Yu. Zh. Tuleushev

Study of the d(p, γ)3He reaction at ultralow energies using a zirconium deuteride target

Abstract The mechanism for the d ( p , γ ) 3 He reaction in the region of ultralow proton–deuteron collision energies (6.67 E S -factor and the effective pd reaction cross section on the proton–deuteron collision energy are measured. The results are compared with the available literature data. The results of this work agree with the experimental results obtained by the LUNA collaboration with the target of gaseous deuterium.

Investigation of temperature dependence of neutron yield and electron screening potential for the d(d, n)3He reaction proceeding in deuterides ZrD2 and TiD2

The temperature dependence of the enhancement factor for the dd reaction proceeding in TiD2 and ZrD2 is investigated. The experiments were carried out at the Hall pulsed ion accelerator (INP, Polytechnic University, Tomsk, Russia) in the deuteron energy interval 7.0–12.0 keV and at temperatures ranging from 20 to 200°C. The values obtained for the electron screening potentials indicate that the dd reaction enhancement factor does not depend on the target temperature in the range 20–200°C. This result contradicts the conclusions drawn by the LUNA Collaboration from their work.

Novel superconducting niobium beryllide Nb3Be with A15 structure

New niobium beryllide Nb3Be with A15 structure and lattice parameter a=0.5187±0.0007 nm, coexisting (3–5%) with a tetragonal phase, presumably, of an ordered solid solution with parameters a=0.5414±0.0008 nm and c=0.6378±0.0009 nm, was synthesized by thermal treatment (875–110°C) of amorphous film coatings containing 26.8–32.4 at. % Be and formed from short-period Nb and Be layers by magnetron sputtering. The domain of existence of the Nb3Be phase and the critical superconducting transition temperature (10.0 K and a transition width of 2.5 K) were determined and the X-ray structural data for structure identification were obtained.

Measurement of astrophysical S factors and electron screening potentials for d ( d, n ) 3 He reaction In ZrD 2 , TiD 2 , D 2 O, and CD 2 targets in the ultralow energy region using plasma accelerators

The paper is devoted to study electron screening effect influence on the rate of d(d, n)3He reaction in the ultralow deuteron collision energy range in the deuterated polyethylene (CD2), frozen heavy water (D2O) and deuterated metals (ZrD2 and TiD2). The ZrD2 and TiD2 targets were fabricated via magnetron sputtering of titanium and zirconium in gas (deuterium) environment. The experiments have been carried out using high-current plasma pulsed accelerator with forming of inverse Z pinch (HCEIRAS, Russia) and pulsed Hall plasma accelerator (NPI at TPU, Russia). The detection of neutrons with energy of 2.5MeV from dd reaction was done with plastic scintillation spectrometers. As a result of the experiments the energy dependences of astrophysical S factor for the dd reaction in the deuteron collision energy range of 2–7 keV and the values of the electron screening potential Ue of interacting deuterons have been measured for the indicated above target: Ue(CD2) ⩽ 40 eV; Ue(D2O) ⩽ 26 eV; Ue(ZrD2) = 157 ± 43 eV; Ue(TiD2) = 125±34 eV. The value of astrophysical S factor, corresponding to the deuteron collision energy equal to zero, in the experiments with D2O target is found: Sb(0) = 58.6 ± 3.6 keV b. The paper compares our results with other available published experimental and calculated data.

Effect of the crystal structure of a deuterated target on the yield of neutrons in the dd reaction at ultralow energies

The energy dependence of the neutron yield in the d(d, n)3 He reaction proceeding in a textured titanium deuteride target with the preferred orientation of microcrystals in the [100] direction has been studied. Measurements have been performed for the energy range of incident deuterons of 7–12 keV in the laboratory system. It has been shown that the energy dependence of the enhancement factor of the reaction is described not only by the screening potential but also by the simple inclusion of channeling effects.

Tantalum-cadmium film coatings: Preparation, phase composition, and structure

Ion-plasma sputtering and codeposition of ultrafine Ta and Cd particles were used for the first time to prepare solid solutions, namely, alloys with up to 66.2 at % Cd in the form of coatings; the fact of such a production confirms the thermal-fluctuation melting and coalescence of small particles. When the coatings are formed by tantalum and cadmium nanolayers, the mutual dissolution of the components takes place, which is accompanied by the formation of solid solutions of one metal in the other. When the cadmium concentration is above 44 at %, the β-Ta tetragonal lattice transforms into the α-Ta body-centered cubic lattice. Beginning from 74.4 at % Cd, a hexagonal structure typical of cadmium is formed, and tantalum is present in the coatings in the form of amorphous phase. The formation of β-Ta- and Cd-based interstitial and α-Ta-based substitute solid solutions is stated. At 700°C, cadmium evaporates from Ta-based solid solutions, and porous tantalum is formed. The evaporation of cadmium from coatings, which consist of the mixture of tantalum solid solution in cadmium and amorphous tantalum, leads to the formation of tantalum characterized by a highly developed surface. The prepared Ta-based materials assume the technological application of the results of the investigation.

Measuring the astrophysical S factors and the cross sections of the p(d, γ)3He reaction in the ultralow energy region using a zirconium deuteride target

The present paper is dedicated to the study of the p(d, γ)3He reaction mechanism with the use of a zirconium deuteride target at proton energies of 11–19 keV. The experiment has been carried out using a proton beam of a high-current pulsed Hall accelerator at the National Research Tomsk Polytechnic University. The dependences of the astrophysical S factor and the effective cross section of the pd reaction on the proton-deuteron collision energy are measured. The results were compared with the available data. The results detailed in the present work agree with the results of an experiment carried out by the LUNA collaboration with the use of a gaseous deuterium target.

First experimental evidence of D(p, γ) 3 He reaction in titanium deuteride in ultralow collision energy region

The article is devoted to the investigation of a pd-reaction (p + d → 3He + γ(5.5 MeV)) under-going in titanium deuteride in astrophysical collision energy region of protons and deuterons ranging from 5.3 to 10.5 keV. The experiments have been performed using the Hall NR TPU (Tomsk, Russia) pulsed plasma accelerator. The number of accelerated protons in 10 μs pulse was 5 × 1014 at a repetition rate of 7 × 10−2 Hz. Detection of 5.5 MeV gamma rays was carried out using eight detectors based on crystals of NaI(Tl) (100 × 100 × 400 mm) placed around the TiD target. For the first time, the dependencies between the astrophysical S-factor and the effective cross section of the pd-reaction from proton-deuteron collision energy, and the potential electronic screening of the interacting protons and deuterons in titanium deuteride have been measured.

Nanosize β-tantalum coatings: Formation, structure, and properties

Using the methods of ion-plasma sputtering and the coprecipitation of ultradispersed Ta and Cu particles, Ta-Cu film coatings have been obtained in the whole range of concentrations. The structural analysis supports the existence of copper solid solutions in -tantalum in the range of 1.5–82.4 at % Cu. The dynamics of the variation of the β-tantalum lattice parameters with increasing copper concentration is described. A computer simulation model for constructing the unit cell of copper solution in -tantalum is proposed. The resistivity of the samples of Ta-Cu alloys at room and liquid-helium temperatures is measured. The alloy obtained is established to possess a chemical resistance to a full-strength nitric acid up to 66.6 at % Cu. The dependence of the electrochemical potential of Ta-Cu coatings on copper concentration is studied. It is shown that the presence of minima at 73.7 at % Cu fairly well corresponds to acid-resistance threshold and is related to the binding-energy changes and to Cu atoms arrangement in β-Ta lattice upon transition from the tantalum-based solid solutions to the copper-based solutions.

Structure of sputter-deposited films of β-tantalum-aluminum alloys

Ion-plasma sputtering and the codeposition of ultradisperse particles of Ta and Al have been used to prepare solid solutions in the entire range of concentrations of the binary system in the form of alloy coatings. The formation of the solid solution of these alloys directly in the process of codeposition confirms the theory of the thermofluctuation melting of small particles and coalescence of quasi-liquid clusters of subcritical size. Upon the formation of coatings via the deposition of nanolayers of tantalum of less than 0.8 nm for β-Ta and 1.1 nm for Al, the spontaneous mutual dissolution of the components occurs with the formation of solid solutions of one metal in the other. Beginning with a concentration of ∼85 at % Al in the alloy, Al atoms control the type of symmetry of the arising lattice. An increase in the characteristic dimensions (thickness of sublayers) of tantalum and aluminum leads to the appearance of solid solutions of these metals in these coatings in addition to the β tantalum and aluminum phases, as well as of amorphous regions and superlattices formed by nanoclusters of one metal in the matrix of the other. It has been established that the formation of these superlattices is controlled by the size factor.