^7 Li elastic scattering and the lithium-induced reaction of one-nucleon transfers from ^10 B( ^7 Li, ^6 Li) ^11 B have been measured at E_LAB ( ^7 Li) = 58 MeV using U-400 accelerator beam of the FLNR JINR, Dubna. Angular distribution for reaction ^10 B( ^7 Li, ^6 Li) ^11 B with excitation of the 3.56 MeV state ( ^6Li^* ) is presented for the first time. The ‘‘Finite Range Distorted Wave Born Approximation’’ (FRDWBA) analysis of the differential cross section of the ^10 B( ^7 Li, ^6 Li) ^11 B ground state (g.s.) transition and excited ( J^π=0^+ , T=1 , E=3.56 MeV) state of ^6 Li transition was performed. Phenomenological approach based on solving an approximate equation for the reaction form factor was used to determine its radial dependence and empirical values of asymptotic normalization coefficient (ANC). The obtained values of ANC for the ^6 Li _g.s and ^6Li^* (3.56 MeV) states are in agreement with the literature ones. Comparison of the radial dependences of form factors shows that the wave function of the ^6 Li nucleus in excited ( J^π=0^+ , T=1 , E=3.56 MeV) state has increased spatial dimension compared to the ground state. This result is an argument in favor of a halo existence in ^6Li^* (3.56 MeV) state, while the question of a halo in ^6 Li _g.s. still stays open.

The 4π methods used to measure total reaction cross sections σR are presented; they are based on the detection of prompt γ rays and neutrons by scintillation spectrometers with a solid angle Ω close to 4π. The experimental setup based on a 12-detector CsI(Tl) spectrometer (Ω = 0.96 × 4π) is described, which has been used in experiments on measuring σR(E) for reactions with radioactive isotopes of He, Li, and Be. The above methods and the σR(E) measurement results for the 6He + 28Si,59Co,181Ta reactions are analyzed. The advantage of the method allowing for multiplicity of γ rays is shown.

An Erratum to this paper has been published: https://doi.org/10.1134/S0020441224050014

In this paper, the results of measurements of the total cross sections for the reactions $^{10,11,12}$Be+$^{28}$Si and $^{14}$B+$^{28}$Si in the beam energy range $13A$--$47A$ MeV are presented. The experimental cross sections were obtained by detection of the gamma quanta and neutrons accompanying the interaction of the isotopes of Be and B with $^{28}$Si. It was found that the cross sections for $^{11,12}$Be are similar, but significantly exceed those for $^{10}$Be. A significant increase in the cross sections for $^{12}$Be with decreasing energy is observed in the entire measured energy range. A theoretical explanation of the obtained experimental data is given based on the microscopic model of deformed nuclei and the numerical solution of the time-dependent Schrödinger equation for the outer weakly bound neutrons of the projectile nuclei. The calculated total reaction cross sections are in good agreement with the experimental data.

The energy spectra of alpha particles emitted at an angle of 0 $${}^{\circ}$$ in the interaction of 400-MeV $${}^{56}$$ Fe ions with $${}^{238}$$ U, $${}^{181}$$ Ta, and $${}^{9}$$ Be targets were measured by means of a high-resolution magnetic analyzer (MAVR, which is the acronym of the Russian name of this setup). The energy spectra of charged particles ranging from Li to Ne were also measured. The experimental data obtained in this way indicate that the emission of alpha particles is a dominant process in the above reactions. Particles of high energy, up to those in the vicinity of the so-called kinematical limit for two-body reactions, were observed with a rather high yield. The sensitivity of the experimental procedure that employed the aforementioned magnetic analyzer made it possible to observe events characterized by cross-section values smaller by six to eight orders of magnitude than that at the maximum of the spectrum. The cross section for the production of light particles is shown to be dependent on their binding energy in the target. The experimental data obtained in this study were analyzed with aid of the moving-source model.

The values of the total cross sections σ R of the 8 Li, 8 He + 28 Si, 59 Co, 181 Ta reactions in the beam energy range from 6 to 46 A MeV have been measured for the first time using registration of the prompt neutron and gamma radiation by a 12-detector 4π-gamma spectrometer. The values of the cross sections and the multiplicity distributions for the emission of γ quanta and neutrons were calculated with consideration of the distributions over the number of triggered detectors. Analysis of the neutron multiplicity distributions was performed based on the statistical model. A microscopic description of nuclear collisions was performed based on the numerical solution of the time-dependent Schrödinger equation for the loosely bound outer neutrons of projectile nuclei.

The energy spectra of alpha particles from reactions induced by 280-MeV $${}^{48}$$ Ca beams incident to $${}^{181}$$ Ta, $${}^{197}$$ Au, and $${}^{238}$$ U targets were measured at an angle of 0 $${}^{\circ}$$ by means of a high-resolution magnetic analyzer (MAVR setup). The sensitivity of the procedure used made it possible to measure alpha-particle yields that are five to six orders of magnitude less than the maximum yield. The cross section for the formation of alpha particles is shown to be dependent on their binding energy in the target nucleus. The experimental data obtained from these measurements were analyzed on the basis of the model of two- and three-body reaction channels and the model of moving sources.

New semiconductor detectors based on CdZnTe and CeBr3 crystals are tested. A spectrometer facility consisting of CdZnTe, CeBr3, and Si (for α–γ measurements) detectors is assembled for verification tests. The main parameters of the detectors such as energy resolution FWHM/Eγ [keV] and detection efficiency (%) are investigated and measured. The possibilities of measuring photon radiation in a wide energy range are verified. γ–γ and α–γ coincidences are measured using the detectors. The results of the measurements show that the detectors can be used to study nuclear reactions and properties of reaction products.

The differential cross sections for alpha-particle emission at an angle of 0 $${}^{\circ}$$ in the reactions induced by a 6-MeV/nucleon $${}^{56}$$ Fe beams incident to $${}^{238}$$ U and $${}^{181}$$ Ta targets were measured versus the alpha-particle energy by means of a high-resolution magnetic analyzer (MAVR setup). The resulting spectra were found to contain fast alpha particles of energy corresponding to the two- and three-body exit reaction channels, including alpha particles of energy close to the two-body kinematical limit. The data obtained in this experiment were analyzed on the basis of the moving-source model. The emission of nonequilibrium alpha particles in the forward direction from the heavier target nucleus upon the complete or incomplete fusion of nuclei was revealed within the time-dependent quantum approach.

The technique of using a cluster of 9xCeBr(3)-NaI(Tl) phoswich detectors as a Compton suppression spectrometer for detecting low-energy E gamma < 4 MeV gamma-radiation is investigated. The characteristics of a phoswich detectors cluster and a High-Purity Germanium detector (HPGe) with a BGO shield are compared. The main characteristics of gamma-ray spectrometer: the energy resolutions Delta E, the total registration efficiency epsilon gamma and the peak efficiency epsilon PEAK, depending on the energies E gamma of the registered gamma-rays and on the distances to the source, are presented. It is shown that the Compton suppression coefficient values of both spectrometers are the same, while the peak efficiency of the phoswich cluster is three times higher than in the HPGe detector. The Compton suppression mode of the phoswich cluster is supposed to be used for studying beta-delayed gamma-decay processes, particularly direct gamma-decay of Pygmy resonances.

The heavy-ion reactions are characterized by a large number of channels, differing in various characteristics (angular distributions, mass distributions, kinetic energy, reaction cross sections, etc.). The major characteristics of two complex nuclei interaction processes is the mass distribution of reaction products. Therefore, one of the main features of the experiment is a direct measuring of the reaction products masses. This is directly achieved by measuring the masses of the forming nuclei. This paper describes the results of direct measuring of the reaction products masses using a precision time-of-flight technique. Tn this technique, microchannel plates (MCP) are used as the start and stop detectors. Using the 25 cm path length, time resolution of 240 ps was obtained, which made it possible to determine the nuclei masses with an accuracy of +/- 5 amu. The technique is applied in experiments to measure the heavy nuclei fission fragments characteristics (mass distribution and total kinetic energy), in reactions of complete and incomplete heavy ions fusion with nuclear targets.

A time-of-flight system was created to register the reaction products and perform correlation measurements on a high-resolution magnetic analyzer (MAVR). The facility is located on the channel of the extracted beam of the U-400 cyclotron at the Laboratory of Nuclear Reactions JINR. The results of measuring the parameters of the time-of-flight spectrometer obtained on the basis of measuring the spontaneous fission fragments velocities of 252Cf are described. In addition, the results of the measurement of fission fragments in the 48Ca+238U reaction are presented. In this case, two time-of-flight arms were used, with the help of it is planned to carry out correlation measurements of induced fission fragments of a complex system. The created system also makes it possible to carry out correlation (three particles) measurements of fission fragments with particles registered in the focal plane of the MAVR magnetic spectrometer. Another purpose of the described system is to register elastically scattered ions, which is used as a monitoring system for the quality and composition of the beam hitting on the target of the MAVR facility.

A detection setup for the direct measurement of the total reaction cross section with exotic nuclei is presented. The setup consists of a multi-detector telescope for beam-particle identification and a 4 pi gamma-ray spectrometer for the detection of prompt photons and neutrons accompanying the nuclear reactions. Measurements are based on the modified transmission method and gamma-ray tagging of nuclear reaction events. Registration efficiency and response characteristics of the gamma-ray spectrometer are investigated by Monte Carlo simulations and measurement with Co-60 spectroscopic source. Results show strong a dependence of the registration efficiency on gamma-ray multiplicity, with minimum registration efficiency value of 70%. Evaluation of the registration efficiency for data measured in the total reaction cross section experiments is discussed.

The availability of new radioactive ion beams has broadened the study of nuclear reactions and nuclear structure. The main mechanism to produce the secondary beams is the fragmentation of the projectile. An alternative method for the production of the exotic nuclei is the multinucleon transfer. We measured production cross section for the B, C, N and O isotopes in the reaction 18O + Ta and the beam energy at 10 MeV/nucleon. The cross-sections were obtained by integrating the momentum distributions of the isotopes. It was shown that in deep inelastic processes the production yields of different isotopes could be well described using statistical models and could also be explained by the Qgg-systematic.

Experiments with 6,8 He, 9 Li + 28 Si, 59 Co, and 181 Ta reactions in the energy range of 6,8 He and 9 Li beams 6–36 A MeV have been preformed. Prompt neutrons and gamma radiation were registered by a 12‑detector gamma spectrometer. The values of the total reaction cross sections and the multiplicity distributions for the emission of γ-quanta and neutrons were calculated taking into account the distributions over the number of triggered detectors.

The results of experiments performed at a high-resolution magnetic spectrometer (MAVR) are presented. The differential production cross sections for oxygen isotopes in the $${}^{18}\textrm{O}+^{181}$$Ta reaction at the projectile energy of 10 MeV per nucleon were measured at the MAVR facility. The yield of reaction products is analyzed theoretically in the finite-range distorted-wave Born approximation (FR-DWBA method) by means of the FRESCO code. The theoretical differential cross sections are calculated for sequential neutron transfer. The contributions of the mechanisms of sequential neutron transfer and dineutron-cluster transfer to the production cross sections for the neutron-rich oxygen isotopes $${}^{20,22,24}$$O are studied.