Journal ArticleDOI
Fluctuations of Nuclear Reaction Widths
Charles E. Porter,R. G. Thomas +1 more
TLDR
In this paper, the fluctuations of the neutron reduced widths from the resonance region of intermediate and heavy nuclei have been analyzed by a statistical procedure which is based on the method of maximum likelihood.Abstract:
The fluctuations of the neutron reduced widths from the resonance region of intermediate and heavy nuclei have been analyzed by a statistical procedure which is based on the method of maximum likelihood. It is found that a chi-squared distribution with one degree of freedom is quite consistent with the data while a chi-squared distribution with two degrees of freedom (an exponential distribution) is not. The former distribution corresponds to a Gaussian distribution for the reduced-width amplitude, and a plausibility argument is given for it which is based on the consideration of the matrix elements for neutron emission from the compound nucleus and of the central limit theorem of statistics. This argument also suggests that within the framework of the compound-nucleus theory all reduced-width amplitudes have Gaussian distributions, and that many of the distributions for the various channels may be independent. One consequence of the latter suggestion is that the total radiation width for a given spin state which is formed in neutron capture will be essentially constant, in agreement with some observations, because it is the sum of many partial radiation widths. The fluctuations of the provisional fission widths of ${\mathrm{U}}^{235}$ are best described by a chisquared distribution with about 2\textonehalf{} degrees of freedom, indicating that there are effectively only a few independently contributing fission channels.read more
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Journal ArticleDOI
Unified theory of nuclear reactions
TL;DR: In this article, a new formulation of the theory of nuclear reactions based on the properties of a generalized "optical" potential is presented, where the real and imaginary part of this potential satisfy a dispersion type relation while its poles give rise to resonances in nuclear reactions.
Journal ArticleDOI
ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology
Mark B. Chadwick,P. Obložinský,M.W. Herman,N.M. Greene,R.D. McKnight,David Livingstone Smith,Phillip G. Young,R. E. MacFarlane,Gerald M. Hale,S.C. Frankle,A.C. Kahler,Toshihiko Kawano,R. C. Little,D. G. Madland,Peter Möller,Russell D. Mosteller,Philip R. Page,Patrick Talou,Holly R. Trellue,Morgan C. White,William B. Wilson,R. Arcilla,C.L. Dunford,Said F. Mughabghab,Boris Pritychenko,D. Rochman,Alejandro Sonzogni,C.R. Lubitz,T.H. Trumbull,J.P. Weinman,David Brown,D.E. Cullen,David P. Heinrichs,D. P. McNabb,Herve Derrien,Michael E Dunn,Nancy M. Larson,Luiz C Leal,Allan D. Carlson,R.C. Block,J.B. Briggs,E.T. Cheng,H.C. Huria,M.L. Zerkle,K.S. Kozier,A. Courcelle,V.G. Pronyaev,S. C. van der Marck +47 more
TL;DR: The ENDF/B-VII.0 as discussed by the authors file contains data primarily for reactions with incident neutrons, protons, and photons on almost 400 isotopes, based on experimental data and theory predictions.
Journal ArticleDOI
RIPL – Reference Input Parameter Library for Calculation of Nuclear Reactions and Nuclear Data Evaluations
Roberto Capote,M.W. Herman,M.W. Herman,P. Obložinský,P. Obložinský,Phillip G. Young,Stéphane Goriely,Tamás Belgya,A.V. Ignatyuk,Arjan J. Koning,Stéphane Hilaire,Vladimir Plujko,Marilena Avrigeanu,O. Bersillon,Mark B. Chadwick,Tokio Fukahori,Zhigang Ge,Yinlu Han,S. Kailas,J. Kopecky,V.M. Maslov,G Reffo,M. Sin,E. Sh. Soukhovitskii,Patrick Talou +24 more
TL;DR: The Reference Input Parameter Library (RIPL-3) as mentioned in this paper is a library of validated nuclear-model input parameters, referred to as the RIPL-2 library, which has been used extensively in the development and use of nuclear reaction modelling.
Journal ArticleDOI
Characterizing Quantum Supremacy in Near-Term Devices
Sergio Boixo,Sergei V. Isakov,Vadim Smelyanskiy,Ryan Babbush,Nan Ding,Zhang Jiang,Michael J. Bremner,John M. Martinis,John M. Martinis,Hartmut Neven +9 more
TL;DR: In this article, the authors study the task of sampling from the output distributions of (pseudo-)random quantum circuits, a natural task for benchmarking quantum computers, and show that this sampling task must take exponential time in a classical computer.
Journal ArticleDOI
The statistical model and nuclear level densities
TL;DR: In this article, a treatment from a theoretical point of view is given for different aspects of the statistical model and nuclear level densities. But the authors do not consider the nuclear phase transition.