured for light charged particles emitted in the bombardment of Ta target by 48Ca ions at 261 MeV and 471 MeV. The reaction products were analyzed and detected by means of a (∆ExE) telescope placed in the focal plane of a magnetic spectrometer located at forward angles with respect to the beam direction. In all the reactions studied light charged particles with an energy close to the respective calculated kinematic limit for a two-body exit channel are produced with relatively great probability. The results obtained make it possible to draw some conclusions about the reaction mechanism involving the emission of light charged particles.
Authors: B.M. Hue, T. Isataev, S.M. Lukyanov, K. Mendibaev, A.G. Artukh, D. Aznabayev, C. Borcea, P.V. Cuong, B. Erdemchimeg, S.A. Klygin, G.A. Kononenko, K.A. Kuterbekov, V.A. Maslov, V.Ostashko, Yu.E. Penionzhkevich, F. Rotaru, Yu. Sereda, A.N. Vorontsov, T.D. Thiep
Neutron-removal cross-section ( σ−xn ) measurements of neutron-rich light nuclei were performed on the COMBAS fragment-separator with a multi-detector Si telescope at intermediate energies (22-34) MeV/nucleon. The removals of one neutron from 8Li and 9Be, two neutrons from 6He and 10Be and four neutrons from 8He were observed from the reactions on a Si-CsI(Tl) telescope. Results of σ−xn for 6He, 8He, 8Li, 9Be and 10Be nuclei were obtained and compared with those of previously measured data. The data indicate that 4 He is a good core within 6He and 8He.
Furthermore, we found that 9,10Be nuclei disintegrated by one- and two-neutron removal reaction, respectively.
This paper is a generalization of the authors’ works in the ﬁeld of asphaltene physics fulﬁlled in recent years. Speciﬁc features of the "insulator-semiconductor" phase transition in high-boiling hydrocarbon fractions are discussed. It is shown that the active resistance of the samples decreases with heating to (65 − 85)oC. At the same time, the concentration of paramagnetic centers increases, which is conﬁrmed by the EPR. The growth of electrical conductivity in high-boiling hydrocarbon fractions containing asphaltenes is caused by the temperature generation of charge carriers – free radicals (spins) formed as a result of the rupture of weak carbon-carbon bonds in molecules weakened by conjugation with aromatic rings. The energy of rupture of such bonds is rather low and can be as low as 40 kJ/mol. All these facts conﬁrm the hypothesis of the authors that in the samples a phase transition occurs from the "insulator" state to the "semiconductor" state. The dielectric-semiconductor phase transition is also due to the generation of stable free radicals, since they are strong electron acceptors and reduce the width of the forbidden band of the material. Quantum-chemical calculations conﬁrm this hypothesis. In addition, quantum-chemical calculations of the supramolecular, molecular, and electronic structure of asphaltene nanoparticles have been carried out. An experimental study of asphaltene crystallites by the AFM method was carried out. Theoretical calculations are reasonably conﬁrmed by the AFM data.
We have developed method of preparation of luminescent polymer ﬁlms based on polyvinyl alcohol (PVA), organic dyestilben 420 (St420) and silver nanoparticles (AgNPs). Concentration of St420 which provides most efﬁcient luminescence quantum yield was determined for PVA ﬁlm. It was found that addition of 10 nm AgNPs to St420 samples in PVA leads to increase of absorption intensity and decrease of luminescence intensity. Quenching of emission of St420 by addition of AgNPs is probably due to charge transfer from the dye to metal nanoparticles. External quantum efﬁciency (EQE) curves of St420 PVA were measured for optimal concentration of the dye. Some decrease of EQE curve was observed for down-shifting (DS) layer of St420. At the same time some increase of efﬁcacy ofsolar cell (SC) was observed based on I-V measurements.