Events of the α fragmentation of the 12C and 16O nuclei in nuclear track emulsion in inelastic interactions with 7 GeV/c positively charged hadrons has been studied in 4π geometry. The accumulated event statistics has allowed us to estimate the cross section for the 12C(h, h')3α and 16O(h, h')4α fragmentation reactions induced by a hadron beam.

A calibration procedure with 22Na radioactive sources for the counters of a gamma-nuclear transition spectrometer, which is fully integrated in the infrastructure of the Hyperon+ setup, including trigger and data acquisition systems, is proposed and implemented.

Inclusive spectra of the kaons produced in ArSc collisions as functions of their transverse momentum p_T at mid-rapidity have been calculated within the approach based on the assumption of the similarity of inclusive spectra of the hadrons produced in nucleus–nucleus collisions at their small transverse momenta in the mid-rapidity region taking into account the quark-gluon dynamics in nucleon–nucleon interactions. This article gives a satisfactory description of NA61/SHINE data on p_T -spectra of the K^± mesons produced in ArSc collisions at the mid-rapidity ( y≃ 0).

The status of the study of multiple fragmentation of 950 MeV per nucleon Kr nuclei in a nuclear track emulsion aimed at determining the contributions of 2 α decays of ^8 Be, the Hoyle 3 α state, and the search for a 4 α particle condensate state, is presented. In events with the production of few relativistic fragments of He and H, the possibility of estimating the multiplicity of neutrons in the fragmentation cone of a projectile nucleus is studied. For the planar component of neutron transverse momenta estimated from the angles of observed secondary stars, the Rayleigh distribution parameter was 35± 7 MeV/ c . The importance of such events for the interpretation of cosmophysical observations is noted.

A new time-of-flight (ToF) system of the NA61/SHINE hadron spectrometer at the extracted beam of the Super Hadron Synchrotron in CERN has been developed in 2019–2022 by the staff of the Laboratory of High-Energy Physics of the Joint Institute for Nuclear Research. The new ToF system is based on Multigap Resistive Plate Chambers (MRPCs) technology. The previous system consisting of scintillation counters was substituted with the new ToF system. This paper presents the overview of the new NA61/SHINE ToF system.

Further development of the approach to the study of relativistic nuclear interactions in the space of four-dimensional velocities using the similarity principle is reported. In essence, the approach is modified by including quark–gluon dynamics in hadron generation during nucleus–nucleus interactions in the central rapidity region. Inclusive spectra of pions and kaons produced in pp and nucleus–nucleus, collisions are studied as a function of their transverse momentum pT in the central rapidity region calculated within the modified approach based on the assumption of similarity of inclusive hadron spectra. A satisfactory description is given of the NA61/SHINE data for the yield ratios K+/π+ and K−/π− as a function of √(s) in pp and BeBe collisions. Calculations of antiparticle-to-particle yield ratios ( p̅/ . -0em p , d̅/ . -0em d , He^3/ . -0emHe^3 ) in proton–proton and nucleus–nucleus reactions are presented.

A review on the gluon transverse momentum dependent distribution (TMD) and its application to the analysis of the ep DIS at the HERA energies, hard and soft pp processes at LHC energies and mid-rapidity is presented.

The article presents a review of the results of studies of the unstable states in the relativistic dissociation of nuclei 10B, 11,12C, 16O, 22Ne, 28Si, 84Kr, and 197Au in the energy range from hundreds of MeV/nucleon to several tens of GeV/nucleon using the nuclear track method. A systematic study of the fragmentation of incident nuclei with multiple production of the lightest fragments of He and H made it possible to study the dynamics of the manifestation of unstable nuclear states of 8Be, the Hoyle state, and the 4α-particle state of the 16O nucleus above the threshold in the relativistic dissociation of nuclei thanks to precision measurements of fragment outgoing angles. It is shown that, to reconstruct the relativistic decays of unstable nuclei in a nuclear photographic emulsion, it is sufficient to determine the invariant mass of the system of He and H fragments in the approximation of conservation of momentum per nucleon of the parent nucleus. This approach makes it possible to search for more complex nuclear states. An indication was obtained of an increase in the probability of detecting 8Be with an increase in the number of relativistic α particles in the event.

Prospects of the BECQUEREL experiment devoted to studying, within the relativistic approach, problems of nuclear-cluster physics are discussed. The nuclear track emulsion method used in the present study permits fully investigating relativistic final states in the fragmentation of nuclei. The present study focuses on the dynamics of the formation of a ^8 Be nucleus and the Hoyle state, as well as on searches for the 4 α condensate decaying through them. The development of analysis of exposure to ^84 Kr nuclei at an energy of 950 MeV per nucleon is described in this context. The status of searches for the isobar analog state of the ^13 N nucleus in the fragmentation of ^14 N nuclei at an energy of 2 GeV per nucleon is presented as a continuation of studies of light nuclei.

The article presents a review of studying unstable states in the relativistic dissociation of nuclei ^10B, ^11,12C, ^16O, ^22Ne, ^28Si, ^84Kr and ^197Au in the energy range from hundreds of MeV/nucleon to several tens of GeV/nucleon using the nuclear track emulsion method. A systematic study of the fragmentation of incident nuclei with multiple formation of the lightest fragments of He and H. This made it possible to study the dynamics of unstable nuclear states of ^8Be, the Hoyle state and the 4α-particle state of the ^16O nucleus above the threshold in the relativistic dissociation of nuclei due to precision measurements of fragment emission angles. It is shown that to reconstruct the relativistic decays of unstable nuclei in a nuclear track emulsion, it is sufficient to determine the invariant mass of the system of He and H fragments in the approximation of conservation of momentum per nucleon of the parent nucleus. This approach allows one to search for more complex nuclear states. An indication has been obtained of growing probability to detect ^8Be with increasing the number of relativistic α particles in the event.

—The paper presents the upgrade project of the Hyperon-M experiment in the positive beam line of the U-70 accelerator complex in Protvino to study hadron-nuclear interaction mechanisms. It is proposed that the setup be upgraded to study the excited states of secondary nuclei formed by different types of primary hadron–nuclear interaction using precision nuclear gamma-ray spectroscopy. This could open a new direction of the nuclear physics at the junction with the physics of elementary particles at intermediate energies.

The analysis of amplitude spectra from a thin polystyrene-based scintillation counter on muon-enriched and hadron beams of channel 18 of the U-70 accelerator complex in Protvino has been presented. On the basis of statistics of 150 million events on the Hyperon-M setup, the contribution of the 3α -fragmentation processes are highlighted and the cross sections of these processes on hadron and pion beams with a momentum of 7 GeV/ c have been measured. In the future, the obtained result may be of interest for the method of analyzing the age of gas fields based on the concentration of helium in natural gas, the formation of which is possible in the reaction of 3α fragmentation of carbon nuclei in μ^12C interactions induced by high-energy cosmic muons.

Studies at the Nuclotron in JINR indicate the presence of a previously unknown resonance-like structure in the two-photon mass spectrum in the region of 300−400 MeV/c2, observed in nucleus-nucleus interactions. The goal of this work is to search for such structures in the two-photon mass spectrum in meson-nuclear interactions at a momentum of 7 GeV/c at the Hyperon-M experiment of the U-70 accelerator complex. An upper limit has been established on the ratio of the cross section for the formation of unknown resonance structures to the cross section for the production of η-meson ρ(R→2γ/η→2γ) < 3.2 × 10–3 at the 95

The first results on analysis of determination of the contribution of decays of unstable 8 Be and 9 B nuclei and the Hoyle 3α-state into the dissociation of 14 N → 3He (+H) are presented. Layers of nuclear track emulsion longitudinally exposed to 2.9 A GeV/ с 14 N nuclei at the JINR Nuclotron are used as the research material. Under the assumption that He and H fragments preserve momentum per nucleon of the primary nucleus, these unstable states are identified by the minimum invariant mass calculated using fragment emission angles.

This article describes calculations of the yield ratio of anti-particles to the yield of particles ( $$\bar {p}$$ /p, $$\bar {d}$$ /d, $$\overline {^{3}{\text{He}}} $$ /3He) in proton–proton and nuclear–nuclear interactions using the self-similarity parameter in the central rapidity region. The used approach is based on the study of relativistic nuclear interactions in the four-velocity space. The results of the calculations are compared with the existing experimental data in a wide center-of-mass energy range (SPS, RHIC, LHC). Within this approach the inclusive spectra of pions and kaons and ratios of their yields in pp collisions have been successfully described earlier.

The inclusive spectra of pions and kaons produced in $Be Be$ collisions as functions of their transverse momentum $p_t$ at mid-rapidity are calculated within the self-similarity approach. A satisfactory description of NA61/SHINE data on these spectra and the ratio of $K^\pm$ to $\pi^\pm$ meson production cross sections in $Be Be$ collisions as a function of $\sqrt{s}$ are presented. The similarity of these observables to the ones for $pp$ collisions at mid-rapidity and in the wide range of initial energies is illustrated.

A calculation of the inclusive spectra of pions and kaons produced in pp collisions as functions of their transverse momentum $$p_T$$ at mid-rapidity is presented within the self-similarity approach. A satisfactory description of the data within a wide range of initial energies is presented. We focus mainly on the ratio of cross-sections of $$K^\pm $$ to $$\pi ^\pm $$ mesons produced in pp collisions as a function of $$\sqrt{s}$$ . A fast rise of this ratio, when the initial energy increases starting from the kaon production threshold up to $$\sqrt{s}\simeq $$ 20–30 GeV, is revealed together with its very slow increase up to LHC energies. The energy dependence of this ratio is due to the conservation laws of four-momenta and quantum numbers of the initial and produced hadrons. The more or less satisfactory agreement of these ratios with NA61/SHINE, RHIC and LHC data is demonstrated.

Experiments in preparation for search for uranium ternary fission by means of nuclear track emulsion are summarized. The study will be focused on the possible involvement of the unstable nucleus ${}^{8}$Be in the suggested scenario of the collinear tri-partition in the fission.

In the events of peripheral dissociation of relativistic nuclei in the nuclear track emulsion, it is possible to study the emerging ensembles of He and H nuclei, including those from decays of unstable 8Be and 9B nuclei, as well as the Hoyle state. These extremely short-lived states are identified by invariant masses calculated from the angles in 2α-pairs, 2αp- and 3α-triplets in the approximation of conservation of momentum per nucleon of the primary nucleus. In the same approach, it is possible to search for more complex states. This paper explores the correlation between the formation of 8Be nuclei and the multiplicity of accompanying α-particles in the dissociation of relativistic 16O, 22Ne, 28Si, and 197Au nuclei. On the above basis, estimates of this correlation are presented for the unstable 9B nucleus and the Hoyle state. The enhancement in the 8Be contribution to dissociation with the α-particle multiplicity has been found. Decays of 9B nuclei and Hoyle states follow the same trend.