A. P. Kobzev

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 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.

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.

Measurements of a partial cross section for the reaction 58Ni(n, γ0)59Ni

The partial cross section for radiative neutron capture accompanied by gamma transitions to the ground state of the 59Ni nucleus was measured as a function of energy by a new neutron-spectrometry method that employed the shift of a primary gamma transition in response to a change in the energy of the captured neutron. The reaction 7Li(p, n)7Be was used as source of neutrons for the present measurements. The protons that induced this reaction were accelerated by a Van de Graaff electrostatic generator to energies exceeding the reaction threshold by 60 keV, in which case an appropriate geometry of the experiment permitted irradiation of the sample under study with neutrons whose energy ranged between 10 and 120 keV. The partial widths of some resonances and radiative strength function for hard primary M1 gamma transitions were determined in addition to the above cross sections.

A Hemispherical Fission Chamber for the Neutron-Flux Monitoring

A fission ionization chamber has been designed to monitor neutron fluxes produced by the proton beam of the Van de Graaf accelerator in the 7Li(p, n)7Be nuclear reaction. A target producing neutrons is placed at the center of the chamber, which has a hemispherical shape. The neutrons escaping from the target are detected within the limits of a space angle a little larger than 2π sr. A 235U isotope is used as a fissile material. A U3O8 layer with a thickness of 300 μg/cm2 and an area of 80 cm2 has already been deposited on the surface of the inner hemisphere using electrolysis. The chamber is filled with a gas mixture of 97% Ar + 3% CO2. The detection efficiency of the chamber for neutrons with 1- to 150-keV energies is found to be 1.6 × 10–5. Using this chamber, it is possible to measure (with a statistical accuracy of 1%) the integrated neutron yield in a thick target exposed for ∼20 min to a proton beam with a current of ∼3 μA and an energy of 1942 keV, which is 60 keV above the threshold of the 7Li(p, n)7Be reaction. The design of the fission chamber is described, and the test results are presented.

Measurements of the partial cross section for the reaction 48Ti(n, γ1)49Ti and estimation of the radiative strength functions for E1 and M1 transitions

The partial cross section for radiative neutron capture by 48Ti nuclei was measured as a function of neutron energy. The method of neutron spectrometry used is based on the shift in the energy of the primary γ transition in response to a change in the energy of the captured neutron. The reaction 7Li(p, n)7Be was used as a neutron source. Protons were accelerated by a Van de Graaff electrostatic generator up to energies of 60 keV above the reaction threshold, which provided neutron energies in the range from 10 to 120 keV. The partial widths of some resonances were determined. The radiative strength functions of E1 and M1 transitions to the first excited state were calculated.

keV – Neutron Spectrometry Method for Partial Cross Section Measurements

The reported neutron spectrometry method is based on primary γ-transition energy shifts. It has been demonstrated in measurements of the partial radiative capture cross section of the 58Ni(n,γ)59Ni and 48Ti(n,γ1)49Ti reactions. The reaction 7Li(p,n) is used to produce resonance neutrons by means of the proton beam of a Van de Graaff accelerator. A compact geometry allows one to improve the luminosity and to employ a rather wide neutron spectrum of up to ~100 keV. Both partial radiative parameters of some neutron resonances and partial cross sections for population of the low-lying states of the product nuclei are obtained.