![]() We describe each of the 14 sublibraries, focusing on neutron reactions. Cross Section Evaluation Working Group (CSEWG) in December 2006, contains data primarily for reactions with incident neutrons, protons, and photons on almost 400 isotopes, based on experimental data and theory predictions.The principal advances over the previous ENDF/B-VI library are the following: (1) New cross sections for U, Pu, Th, Np and Am actinide isotopes, with improved performance in integral validation criticality and neutron transmission benchmark tests (2) More precise standard cross sections for neutron reactions on H, 6Li, 10B, Au and for 235,238U fission, developed by a collaboration with the IAEA and the OECD/NEA Working Party on Evaluation Cooperation (WPEC) (3) Improved thermal neutron scattering (4) An extensive set of neutron cross sections on fission products developed through a WPEC collaboration (5) A large suite of photonuclear reactions (6) Extension of many neutron- and proton-induced evaluations up to 150 MeV (7) Many new light nucleus neutron and proton reactions (8) Post-fission beta-delayed photon decay spectra (9) New radioactive decay data (10) New methods for uncertainties and covariances, together with covariance evaluations for some sample cases and (11) New actinide fission energy deposition.The paper provides an overview of this library, consisting of 14 sublibraries in the same ENDF-6 format as the earlier ENDF/B-VI library. We describe the next generation general purpose Evaluated Nuclear Data File, ENDF/B-VII.0, of recommended nuclear data for advanced nuclear science and technology applications. Up to date publication reference details. In addition, peculiarities connected with pre-fission neutron emission are also discussed. The main attention is paid to the discussion of the evaluation procedure for two very important PFNS, 252Cf(sf) and 235U(th), and to the uncertainties for evaluated spectra and average energy of fission neutrons for these isotopes. However, the spectrum shape, predicted with these approaches and adjusted parameters, allows us to normalize experimental data, extrapolate the calculated PFNS to different input energies, and prepare the data library. All these approaches do not have any strong physical basis. Therefore, prompt fission neutron spectra (PFNS) are analyzed with semi-empirical formulas: Maxwellian distribution, single-Watt or two-Watt spectra approaches, “scale method,” and so on. All these peculiarities and possible methods of their investigations are discussed in this chapter.Ī rather realistic theoretical model has been in the hand of researchers since the 1950s, the so named “traditional assumptions” (see Introduction) however, the spectrum shape calculated on the basis of this assumption contradicts the experimental data, and this “physical” approach cannot help with the main request-to provide any useful function for data analysis. ![]() ![]() Some of them are as follows: different types of experiments (microscopic and macroscopic, differential and total FF-integrated experiments, selection of fission events according to neutron energy) and their possible systematical influence on the final result FF selection and fission fragment counting efficiency timing properties of the FF detector which is applied as a “stop” signal for the time of flight experiments neutron detector properties and how to estimate the efficiency of these detectors different components of correlated and uncorrelated backgrounds multiple neutron scattering on the detector’s environment and additional corrections for time resolution and bin width. Many factors or parameters of the experimental setup should be investigated in detail to reach high accuracy of PFNS. Each experiment has particular details which should be known in order to make proper corrections or avoid negative influence on the final results. A different experimental setup may be used for experimental investigation of PFNS. Due to the complicated nature of neutron emission in fission (several mechanisms of neutron emission are practically unknown, broad-mass and kinetic energy distribution, possible selection of fission fragment (FF) parameters, background neutrons), the prompt fission neutron spectrum (PFNS) measured in a particular experiment may be destroyed very much. ![]()
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