F. M. Pen’kov

Quantum transmittance of barriers for composite particles

The transmission of two bound particles through a repulsive barrier is studied. A simple mechanism for the appearance of barrier resonances, which results in anomalous barrier transmittance as compared with the transmission probability for structureless objects, is demonstrated. It is shown that the probabilities for two interacting particles to tunnel from a false vacuum can be much higher than previously thought.

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.

Measurement of the astrophysical S factor for dd interaction at ultralow deuteron-collision energies using the inverse Z pinch

This paper is devoted to measurement of the astrophysical S factor and cross sections of the d + d → 3He + n reaction at ultralow deuteron-collision energies. Formation of the flow of the accelerated deuterons incident on the CD2 solid-state target was made within the scheme of the inverse Z pinch. The liner in the initial state was a hollow supersonic deuterium jet of radius of 15 mm and length of 20 mm. The experiment was carried out at the pulsed high-current accelerator (I=950 kA, τ=80 ns) of the Institute of High-Current Electronics (Tomsk, Russia). Measurement of the deuteron energy distribution was performed through an analysis of the time distributions of the intensity of the liner radiation (Hα and Hβ lines) generated during the liner radial movement from the axis. Recording of this radiation was carried out by optical detectors placed along the direction of the liner moving from its axis. The measured value of the astrophysical S factor for the dd reaction at the average deuteron collision energy Ecoll=3.69 keV was equal to S(Ecoll=3.69 keV)=58.2±18.1 keV b. The dd-reaction cross section calculated using the found value of the S factor and known representation of the reaction cross section as the product of the barrier factor and the astrophysical S factor was σddn(Ecoll=3.69 keV)=(1.33±0.41)×10−30 cm2.

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.

Astrophysical S factor for dd interaction at ultralow energies

Experimental results are presented that were obtained by measuring the astrophysical S factor for dd interaction at very low deuteron collision energies by using the liner-plasma technique. The experiment was performed at the high-current generator of the High-Current Electronics Institute (Tomsk, Russia). The values found for the S factor at the deuteron collision energies of 1.80, 2.06, and 2.27 keV are Sdd=114±68, 64±30, and 53±16 keV b, respectively. The corresponding dd cross sections obtained as the product of the barrier factor and the measured astrophysical S factor are σddn(Ecol=1.80 keV)=(4.3±2.6)×10−33cm2, σddn(Ecol=2.06 keV)=(9.8±4.6)×10−33cm2, and σddn(Ecol=2.27 keV)=(2.1±0.6)×10−32cm2.

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.

Study of the pd reaction at ultralow energies using hydrogen liner plasma

AbstractThe pd reaction (pd → He + γ (5.5 MeV)) is studied in the astrophysical energy collision range of protons with deuterons using the hydrogen liner in the inverse Z-pinch configuration at the pulsed power generator MIG (HCEI, Tomsk). Fundamental characteristics of this and other light-nucleus reactions at ultralow energies are important for problems of basic physics and astrophysics. The knowledge of the energy distribution of the nuclei participating in these reactions is important due to their exponential type of dependence on the collision energy. Two experimental techniques were designed and tested for recovering the energy distribution of liner protons incident on the CD2 target by using optical detectors and ion collectors. It is shown that the combined use of these two techniques could provide relevant information on the energy distribution of the accelerated protons in the liner. The estimates of the upper limits for the astrophysical S factor and effective cross section of the pd reaction in the proton-deuteron collision energy range of 2.7–16.7 keV are obtained:

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

\bar S_{pd} (E_{pd} = 10.2 keV) \leqslant 2.5 \times 10^{ - 7} MeV b;\overline \sigma _{pd} (2.7 \leqslant E_{pd} \leqslant 16.7 keV) \leqslant 4 \times 10^{ - 33} cm^2