Download or read book Prompt Fission Neutron Spectra written by International Atomic Energy Agency and published by . This book was released on 1972 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Prompt Fission Neutron Spectra of N 235U Above the n Nf Fission Threshold Supported by National Natural Science Foundation of China 11205246 91126010 U1230127 91226102 IAEA CRP 15905 and Defense Industrial Technology Development Program B0120110034 written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Calculations of prompt fission neutron spectra (PFNS) from the 235 U(n, f) reaction were performed with a semi-empirical method for E n = 7.0 and 14.7 MeV neutron energies. The total PFNS were obtained as a superposition of (n, xnf) pre-fission neutron spectra and post-fission spectra of neutrons which were evaporated from fission fragments, and these two kinds of spectra were taken as an expression of the evaporation spectrum. The contributions of (n, xnf) fission neutron spectra on the calculated PFNS were discussed. The results show that emission of one or two neutrons in the (n, nf) or (n, 2nf) reactions influences the PFNS shape, and the neutron spectra of the (n, xnf) fission-channel are soft compared with the neutron spectra of the (n, f) fission channel. In addition, analysis of the multiple-chance fission component showed that second-chance fission dominates the PFNS with an incident neutron energy of 14.7 MeV whereas first-chance fission dominates the 7 MeV case.
Download or read book Fission Neutrons written by Nikolay Kornilov and published by Springer. This book was released on 2014-07-25 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although the fission of heavy nuclei was discovered over 75 years ago, many problems and questions still remain to be addressed and answered. The reader will be presented with an old, but persistent problem of this field: The contradiction between Prompt Fission Neutron (PFN) spectra measured with differential (microscopic) experiments and integral (macroscopic and benchmark) experiments (the Micro-Macro problem). The difference in average energy is rather small ~3% but it is stable and we cannot explain the difference due to experimental uncertainties. Can we measure the PFN spectrum with high accuracy? How may we compare results of different experiments to provide better accuracy? Are our traditional theoretical models correct? What can be done to solve the Micro-Macro problem in future? These questions are discussed in this monograph for the reader. The current work will be of interest to graduate students and researchers, particularly those working in nuclear and neutron physics.
Download or read book Prompt fission neutron Spectra of 233U 235U 239Pu and 24 Pu Relative to that of 252Cf 550 and 850 KeV written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The prompt-neutron-induced-fission spectra of 233U, 235U, 239Pu, and 24°Pu are measured relative to the prompt-spontaneous-fission-neutron spectrum of 252Cf. The fission of 233U, 235U, and 239Pu is induced by approx. = 550-keV neutrons, and that of 24°Pu, by approx. = 850-keV neutrons. The emitted fission neutrons are observed over the energy range less than or equal to 0.5 to 10.0 MeV by use of time-of-flight techniques. Analysis of the measured values indicates that the average-fission-neutron energies are -123 +- 30 (233U), -157 +- 24 (235U), -76 +- 29 (239Pu), and -46 +- 29 (24°Pu) keV relative to the energy for 252Cf. The experimental results are compared with those of ENDF/B-V, and a simple behavior of average-prompt-fission-neutron energies is suggested.
Download or read book Prompt Fission Neutron Spectra and Anti Nu P written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Methods used to obtain the evaluated prompt fisson neutron spectrum N(E) and the average prompt neutron multiplicity anti .nu./sub p/ are reviewed. The relative influence of experimental data; interpolated, extrapolated, and fitted experimental data; systematics; and nuclear theory are considered for the cases where (a) abundant experimental data exist, (b) some experimental data exist, and (c) no experimental data exist. The Maxwellian and Watt distributions, and the determination of the parameters of these distributions by data fitting, are described and compared to recent new theoretical work on the calculation of N(E). Similarly, various expressions for anti .gamma./sub p/ that have been obtained by data fitting and systematics are described and compared to recent new theoretical work. Complications in the evaluation of N(E) and anti .gamma./sub p/ due to the onset of multiple-chance fission and the interrelationships between N(E), anti .gamma delta./sub p/ and the multiple-chance fission cross section are discussed using the example of the fission of 235U. Some statistics and comments are given on the evaluations of N(E) and anti .gamma./sub p/ contained in ENDF/B-V, and a number of concluding recommendations are made for future evaluation work.
Download or read book Prompt Fission Neutron Spectra written by and published by . This book was released on 1972 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recent Improvements in the Calculation of Prompt Fission Neutron Spectra written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Three tropics have been considered in the refinement and improvement of our original calculations of prompt fission neutron spectra. These are an improved calculation of the prompt fission neutron spectrum N(E) from the spontaneous fission of 252Cf, a complete calculation of the prompt fission neutron spectrum matrix N(E, E/sub n/) from the neutron-induced fission of 235U, at incident neutron energies ranging from 0 to 15 MeV, and an assessment of the scission neutron component of the prompt fission neutron spectrum. Preliminary results will be presented and compared with experimental measurements and an evaluation. A suggestion has been made for new integral cross-section measurements.
Download or read book Panel proceedings series written by Consultants' Meeting on Prompt Fission Neutron Spectra (1971, Vienna) and published by . This book was released on 1972 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Prompt Neutron Fission Spectrum Mean Energies for the Fissile Nuclides and 252Cf written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The international standard for a neutron spectrum is that produced from the spontaneous fission of 252Cf, while the thermal neutron induced fission neutron spectra for the four fissile nuclides, 233U, 235U, 239Pu, and 241Pu are of interest from the standpoint of nuclear reactors. The average neutron energies of these spectra are tabulated. The individual measurements are recorded with the neutron energy range measured, the method of detection as well as the average neutron energy for each author. Also tabulated are the measurements of the ratio of mean energies for pairs of fission neutron spectra. 75 refs., 9 tabs. (LEW).
Download or read book Prompt Fission Neutron Spectra and Average Prompt Neutron Multiplicities written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a new method for calculating the prompt fission neutron spectrum N(E) and average prompt neutron multiplicity anti nu/sub p/ as functions of the fissioning nucleus and its excitation energy. The method is based on standard nuclear evaporation theory and takes into account (1) the motion of the fission fragments, (2) the distribution of fission-fragment residual nuclear temperature, (3) the energy dependence of the cross section sigma/sub c/ for the inverse process of compound-nucleus formation, and (4) the possibility of multiple-chance fission. We use a triangular distribution in residual nuclear temperature based on the Fermi-gas model. This leads to closed expressions for N(E) and anti nu/sub p/ when sigma/sub c/ is assumed constant and readily computed quadratures when the energy dependence of sigma/sub c/ is determined from an optical model. Neutron spectra and average multiplicities calculated with an energy-dependent cross section agree well with experimental data for the neutron-induced fission of 235U and the spontaneous fission of 252Cf. For the latter case, there are some significant inconsistencies between the experimental spectra that need to be resolved. 29 references.
Download or read book New Calculation of Prompt Fission Neutron Spectra and Average Prompt Neutron Multiplicities written by David G. Madland and published by . This book was released on 1981 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Fission Neutron Spectra with High energy Activation Detectors written by J. A. Grundl and published by . This book was released on 1963 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Prompt Fission Neutron Spectra written by Międzynarodowa Agencja Energii Atomowej and published by . This book was released on 1972 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Calculation of Prompt Fission Neutron Spectra 0 53 MeV written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A new calculation of the prompt fission neutron spectrum N(E) is presented as a function of both the fissioning nucleus and its excitation energy. The calculation, based upon standard nuclear-evaporation theory, accounts for the physical effects of the distribution of fission-fragment residual nuclear temperature and the energy dependence of the cross section for the inverse process of compound-nucleus formation. With the use of a residual nuclear temperature distribution based upon the Fermi-gas model, calculations were performed for two different assumptions concerning the cross section for compound-nucleus formation. Use of a constant cross section leads to a closed expression for the neutron energy spectrum, while use of an energy-dependent cross section, calculated with the optical model, yields a numerical integration. Results obtained for the two assumptions agree well with experimental data, although there is a preference for the energy-dependent cross section calculation. 7 figures.
Download or read book Perspectives on Measurements of Prompt Fission Neutron Spectra for Fission Induced by Fast Neutrons written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Promt Fission Neutron Spectra written by and published by . This book was released on 1972 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Event by event Evaluation of the Prompt Fission Neutron Spectrum from 239Pu n F written by and published by . This book was released on 2011 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
