Download or read book Fission Fragment Angular Distribution and Fission Cross Section Validation written by Lou Sai Leong and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present knowledge of angular distributions of neutron-induced fission is limited to a maximal energy of 15 MeV, with large discrepancies around 14 MeV. Only 238U and 232Th have been investigated up to 100 MeV in a single experiment. The n_TOF Collaboration performed the fission cross section measurement of several actinides (232Th, 235U, 238U, 234U, 237Np) at the n_TOF facility using an experimental set-up made of Parallel Plate Avalanche Counters (PPAC), extending the energy domain of the incident neutron above hundreds of MeV. The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. I will show the methods we used to reconstruct the full angular resolution by the tracking of fission fragments. Below 10 MeV our results are consistent with existing data. For example in the case of 232Th, below 10 MeV the results show clearly the variation occurring at the first (1 MeV) and second (7 MeV) chance fission, corresponding to transition states of given J and K (total spin and its projection on the fission axis), and a much more accurate energy dependence at the 3rd chance threshold (14 MeV) has been obtained. In the spallation domain, above 30 MeV we confirm the high anisotropy revealed in 232Th by the single existing data set. I'll discuss the implications of this finding, related to the low anisotropy exhibited in proton-induced fission. I also explore the critical experiments which is valuable checks of nuclear data. The 237Np neutron-induced fission cross section has recently been measured in a large energy range (from eV to GeV) at the n TOF facility at CERN. When compared to previous measurements, the n TOF fission cross section appears to be higher by 5-7 % beyond the fission threshold. To check the relevance of n TOF data, we simulate a criticality experiment performed at Los Alamos with a 6 kg sphere of 237Np. This sphere was surrounded by enriched uranium 235U so as to approach criticality with fast neutrons. The simulation predicts a multiplication factor keff in better agreement with the experiment (the deviation of 750 pcm is reduced to 250 pcm) when we replace the ENDF/B- VII.0 evaluation of the 237Np fission cross section by the n TOF data. We also explore the hypothesis of deficiencies of the inelastic cross section in 235U which has been invoked by some authors to explain the deviation of 750 pcm. The large distortion that should be applied to the inelastic cross sections in order to reconcile the critical experiment with its simulation is incompatible with existing measurements. Also we show that the nubar of 237Np can hardly be incriminated because of the high accuracy of the existing data. Fission rate ratios or averaged fission cross sections measured in several fast neutron fields seem to give contradictory results on the validation of the 237Np cross section but at least one of the benchmark experiments, where the active deposits have been well calibrated for the number of atoms, favors the n TOF data set. These outcomes support the hypothesis of a higher fission cross section of 237Np.

Download or read book The Angular Distribution of Fission Fragments from the Fast Neutron induced Fission of U 234 written by Richard W. Lamphere and published by . This book was released on 1962 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fission Fragment Angular Distributions Measured with a Time Projection Chamber written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject is presented in a series of slides with the following organization: Introduction (What is anisotropy? Relevance (Theory and ratio cross section), Previous measurements); Experiment (Particle tracking in the fissionTPC, Neutron time of flight, Data analysis & uncertainty calculation, Preliminary result for 235U); and Future Work (Refine 235U result, Process 239Pu data).

Download or read book Channel Analysis of Fission written by John Archibald Wheeler and published by . This book was released on 1963 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976 with total page 1288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration and published by . This book was released on 1976 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration. Technical Information Center and published by . This book was released on 1976 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reactor Spectra Effects on Fission Fragment Cross Sections written by Charles Richard Greenhow and published by . This book was released on 1959 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics and Chemistry of Fission written by H. Märten and published by Nova Publishers. This book was released on 1992 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents: Fission Fragment Distributions: Experiment and Theory -- Fission Barriers, Fission Channels, Fission Valleys; Fragment Charge Distributions in Low Energy Fission; Double-Energy, Double-Velocity Measurement of Fission Fragments from Thermal Neutron Induced Fission; Odd-Even Neutron and Proton Effects in Low Energy Nuclear Fission; Energy Balance in MeV Neutron Induced Fission; Formation of the Fragment Mass and Energy Distributions in Fission of Nuclei Lighter than Radium; A New Approach to Determine Elemental Yield, Charge Polarisation and Odd-even Effects in Fission; Fundamental Fission Problems -- Dissipation and Friction in Nuclear Fission; Influence of Diabaticity on Fission Fragment Mass Asymmetry; Space Parity Violation in Nuclear Fission.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1971 with total page 1330 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Cross Sections and Technology written by Roald Amundsen Schrack and published by . This book was released on 1975 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Cross Sections and Technology written by Roald A. Schrack and published by . This book was released on 1975 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1974-03 with total page 1100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fission Fragment Angular Distributions Following Transfer Reactions for 232Th 16O written by and published by . This book was released on 1989 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fission Program at N TOF written by Laurent Tassan-Got and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its start in 2001 the n_TOF collaboration developed a measurement program on fission, in view of advanced fuels in new generation reactors. A special effort was made on measurement of cross sections of actinides, exploiting the peculiarity of the n_TOF neutron beam which spans a huge energy domain, from the thermal region up to GeV. Moreover fission fragment angular distributions have also been measured. An overview of the cross section results achieved with different detectors is presented, including a discussion of the 237Np case where discrepancies showed up between different detector systems. The results on the anisotropy of the fission fragments and its implication on the mechanism of neutron absorption, and in applications, are also shown.

Download or read book Angular Distributions from Heavy ion induced Fission written by Victor E. Viola and published by . This book was released on 1961 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: