[en] The characteristics of a ΔE–E telescope, which is planned to be used in the experimental setup focused on few-nucleon reactions, are studied. The required parameters of the ΔE–E telescope were determined on the basis of the numerical modeling of probable reactions. The telescope comprises a ΔE detector, which is a totally depleted surface-barrier silicon detector with a diameter of 8 mm and a thickness of ~24 μm, and an E detector based on LFS-8 crystals and a 16-element SiPM ARRAYC-30035-16P-PCB array. The telescope is designed, in particular, for coincidence detection of two charged particles emitted at close angles. This is made possible by the matrix structure of the E detector. The time resolution of the ΔE detector and the time and amplitude resolutions of all cells of the E detector were determined. The standard method of detection of two γ quanta from the beta decay of ²²Na was used to measure the time resolution. Time coincidences of signals from the ΔE detector and a neutron detector based on a liquid scintillator (EJ-301) with its FWHM no worse than 1 ns were obtained. Similar measurements for the E-detector cells revealed time (less than 0.6 ns) and amplitude (~15% at an energy of ~1 MeV) resolutions that satisfy the experimental requirements for particle sorting and determination of their energy. The intrinsic background of the E detector, which arises from the radioactivity of LFS-8 crystals, was measured. The relative number of events corresponding to simultaneous triggering of two or more E-detector cells irradiated with α particles from a ²²⁶Ra source was also determined. This value may help estimate the number of random coincidences in a real experiment.

[en] We consider a method of detecting the ionizing component of solar cosmic rays (SCRs) with energy from tens of MeV to tens of GeV by measuring the energy loss of SCR protons and light nuclei in scintillators and the multiplicity of the local neutron generation in a converter. Scintillation detectors based on stilbene, lithium glass, and solid-state photomultiplier tubes are capable of detecting fast neutrons with a temporal resolution of 10 ns and rejecting the gamma-ray background in the measuring system. The method will allow investigating the nucleon components of primary SCRs in circumterrestrial space.

[en] An analysis of the most recent data on the reaction nd → pnn revealed a serious discrepancy between theoretical predictions and cross sections measured for this reaction in various configurations where the role of neutron-neutron interactions is important. In view of this, it seems necessary both to develop theoretical approaches and to obtain new experimental data. For this purpose, a setup for studying the neutron-deuteron breakup reaction was created at the Institute for Nuclear Research on the basis of the neutron beam in the RADEX channel and deuterium targets. This facility makes it possible to perform experiments over a broad region of primary-neutron energies (10–60 MeV) and in various (final-state interaction, quasifree scattering, and spatial-star) configurations. Preliminary results of the respective experiment were obtained for configurations of final-state neutron-neutron interaction and quasifree neutron-neutron scattering

[en] The first results are obtained in a kinematically complete experiment devoted to measuring the n + d ^→ p + n + n reaction yield at energies in the range E_n = 40-60 MeV and various angles of divergence of two neutrons (Δθ = 4^o, 6^o, and 8^o) in the geometry of neutron-neutron final-state interaction. The ¹S₀ neutron-neutron scattering length a_nn is determined by comparing the experimental energy dependence of the reaction yield with the results of a simulation in the Watson-Migdal approximation, which depend on a_nn. For E_n = 40 MeV and Δθ = 6^o (the best statistics in the experiment), the value a_nn = -17.9 ± 1.0 fm was obtained. A further improvement of the experimental accuracy will make it possible to remove the existing disagreement of the results from different experiments.

[en] The characteristics of the extracted beam of thermal neutrons at the IN-LUE photoneutron source are investigated. A collimator with a cross-section diameter of 30 mm, located at an angle of 67° relative to the electron beam direction, was used to extract neutrons from the source. The neutron flux density as a function of the distance from the source center and the distribution of flux density over the distance from the collimator axis (beam profile) are obtained.

[en] The results of measuring the photofission reaction yield for actinide nuclei in the near-threshold energy region are presented. At the LUE-8-5 accelerator of the Institute for Nuclear Research of the Russian Academy of Sciences, the energy and time spectra of the delayed gamma quanta were obtained by irradiating fissile isotopes by bremsstrahlung photons. The conclusion is drawn about the possibility of identifying fissile isotopes by the behavior of the photofission cross section in the near-threshold region.

[en] New experimental results on the photoexcitation of Cd and In spin isomers by real and virtual photons (electrons) in the threshold energy region are presented. Measurements have been performed using the INR LUE-8 electron linac. The results are compared with theoretical calculations within the phenomenological models. There is a discrepancy between experimental data and theoretical calculations.

[en] An experimental setup for studying the reaction d + d → "2He + "2n is described, and the first preliminary results of measurements at a deuteron energy of 15 MeV are presented. The experiment was aimed at determining the energies of quasibound singlet states of two-nucleon systems (nn and pp), these energies being important features of nucleon–nucleon (NN) interaction. The measurements in question were performed at a deuteron beamfrom the U-120 cyclotron of the Skobeltsyn Institute ofNuclear Physics (Moscow State University). Two protons and one of the neutrons fromthe breakup of the dineutron system were detected in the experiment. A simulation of the reaction in question and preliminary experimental results reveal the possibility of determining the energy of quasibound singlet states on the basis of the form of the energy spectra of particles originating from their breakup

[en] Data obtained in recent years for the neutron–neutron scattering length in nd and dd breakup reactions are analyzed. Serious discrepancies between experimental data from different studies may be explained by the effect of three-nucleon forces depending on the velocity of separation of a neutron–neutron pair and a charged fragment. It is shown that the data under analysis can be approximated by a smooth curve representing the dependence of the scattering length on the parameter R, which determines the fragment-separation distance after a fixed time. This dependence makes it possible to obtain the scatteringlength value for R→∞—that is, in the absence of the effect of three-nucleon forces.