abstract

The results of the analysis of the \(^{25}\)Mg\((d,t)^{24}\)Mg and \(^{24}\)Mg\((d,p)^{25}\)Mg reactions performed within the modified DWBA are presented. A possibility of clarifying the values of spectroscopic factors for the \(B\to A+n/p\) configuration is demonstrated using the experimental data on the peripheral \(^{25}\)Mg\((d,t)^{24}\)Mg and non-peripheral \(^{24}\)Mg\((d,p)^{25}\)Mg neutron transfer reactions.

abstract

A study of characteristics of the events of complete destruction of the projectile nucleus in the interactions between asymmetric nuclei for different initial states of the collision is performed. In the interactions of the sulfur nuclei with heavy emulsion nuclei at energy of 200 \(A\)GeV, an anomalous high number of events of complete destruction of the projectile nuclei is observed. The high probability of such events depends on the energy of interaction (it is not detected in the interactions of the sulfur nuclei with emulsion nuclei at the energy of 3.7 \(A\)GeV) on the degree of asymmetry of the interacting nuclei (it is not detected in interactions of the sulfur nuclei with light emulsion nuclei) and on the initial state of interaction (it is not detected in peripheral collisions). These events are characterized by high multiplicity of secondary particles and a narrow peak in the region of small values of average pseudorapidity.

abstract

Gamma astronomy is the only experimental possibility of local sources specifying high-energy cosmic radiation (\(10^{12}\)–\(10^{14}\) eV). In prospect, only neutrino astronomy can supplement the search and study of the galactic and metagalactic objects, where the processes of protons and nuclei acceleration are realized. These processes are accompanied by the generation of gamma quanta and neutrinos, which are not scattered in the magnetic fields of the Universe. Therefore, possibilities of experimental study of the processes and specific stellar objects properties are expanded. Various models and theories of the Universe development are created and tested based on the experimental data obtained in gamma astronomy. Thus, the development of the gamma-astronomical experimental research and observation methods is brought to the fore. The HADRON-55 installation is one of the ground-based gamma-ray detectors that can reliably detect gamma rays with the energies above 1 TeV. In the article, the physical and technical characteristics, the algorithm for registration, and their spatial-energy characteristics of gamma-ray are presented.

abstract

The aim of this work is to investigate the influence of low-lying resonances in the Coulomb breakup of \(^{11}\)Be halo nuclei on a heavy target from intermediate (70 MeV/nucleon) to low energies (5 MeV/nucleon) within the non-perturbative time-dependent approach. The inclusion of the resonant states \(5/2^{+}\), \(3/2^{-}\), and \(3/2^{+}\) of \(^{11}\)Be into the computational scheme leads to a significant improvement of the theoretical model. The method can potentially be useful for interpretation of low-energy breakup experiments on different targets in studying the halo structure of nuclei.

abstract

The \(pp \to \{p p\}_s \pi ^0\), where \(\{p p\}_s\) reaction is an unbound interacting proton pair in the \(^1\!S_0\) final state, was investigated at small angles in the beam energy range of \(T_{\mathrm {beam}}=1.5\)–2.5 GeV. For the \(pp \to \{p p\}_s \pi ^0\) reaction, we obtained the angular dependences of the differential cross section d\(\sigma /\)d\({\mit \Omega }\) at forward angles for several energies, the energy dependences of the cross section at zero angle d\(\sigma /\)d\({\mit \Omega }(0)\) and angular slope \(k\) of the forward cross section. The obtained results confirm the existence of a second peak in the d\(\sigma /\)d\({\mit \Omega }(0)\) energy dependence for the \(pp \to \{p p\}_s \pi ^0\) reaction and allow to estimate its maximum, mass, and width. The change in the sign of the slope \(k\) in comparison with the region of the first peak indicates a change in the reaction dynamics at the energies of \(\sqrt {s} \approx 2.3\)–2.6 GeV.

abstract

The main aim of this work is to determine values of the asymptotic normalization coefficients for \(^{93}\)Zr\(+n\to ^{94}\)Zr. For this aim, the recently measured experimental differential cross section of the neutron transfer reaction \(^{94}\)Zr\((^{12}\)C\(,^{13}\)C\()^{93}\)Zr has been analysed. The modified distorted wave Born approximation has been used for determination of the values of the asymptotic normalization coefficients. It has been shown that this reaction is peripheral. The contribution of the three-body Coulomb dynamics of the main transfer mechanism has been taken into account. New values of the asymptotic normalization coefficients for \(^{93}\)Zr\(+n\to ^{94}\)Zr with their uncertainties have been obtained.

abstract

This paper briefly describes the main ways of digital signal processing. The goal of the digital algorithms is to reduce the dead time of the spectrometry path to tens of nanoseconds without loss of energy and time resolutions. The new \(k\sigma \)-trigger with extrapolation technique is proposed in the paper. The method allows to find overlapped signals almost irrespective of their closeness in time.

abstract

The main purpose of this research is to study the nature of resonance states in the \(^6\)Li nucleus, and effects of cluster polarization on the spectrum of bound and resonance states. The cluster polarization is associated with changes of the size and shape of clusters (interacting nuclei) as they approach each other. To achieve these goals, a microscopic three-cluster model is used. This model takes into account two three-cluster configurations: \(^4\)He\(+p+n\) and \(^3\)H\(+d+p\), which are then projected into four binary channels: \(^4\)He\(+d\), \(^5\)He\(+p\), \(^5\)Li\(+n\), and \(^3\)H\(+^3\)He. These three-cluster configurations made it possible to describe more precisely the internal structure of the \(d\), \(^5\)He, \(^5\)Li, and \(^3\)He clusters, and to take into account their polarizability. It is shown that the used model reproduces well the spectrum of low-lying states of \(^6\)Li. It is found that cluster polarization strongly affects the structure of the bound and resonance states, and significantly changes their energy and width.

abstract

In this paper, the experimental data of the elastic interactions of \(\alpha \)-particles with \(^{11}\)B nuclei at the energies of 40 and 65 MeV are measured. Registration and identification of scattered \(\alpha \)-particles were carried out by a standard \(\Delta E\)–\(E\) method implemented on the basis of a PC/AT personal computer. The angular distributions were analyzed using an optical model and the FRESCO and SPI-GENEO computer codes. It is shown that there is a strong correlation between the real and imaginary parts of the potential, which is expressed in the fact that changes in the real part can be compensated by the corresponding changes in the imaginary part (and vice versa), without changing the quality of the description of the experimental data. A good description of the experimental data has been achieved in the full range of angles with potentials having volume integrals in the range of 250–500 MeV fm\(^{3}\).

abstract

In the present work, the induced activity method in measurements of the cross sections for isomeric state formations in the (\(\gamma , n\)) and (\(n, 2n\)) reactions on nuclei of \(^{86,88}\)Sr are used. The energy dependence of the isomeric ratio in reactions of \(^{86}\)Sr(\(\gamma , n\))\(^{85m}\)Sr at the energy range of 12–35 MeV with the energy intervals of 1 MeV have been obtained. In all calculations, we have used the TALYS-1.6 software package. Finally, we have compared our obtained experimental results with the results of previous works.

abstract

The main purpose of this work is to extrapolate the astrophysical \(S\) factor for the \(^3\)He\((\alpha ,\gamma )^7\)Be reaction to low energies including \(E=0.0\) MeV. For this purpose, the recently measured experimental astrophysical \(S\) factor for the nuclear astrophysical \(^3\)He\((\alpha ,\gamma )^7\)Be reaction has been analysed. The modified two-body potential approach has been used for analysing the experimental data. This method made it possible to extract precisely the values of the asymptotic normalization coefficients. New values of the asymptotic normalization coefficients for \(^3\)He\(+\alpha \rightarrow ^{7}\)Be (0.0 MeV) and \(^3\)He\(+\alpha \rightarrow ^{7}\)Be (0.429 MeV) with their uncertainties have been obtained. The values of the asymptotic normalization coefficients have been used for extrapolation of the astrophysical \(S\) factor to low energies within the modified two-body potential approach.

abstract

Asymmetric fission of mercury nuclei was initially observed in the low-energy region. In recent years, several experiments have been performed in this direction to investigate the asymmetric behaviour of Hg nuclei which supported the influence of shell effects on the asymmetric fission process. An experiment was performed using the CORSET setup. We investigated mass and energy distributions of fragments and fission characteristics of prolately-deformed \(^{182}\)Hg and oblately-deformed \(^{183}\)Hg nuclei formed in the \(^{40}\)Ca\(+^{142,143}\)Nd reactions at three different beam energies — \(E_{\mathrm {lab}}=172\), 192, and 212 MeV. We found no huge variation in mass–energy distributions of \(^{182}\)Hg and \(^{183}\)Hg at any of the measured energies. This gives us an outlook regarding the influence of shell structure, charge radii deformation, and factors associated with the potential energy surface that is responsible for fission in the Hg region.

abstract

The mechanism of simultaneous non-sequential four-neutron emission (or “true” four-neutron decay) has been considered in the phenomenological five-body approach. It is demonstrated that four-neutron decay fragments should have specific energy and angular correlations reflecting strong spatial correlations of “valence” nucleons orbiting in their four-neutron precursors. Due to the Pauli exclusion principle, the valence neutrons are pushed to the symmetry-allowed configurations in the four-neutron precursor structure, which causes a “Pauli focusing” effect. Prospects of the observation of the Pauli focusing have been considered for the hydrogen-7 nucleus. Fingerprints of its nuclear structure or/and decay dynamics are predicted.

abstract

The technique of using a cluster of 9\(\times \)CeBr\(_{3}\)-NaI(Tl) phoswich detectors as a Compton suppression spectrometer for detecting low-energy \(E\gamma \lt 4\) 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 \(\varepsilon _{\gamma }\) and the peak efficiency \(\varepsilon _{\rm {PEAK}}\), 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.

abstract

Interpretation of the spectra of soft photons in transverse momentum in \(pp\) collisions is proposed taking into account the \(X17\) boson with a mass of 17 MeV — a new particle, a possible candidate for the role of dark matter particles. On the basis of combining two-dimensional quantum chromodynamics and quantum electrodynamics in the tube model, the masses of dark matter particles are found. An interpretation is proposed for the detection of a 38 MeV boson in the spectra of photons emitted in the reactions of protons with carbon nuclei at an incident proton momentum of 5.5 GeV/\(c\). The \(X38\) boson with a mass of 38 MeV has a mass close to the boson mass obtained by us, equal to 35 MeV for an electromagnetic tube. This new particle was discovered in experiments carried out recently in Dubna for the \(p+\)C\(\rightarrow 2\gamma +X\) reaction. It was proposed to consider bosons \(X17\) and \(X38\) as particles of dark matter.

abstract

A new analog spectrometer of the DGFRS2 setup installed at new FLNR DC-280 ultra-intense cyclotron has been designed. The main goal of application of this spectrometer is to provide deep backgrounds suppression in different heavy-ion induced nuclear reactions using real-time detection mode of short correlated sequences such as ER-\(\alpha \), \(\alpha \)–\(\alpha \) or even ER-\(\alpha \)–\(\alpha \). Integral 1M CAMAC analog-to-digital processor ExTech ADP-16 is used as a basic unit in the spectrometer design. A new real-time flexible algorithm is presented in addition to the conventional ER-\(\alpha \) one which is in use for a few years at the DGFRS1 setup installed at the U-400 FLNR cyclotron. Note that the spectrometer operates together with the \(48\times 128\) strip DSSD (Double Side Strip Detector) detector and low pressure pentane-filled gaseous detector. To perform the real-time operation mode, we define an abstract mathematical object like “correlation graph” containing \(n(n-1)/2\) links. An experimentalist can use each link as trigger signal for beam stop. Here \(n\) is the number of nodes for this graph. First tests of the spectrometer at intense beam of \(^{48}\)Ca projectile are presented too.

abstract

The purpose of this research is to search and study halo in isobar-analog states of light nuclei. The study of states with a halo in isobar analogs allows one to investigate the manifestation of isotopic invariance at new objects and to relate the properties of the neutron and proton halo. The question of the existence of halo in isobar-analog states has so far not been practically raised in the experimental plan. The proposed approach is based on measuring the radii of states in which the halo exists or can exist. The data on the radii can give new information for solving the long-standing problem of a single description of the halo in both parts of the spectrum — discrete and continuous. We propose to solve problem: experimentally determine the radii of a number of states in which there can be a halo in nuclei, forming isobar-analog doublets and triplets. We have discovered new possible candidates for a halo in the isobar-analog multiplets \(A=12\) and \(A=14\). First, most of the states lie in the continuous spectrum. Second, the results were obtained within the framework of two independent methods: ANC and MDM. A great achievement was the development of the ANC method for studying resonance states, which made it possible to identify new cases of a proton halo in isobaric analog states.

abstract

\(^{13}\)C is a good example of a “normal” nucleus that is well described within the shell model. Its level scheme is reliably determined up to excitation energies \(\sim \) 10 MeV. However, some questions remain open regarding the structure of low-lying \(^{13}\)C states. This leads to the increased attention to \(^{13}\)C. In 2014, our group announced the discovery of a state of \(^{13}\)C with an abnormally small radius. In the framework of the modified diffraction model (MDM) method, analyzing data on \(\alpha \)-scattering on \(^{13}\)C at 65 and 90 MeV, it was shown that this state has a radius reduced by 10%. At the same time, theoretical works predict dilute structure and increased radius for this state, and assumptions were made about its rotational structure. Another important question is the search for possible analogues of the Hoyle state in \(^{13}\)C. Confirmed analog of the Hoyle state is the 1/2\(^{-}\) (8.86 MeV) state in \(^{13}\)C. Another possible candidate is the next 1/2\(^{-}\) state — 11.08 MeV. Moreover, a hypothesis was put forward about a new type of symmetry in the \(^{13}\)C structure — \(D^\prime _{3h}\) symmetry. On the basis of \(D^\prime _{3h}\) symmetry, the rotational nature of a whole group of low-lying \(^{13}\)C states was predicted. In the work, 6 rotational bands were proposed, that is, almost all low-lying \(^{13}\)C states were distributed among the rotational bands. Thus, a critical analysis of the available data is required to answer the question about the nature of low-lying excited states in \(^{13}\)C.

abstract

We have shown that the effects of nonadiabaticity, observed in the magnetic characteristics can be satisfactorily explained by the Coriolis mixing of the states of the rotational bands in \(^{156}\)Gd.

abstract

The exclusive \(^{12}\)C\(+p\to ~^{10}A+pp+N\) reaction, where the \(^{12}\)C beam at the energy of 4 GeV/nucleon interacts with the proton target and as a result, one proton is knocked-out from a short-range correlated \(NN\) pair in \(^{12}\)C, was measured recently by the BM@N Collaboration. This reaction is considered here by analogy with the theory of quasi-elastic knockout of fast deuterons from nuclei \((p,Nd)\) using the translationally-invariant shell model with short-range \(NN\) correlations. The initial- and final-state interaction effects are estimated in the eikonal approximation using the Glauber model for elastic \(N\)–\(^{10}\! A\) scattering.

abstract

A three-body model \(\alpha + 2N\) for \(^6\)He is applied using the wave function obtained within the stochastic variational method based on the Gaussian basis. An explicit expression is obtained for the density distribution function of nuclear matter. The elastic scattering of \(^6\)He by \(\alpha \)-particles is studied in detail. By employing the calculated density distribution functions, the folding interaction potentials are built. The resulting folding potential is applied to calculate the differential cross sections of elastic scattering in the framework of the optical model. In order to treat the excess experimental cross sections at the large angles, the mechanisms of two nucleon transfer are proposed. With the proposed theoretical approach, good agreement in the comparison of calculated differential cross sections with the experimental data is demonstrated. It is also shown that the two-step transfer mechanisms of two nucleons predominate over one-step transfer mechanisms.

abstract

To study the \(^{11}\)B cluster states, in this work, experiments were carried out on the elastic scattering of 14.5 MeV deuterons by \(^{11}\)B at the U-150M cyclotron (INP, Almaty, Republic of Kazakhstan) phase analysis (PFA). Using the PFA from oscillations of Fraunhofer-type diffractions of experimental angular distributions of differential cross sections of elastically scattered ions on target nuclei, the parameters of the S-matrix were determined by the method of fitting using the unique minimum Pearson values for ten pairs of free parameters of the theory. The paper presents experimental data on the elastic scattering of deuterons with \(E_d = 14.5\) MeV on the \(^{11}\)B target for the ground state in comparison with experimental world data. From the performed analysis, the values of the interaction radii and the blurring of the edge of the \(^{11}\)B nucleus were obtained.

abstract

Double-differential protons and \(\alpha \)-particles emission cross sections were measured for proton-induced reactions on \(^{103}\)Rh nucleus at the incident energy of 22 MeV. The experiment was performed at the isochronous cyclotron of the Institute of Nuclear Physics (Kazakhstan). After integrating the double-differential cross sections over the angle, the integral cross sections of \(^{103}\)Rh(\(p,xp\)) and (\(p,x\alpha \)) reactions were obtained and compared with the TENDL-2019 evaluation. In general, the calculated spectra were in good agreement with the measured ones.

abstract

The isomeric ratios of the yields of photoneutron reactions (\(\gamma , n\)) on a \(^{140}\)Ce nucleus have studied in the energy range of 12–35 MeV with a step of 1 MeV. The resulting energy dependence has been obtained in the form of a saturation curve. The experiments have been carried out by the induced activity method. The cross sections for the excitation of the \(^{139m,g}\)Ce isomeric states in the (\(n, 2n\)) reaction on the \(^{140}\)Ce nucleus at a neutron energy of 14.1 MeV have also been determined. Finally, the obtained experimental results have been compared with theoretical and numerical calculations performed using the TALYS-1.6 software package.

abstract

A new detector system consisting of 116 \(^3\)He neutron counters and a DSSSD array was created. This system can be used to study spontaneous fission properties of short-lived heavy isotopes. The single neutron registration efficiency of the counter assembly was measured as \(54.7\pm 0.1\)% with the \(^{248}\)Cm source. Using the setup, new data were obtained for prompt neutron yields of \(^{252}\)No isotope.

abstract

We have described the clusters search methods in detail. These methods were applied to \(\bar p p \rightarrow \bar p p\pi ^+\pi ^-\) reaction at 32 GeV/\(c\) momentum and we have separated 7 clusters. The features of those clusters were obtained. This reaction is dominated by two production mechanisms, one-vertex fragmentation and simultaneous two-isobars excitation (two-vertex fragmentation). For a detailed study of one-vertex fragmentation, the clusters search method has been used in the rest frame of three particles selected from the final state and 6 clusters have been separated. The study of them shown the essential role of resonances amplitudes interference.

abstract

The total neutron cross sections for nitrogen, oxygen, aluminum, and silicon of natural isotopic composition were measured at the energy of \(E_n=14.1\) MeV. The measurements are the continuation of the previous study using a new simple method based on the NG-150 neutron generator of the INP AS, Uzbekistan. The obtained values are in good agreement with the literature data at the nearby energies. These and the published experimental \(\sigma _{\mathrm {tot}}\), as well as the available data on the elastic neutron scattering, were used to specify the parameters of the phenomenological optical \(n+A\) potentials, which are now in demand for calculations of cross sections of nuclear-astrophysical processes involving light nuclei.

abstract

The motion of charged particles emerging from a point source located in the middle plane of the transaxial mirror is considered. It is shown that as a result of reflection in a three-electrode transaxial mirror, a parallel volume beam can be formed. To calculate the trajectories of particles, the dimensionless Newton equations and analytical expressions for the potential are used, which describe the field of a three-electrode transaxial mirror with good accuracy. Two modes of vertical beam focusing are calculated. The transaxial mirrors can be used to create highly efficient time-of-flight mass spectrometers.

abstract

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 \(\pm 5\) 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.

abstract

YDA (Yury and DAstan) Builder C++ PC-based code has been developed. It allows to provide data acquisition using 48\(\times \)128 DSSSD (Double Side Silicon Strip Detector) and multiwire pentane filled low-pressure gaseous detector. The main feature of the developed program package is to use flexible real-time algorithms to provide in-fact background-free conditions for ultra-rare alpha decays registration. Three scenarios of these algorithms are under consideration. Two of them deal with the relatively low rate of beam stops, whereas the third one corresponds to a high beam stop rate. First results of YDA code application are presented. The example of an iteration process to obtain an optimizing recoil-alpha time interval value is presented too. Part of visualization programs are written in Python.