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[en] Activity of the Lab. of radiations of Inst. of Nuclear Physics of National Nuclear Center is elucidated beginning from moment of it formation in 1956. It is marked, that there were first researches on gamma-quanta resonance scattering on nuclei. Researches were conducted on two trends: definition of life times of nuclei exited states and study of atomic interaction in condensed media under low energies. Simultaneously theoretical researches with purposes of interpretation of interaction cross sections for ultra- (10^-9< E<10^-7) and very cold 10^-7< E<10^-4) neutrons with substance have being carried out. Further stages of the Lab. activity are researches of exited states in (n,n'γ) reaction on fast neutron beam of the Wwr-K reactor. Joint study of life times and nuclear level spins, as well as insensitivities and angle distributions in one experiment have widen comprehensive study of nuclei structure and analysis of exited isotopes properties changes in dependence from neutrons number in nucleus. In last 2-3 years researches are conducting on (n,n'γ) reaction mechanism definition. Theoretical calculations of nucleus levels occupy ability in the reaction are worked out by optic-statistical compound-nucleus model in frame of Hauser-Feshbach-Malodour formalism

[en] Reflection and transmission of ultracold neutrons (UCN) in single- and two-layer material is considered a UCN propagation in one-dimensional steplike potential. Coefficients of reflection and transmission of single-layer specimens with surface oxide or sputtered layer are calculated. An example of possible application of UCN to determine substance composition of the surface and the length of coherent scattering

[en] The validity of rules determining the sign of change of the mean-square radius of nuclei excited to Moessbauer levels, formulated earlier for spherical and heavily deformed nuclei from data obtained in a simultaneous investigation of X-ray and Moessbauer spectra, is shown for specific cases. (Z.S.)

[en] The problem of ultracold neutrons (UCN) scattering on two-atom simple molecules has been considered. The rotational states structure of such molecules is well known and elastic and inelastic scattering separation can be easily performed. The results of UCN scattering cross section calculations on two-atom molecules and a perfect agreement between calculation and experimental total cross sections of UCN interaction with gases fully confirm the limiting conclusions of quantum mechanics pertaining to low velocities of the incident particle. UCN turned to be a handy instrument for experimental checking limiting conclusions of the quantum theory of scattering

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[en] Production of ultracold neutrons (UCN) is considered in the process of slowdown of reactor thermal neutrons on gas molecules of hydrogen, deuterium, tritium, nitrogen, oxygen against pressure and temperature of gas. It has been shown that UCN is produced mainly in the result of elastic scattering