Total Cross Sections as a Surrogate for Neutron Capture

Total Cross Sections as a Surrogate for Neutron Capture

Author:

Publisher:

Published: 2014

Total Pages: 7

ISBN-13:

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There are many (n,?) cross sections of great interest to radiochemical diagnostics and to nuclear astrophysics which are beyond the reach of current measurement techniques, and likely to remain so for the foreseeable future. In contrast, total neutron cross sections currently are feasible for many of these nuclides and provide almost all the information needed to accurately calculate the (n,?) cross sections via the nuclear statistical model (NSM). I demonstrate this for the case of 151Sm; NSM calculations constrained using average resonance parameters obtained from total cross section measurements made in 1975, are in excellent agreement with recent 151Sm (n,?) measurements across a wide range of energy. Furthermore, I demonstrate through simulations that total cross section measurements can be made at the Manuel Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center for samples as small as 10?g. Samples of this size should be attainable for many nuclides of interest. Finally, I estimate that over half of the radionuclides identified 2̃0 years ago as having (n,?) cross sections of importance to s-process nucleosynthesis studies (24/43) and radiochemical diagnostics (11/19), almost none of which have been measured, can be constrained using this technique.


Total Cross Sections as a Surrogate for Neutron Capture

Total Cross Sections as a Surrogate for Neutron Capture

Author:

Publisher:

Published: 2014

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

There are many (n, [gamma]) cross sections of great interest to radiochemical diagnostics and to nuclear astrophysics which are beyond the reach of current measurement techniques, and likely to remain so for the foreseeable future. In contrast, total neutron cross sections currently are feasible for many of these nuclides and provide almost all the information needed to accurately calculate the (n, [gamma]) cross sections via the nuclear statistical model (NSM). I demonstrate this for the case of 151Sm; NSM calculations constrained using average resonance parameters obtained from total cross section measurements made in 1975, are in excellent agreement with recent 151Sm (n, [gamma]) measurements across a wide range of energy. Furthermore, I demonstrate through simulations that total cross section measurements can be made at the Manuel Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center for samples as small as 10[mu]g. Samples of this size should be attainable for many nuclides of interest. Finally, I estimate that over half of the radionuclides identified ~20 years ago as having (n, [gamma]) cross sections of importance to s-process nucleosynthesis studies (24/43) and radiochemical diagnostics (11/19), almost none of which have been measured, can be constrained using this technique.


Theoretical Challenges of Determining Low-Energy Neutron Capture Cross Sections Via the Surrogate Technique

Theoretical Challenges of Determining Low-Energy Neutron Capture Cross Sections Via the Surrogate Technique

Author: R. D. Hoffman

Publisher:

Published: 2004

Total Pages: 6

ISBN-13:

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Cross sections for radiative neutron capture on unstable nuclei at low energies are difficult to calculate with high precision, and can be impossible to measure directly. It is therefore important to explore alternative methods. The prospects of one such method, the Surrogate Nuclear Reaction Technique, is currently being investigated at Lawrence Livermore National Laboratory. The purpose of this paper is to outline the strategy for combining the results from a surrogate experiment with theoretical calculations in order to extract the desired cross section.