[en] The spectrometer for the measurement energy of the prompt gamma rays from the reactions of inelastic scattering and radiation capture of neutrons are described. The timing selection prompt gamma-rays escaped from sample was used to decrease background. The measurement have been made of the differential cross sections of gamma ray production due to neutron interaction with the sample of silicon for incident neutron energy 14,1 MeV. Data were obtained using germanium-litium detector positioned at 70 deg and 90 deg with respect to the incident neutron beam. The correction factor of incident neutron attenuation and multiscattering and of gamma rays attenuation in sample were calculated by analytic method. The gamma ray production cross section for ten discrete levels excited by ²⁸Si(n,xγ) reactions have been evaluated. 7 refs.; 4 figs.; 1 tab

[en] The time-of-flight method was applied to measure spectrum of inelastically scattered neutrons in coincidence with 0.845 MeV γ-quanta at initial energy of neutrons equal to 14.1 MeV. Corrections necessary for processing experimental results and obtaining neutron from the reaction ⁵⁶(n,n'γ)⁵⁶Fe are analyzed

[en] The logics of organization of amplitude and time ''windows'' in the spectrometer for measuring neutron spectra and γ-quanta from the n(n, n'γ) reaction is described. The specific feature of the system is assignment of amplitude ''windows'' by digital method. Principle electronic device circuits description of their performance and spectra obtained with their assistance are shown

[en] Energy spectra of neutrons inelastically scattered on iron nuclei have been obtained for six scattering angles of 45 deg, 60 deg, 75 deg, 90 deg, 120 deg, 150 deg. The measurements were made by the time-of-flight method, the initial neutron energy being 14.3 MeV, the resolution not less than 1.2 ns/m. Such a resolution made it possible to discriminate the excitation level 3^-, Q=4.5 MeV in Fe. Differential cross sections of excitation for this level are obtained. Differential cross sections for different energy ranges are given. It is shown that the neutron spectrum may be presented in the form of a sum of the evaporating maxwellian part and the contribution of the direct inelastic scattering processes, the concept on the preequilibrium state of a nucleus being neglected. The description of doubly differential cross sections of direct processes by means of transition amplitudes, calculated in the Born approximation in the framework of the Butler scheme, agrees well with the experimental data when choosing a sufficiently wide range of the emitting neutron energy averaging. A more detailed description provides a calculation in the framework of the distorted wave method and there appears a possibility of predicting the peaks induced by separate transitions on the spectra of inelastically scattered neutrons

[en] A neutron detector is described with a γ-ray compensation feature for measuring neutron spectra by the neutron transit time method. The detector has been developed on the basis of a photomultiplier and a stilbene crystal employed to reduce the photomultiplier operating voltage. The use of γ-ray compensation improves the effect/background ratio by 3-5 times as large in the secondary neutron energy range of 1-10 MeV. The principle detector characteristics are considered, e.g. efficiency, resolution time, and γ-ray compensation. The method for measuring the principle detector parameters is described

[en] Comparative analysis of advantages and short-comings of the initial (time-of-flight base is 2.4 m) and modified (time of flight base is 7 m) geometries of experiments on measuring the spectra of neutron inelastic scattering on nuclei conducted by meas of the time-of-flight spectrometer is carried out. The spectra of neutrons scattering on iron, hydrogen and carbon nuclei at the angle of scattering equal to 60 deg and that for scattering on niobium at scattering angles equal to 45, 60, 90, 120 and 135 deg are measured. The spectrometer is designed on the base of the KG-0.3 cascade generator operating in a pulse mode. The neutrons from the T(d, n)⁴He reaction are produced under the action of deuteron pulses with duration of about 2.5 ns and the energy of 25O keV on the solid tritium-scandium target placed in the thin-wall stainless steel target holder with air cooling. The pulse frequency is 1.25 MHz. The neutron detector is the NE-218 liquid scintillator 100 mm in-diameter and 50 mm thick with the Philips XP-2041 photomultiplier. The n-j-compensation circuit is used in the detector. It is conclUded that the spectrometer time-of-flight base increase permits to improve its time resolution up to 0.6 ns/m

[en] Data on measuring the spectra of neutron emission from ⁹³Nb nuclei and (n, 2n) reaction cross sections are presented. Measurements were conducted by the time-of-flight method at 14MeV initial neutron energy. Spectra of neutrons scattered at 30, 45, 60, 75, 90, 105, 120 and 135 deg angles were measured. The primary neutron spectrum was calculated and then subtracted from the experimental total spectrum in order to obtain the secondary neutron spectrum. Calculations were conducted in two versions according to SMT-80 and STAPRE programs. The obtained values of the (n, 2n) reaction cross section differ slightly and equal 1347-1375 mb. It is concluded that the values obtained agree satisfactorily with those calculated earlier

No abstract available

[en] Spectra of inelastically scattered neutrons on niobium nuclei at 30, 45, 60, 75, 90, 120 and 135 deg angles were measured for 14.3 MeV neutron initial energy. The integral energy spectrum of neutron emission was obtained. Theoretical analysis of obtained spectrum was made. Spectra of the first and the second neutrons were separated out of the total spectrum and the (n, 2n) reaction cross-section was calculated

[en] The differential cross section of neutron emission in the ⁵⁶Fe(n,n'γ) reaction has been measured for 14.1 MeV. The neutron spectra have been measured by the time-of-flight method in coincidence with γ rays of selected energy. The experimental setup, experimental technique, and method of data analysis are described. The effects of energy resolution and multiple interactions in the sample on the accuracy of the data have been studied. Theoretical calculations of neutron spectra from the ⁵⁶Fe(n,n'γ) reactions were carried out in the Hauser-Feshbach model including the emission of neutrons and γ rays in the pre-equilibrium stage. The mean radiative width of the excited ⁵⁶Fe states for energies exceeding the neutron binding energy was found:<Γ/sub γ/> = 1.5 +- 1 eV. It is shown that the observed spectra can be interpreted without bringing in the Fe (n,γn') reaction