Recent Advances in Modeling Fission Cross Sections Over Intermediate Structures
Recent Advances in Modeling Fission Cross Sections Over Intermediate Structures

Author:

Publisher:

Published: 2009

Total Pages:

ISBN-13:

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More accurate fission cross section calculations in presence of underlying intermediate structure are strongly desired. This paper recalls the common approximations used below the fission threshold and quantifies their impact. In particular, an exact expanded R-matrix Monte Carlo calculation of the intermediate structure, deeply mixed with the fluctuations of the class-I and II decay amplitudes, is shown. This paper also insists on the microscopic structure of the level densities as a function of the nucleus deformation and show preliminary neutron induced fission cross section calculations for 239Pu and 24°Pu using newly calculated combinatorial level densities. Comparisons with recent evaluated and measured fission cross sections are made.

Advances in Nuclear Physics
Advances in Nuclear Physics

Author: Michel Baranger

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 476

ISBN-13: 1461590418

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In the present volume and in the preceding one we have stretched our normal pattern of reviews by including articles of more major proportions than any we have published before. As a consequence each of these two vol umes contains only three review articles. From the beginning of this series it has been our aim, as editors, to achieve variation in the scope, style, and length of individual articles sufficient to match the needs of the individual topic, rather than to restrain the authors within rigid limits. We feel that the two major articles of Vols. 5 and 6 are entirely justified and do not repre sent unnecessary exuberance on the part of the authors. The article by Michaudon on fission is the first comprehensive account of the developments in this subject, which have placed it in the center of the stage of nuclear physics during the past few years. The discovery of fission isomerism and its dramatic manifestations in the intermediate structure of the neutron cross sections for fissionable isotopes are among the most im portant and interesting events to occur in nuclear physics. These events came as a surprise, and reaffirmed that the strength of nuclear physics lies in the combination of ingenious experiments with simple ideas.

Fission Theory
Fission Theory

Author:

Publisher:

Published: 1989

Total Pages:

ISBN-13:

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The development of fission reaction theory in relation to its predictive power in the calculation of neutron cross-sections is reviewed. The topics covered include the transition state spectrum and the channel theory; the discovery of complex topography in the fission barrier and the consequences of intermediate structure in fission cross-sections; the evidence of experimental data in parameterizing the fission barrier; and the role of other aspects of collective nuclear motion in controlling fission reaction rates. 51 refs., 6 figs.

Fission Cross Sections in the Intermediate Energy Region
Fission Cross Sections in the Intermediate Energy Region

Author:

Publisher:

Published: 1991

Total Pages: 11

ISBN-13:

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Until recently there has been very little cross section data for neutron-induced fission in the intermediate energy region, primarily because no suitable neutron source has existed. At Los Alamos, the WNR target-4 facility provides a high-intensity source of neutrons nearly ideal for fission measurements extending from a fraction of a MeV to several hundred MeV. This paper summarizes the status of fission cross section data in the intermediate energy range (En> 30 MeV) and presents our fission cross section data for 235U and 238U compared to intranuclear cascade and statistical model predictions.