[en] The paper considers the possibilities of theoretical description of various neutron source characteristics on the example of a gas deuterium target. It has been shown, that with proper models adopted not only the first moments but the function of neutron flux energy distribution can be calculated with good accuracy. There is a review of experimental measurement methods for incident particle energies, mean neutrons energies and distribution functions. Attention is paid to the systematic disagreement between the experimental and theoretical neutron fluxes from the gas target. A monoenergetic neutron source is totally determined by a distribution function of the neutrons by the energy and the angle of escape Φ(Ε, θ). In many cases, when the value σ(Ε) investigated is independent on an angle and can be described by a linear function in the range of averaging it is enough just to take into account the first moment of distribution. For this purpose the following factors should be taken into account: 1. Space distribution of incident particles; 2. Energy losses in target materials, energy and angle straggling, surface inhomogenety. 3. Energy and reaction cross-section variation with on the angle of neutron escape. Some of the above factors are often ignored at neutron source calculation, which may result in systematic energy shifting, may alter the neutron flux dependence on a distance, etc. At the same time all the factors affecting Φ(Ε) are calculated with the sufficient accuracy. That is the consideration of theoretical models of calculation and experimental methods of neutron source characteristics measurement the present work is devoted to

[en] This review considers recent development of those techniques which are used for the utilization of DT-neutron generators usually not being a part of commercially delivered low voltage accelerators. Such techniques are needed for maintaining a high stability of operation, high quality of experiments, radiation protection and flux monitoring. Moreover, a few modern techniques for the utilization of neutron generators in nuclear data measurements are presented. (author)

[en] A multipurpose D+T neutron source, based on a 20 mA duoplasmatron ion source and a 300 kV/40 mA high voltage power supply, under construction at the Institute of Physics in Bratislava, is described. Its basic purpose is to produce intense and pulsed beams of 14 MeV neutrons. The intense section of the source is expected to produce continuously 10¹² ns^-1 with a rotating TiT target. The low current dc section is designed to produce continuously 10¹⁰ ns^-1 and the fast pulsed section will be capable of generating a compressible D⁺ ion beam of a length of 2 ns on a target spot with about 10³ neutrons per pulse. The source components are designed to give high reliability with little maintenance in order to minimize the radiation hazard in view of the extreme concentration of radioactive tritium. (author)

[en] The Associated Particle Technique (A.P.T.) had been used with neutrons from the D(d,n)³He and T(d,n)⁴He reactions to the absolute neutron detection efficiency of an 1.27x3.81cm² Stilbene scintillator as function of the light collection threshold and the neutron kinetic energy in the energy range 2/18 MeV. Thin Ti-T and home made deuterated polyethylene targets have been used. The A.P.T. chamber description, the measurements and the comparison with both analytical and Montecarlo (SAN-REMO code) calculations are reported. (author)

[en] Employing a direction-sensitive method of fission fragment detection in conjunction with neutron time-of-flight spectroscopy the energy and angular distribution of Cf fission neutrons has been measured. The correlation experiment and multi-parameter analysis is briefly described. We present first experimental data which are compared with statistical-model calculations in the framework of the complex cascade-evaporation model as well as an extended version of the generalized Madland-Nix model. (author)

[en] Simple analytical expressions are given for the calculation of the energy and angular distributions of neutrons emitted in the reactions ²H(d,n)³He and ³H(d,n)⁴He for the 20-500 keV deuteron energy range. The results obtained were compared with the measured and calculated thin and thick target energy and angular distributions of D+T neutrons at 75, 125, 150, 175 and 210 keV deuteron energies. The energy spread of D+T neutrons as functions of emission angle and deuteron energy is also given for thick TiT target. (author)

[en] By making use of the average cross section data (Mannhart's evaluation) for twenty-five reactions measured with the ²⁵²Cf spontaneous fission neutron source, its spectral shape was unfolded by NEUPAC. As a whole, the result agrees with the predicted ones by Madland and by Maerten and with the measured one by Poenitz and Tamura, but obviously differs from the Maxwellian spectrum with its average energy E_av=2.13 MeV. The influence of each cross section data to the shape of the unfolded spectrum was investigated. The ²⁵²Cf spectrum averaged cross sections for the above reactions were calculated by making use of energy dependent cross section data from ENDF/B-V (dosimetry file), JENDL-2 and internal library of NEUPAC and of six expressions of its spectral shape; (1) Maxwellian (E_av=2.13), (2) Madland's prediction, (3) Maerten's predictions (CEM and GMNM), (4) Gerasimenko's prediction, and (5) the spectrum unfolded by NEUPAC. By comparison of the calculated values with the measured ones, checked were the shape of the ²⁵²Cf fission neutron spectrum and the convergence between the measured and calculated cross section data. The average cross section data for the above reactions were tried to be plotted by the Horibe's empirical rule. Although the number of data is rather restricted, we can see good systematics for the (n,p), (n,α) and (n,2n) reactions similar to the case of the average cross sections to the ²³⁵U fission neutron spectrum. (author)

[en] This paper describes the development and standardization of the neutron fields simply manufactured for detector calibrations used for radiation control and environmental measurement. These fields are the following: (1) bare ²⁵²Cf fission field, (2) iron-moderated ²⁵²Cf field, (3) carbon-moderated ²⁵²Cf field, and (4) polyethylene-moderated ²⁵²Cf field. These fields are most suitable for calibrating the detectors used in and around nuclear and radiation facilities, since the fields are designed to simulate the typical neutron fields in and around the facilities. The direct neutron components of these fields have been standardized by the following two methods: (1) calculation by the ANISN code, and (2) measurements with and without a shadow shield, by detectors standardized in the national standard field at the Electrotechnical Laboratory (ETL). The neutron emission rates of the ²⁵²Cf source have been calibrated also at ETL. We have standardized the energy spectrum of direct component because of its independency to room size and peripheral structures; the accuracies have also been evaluated to be 20% below 100 keV, 15% at 1 MeV, and 50% above 5 MeV. The fields including room scattered components have also been characterized especially to calibrate the neutron detectors having high sensitivity to low energy room scattered neutrons; because large errors are included in the evaluation of low energy neutron components of the direct component field obtainable by shadow shield subtraction. These two kinds of fields can be situated on the secondary standard fields traceable directly to the primary national standard fields in ETL. (author)

[en] In these five years, the integral studies by D-T Neutron Source were carried out mainly to resolve the problems of fusion reactor neutronics. In addition to RTNS-I, OKTAVIAN, FNS and LOTUS were newly built for this area. Recent remarkable progresses in several fusion neutronics integral experiments are introduced here as well as to the neutron source properties and experimental methods. Those new machines have the very similar neutron intensity of 5x10¹²n/s order, and proved that their neutron intensities were enough to resolve the problems concerned with neutron spectrum. However, to measure the Tritium Breeding Ratio directly, it may be helpful for use to have higher intensity with nearly point-source characteristics. RTNS-II with the highest D-T neutron intensity of 6x10¹³n/s has mainly served for the fundamental studies of radiation damage, however, it has been sometimes very useful for fusion neutronics integral experiments. (author)

[en] The research reactor is now under construction at the Leningrad Institute of Nuclear Physics, 45 km away from the city. The projected power of the reactor is 100 Mwt. The reactor will be used for physical investigations with external neutron beams. The thermal neutron flux in the reflector is higher than 10¹⁵ neutrons/cm² sec and the flux in the usual water trap in the centre of the core is 4.10¹⁵ neutrons/cm² sec. Sources of cold and fast neutrons are designed in the reactor. Most of the experiments will be conducted on stationary neutron guides. (author)