Measurement of Actinide Neutron Cross Sections
Measurement of Actinide Neutron Cross Sections

Author: Ka-Ngo Leung

Publisher:

Published: 2003

Total Pages:

ISBN-13:

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The maintenance of strong scientific expertise is criticalto the U.S. nuclear attribution community. It is particularly importantto train students in actinide chemistry and physics. Neutroncross-section data are vital components to strategies for detectingexplosives and fissile materials, and these measurements requireexpertise in chemical separations, actinide target preparation, nuclearspectroscopy, and analytical chemistry. At the University of California, Berkeley and the Lawrence Berkeley National Laboratory we have trainedstudents in actinide chemistry for many years. LBNL is a leader innuclear data and has published the Table of Isotopes for over 60 years. Recently, LBNL led an international collaboration to measure thermalneutron capture radiative cross sections and prepared the EvaluatedGamma-ray Activation File (EGAF) in collaboration with the IAEA. Thisfile of 35,000 prompt and delayed gamma ray cross-sections for allelements from Z=1-92 is essential for the neutron interrogation ofnuclear materials. LBNL has also developed new, high flux neutrongenerators and recently opened a 1010 n/s D+D neutron generatorexperimental facility.

Nuclear Fission and Neutron-Induced Fission Cross-Sections
Nuclear Fission and Neutron-Induced Fission Cross-Sections

Author: G. D. James

Publisher: Elsevier

Published: 2013-10-22

Total Pages: 294

ISBN-13: 1483189767

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Nuclear Fission and Neutron-Induced Fission Cross-Sections is the first volume in a series on Neutron Physics and Nuclear Data in Science and Technology. This volume serves the purpose of providing a thorough description of the many facets of neutron physics in different fields of nuclear applications. This book also attempts to bridge the communication gap between experts involved in the experimental and theoretical studies of nuclear properties and those involved in the technological applications of nuclear data. This publication will be invaluable to those interested in studying nuclear fission and neutron-induced fission cross-sections, as well as other relevant concepts.

Surrogate Measurements of Actinide (n, 2n) Cross Sections with NeutronSTARS.
Surrogate Measurements of Actinide (n, 2n) Cross Sections with NeutronSTARS.

Author:

Publisher:

Published: 2016

Total Pages: 21

ISBN-13:

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Directly measuring (n,2n) cross sections on short-lived actinides presents a number of experimental challenges: scattered beam can produce neutron backgrounds in the detectors, fission can produce a substantial neutron background, and created a target with a short-lived isotope can be extremely difficult. To perform these surrogate (n,2n) cross section measurements, a silicon telescope array has been placed along a beam line at the Texas A & M University Cyclotron Institute, which is surrounded by a large tank of Gadolinium-doped liquid scintillator, which acts as a neutron detector. The combination of the charge-particle and neutron-detector arrays is referred to as NeutronSTARS. In the analysis procedure for calculating the (n,2n) cross section, the neutron detection efficiency and time structure plays an important role. Due to the lack of availability of isotropic, mono-energetic neutron sources, modeling is an important component in establishing this efficiency and time structure. This report describes the NeutronSTARS array, which was designed and commissioned during this project. It also describes the surrogate reaction technique, specifically referencing a 235U(n,2n) commissioning measurement that was fielded during the past year.

Actinide Neutron-induced Fission Cross Section Measurements at LANSCE.
Actinide Neutron-induced Fission Cross Section Measurements at LANSCE.

Author:

Publisher:

Published: 2010

Total Pages:

ISBN-13:

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Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications in a wide energy range from sub-thermal energies up to 200 MeV. A parallel-plate ionization chamber are used to measure fission cross sections ratios relative to the 235U standard while incident neutron energies are determined using the time-of-flight method. Recent measurements include the {sup 233,238}U, 239−242Pu and 243Am neutron-induced fission cross sections. Obtained data are presented in comparison with ex isting evaluations and previous data.

Actinide Targets for Neutron Cross Section Measurements (C).
Actinide Targets for Neutron Cross Section Measurements (C).

Author:

Publisher:

Published: 2006

Total Pages:

ISBN-13:

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The Advanced Fuel Cycle Initiative (AFCI) and the Generation IV Reactor Initiative have demonstrated a lack of detailed neutron cross-sections for certain "minor" actinides, those other than the most common (235U, 238U, and 239Pu). For some closed-fuel-cycle reactor designs more than 50% of reactivity will, at some point, be derived from "minor" actinides that currently have poorly known (n, g) and (n, f) cross sections. A program of measurements under AFCI has begun to correct this. One of the initial hurdles has been to produce well-characterized, highly isotopically enriched, and chemically pure actinide targets on thin backings. Using a combination of resurrected techniques and new developments, we have made a series of targets including highly enriched 240Pu, and 242Pu. Thus far, we have electrodeposited these actinide targets. In the future, we plan to study reductive distillation to achieve homogeneous, adherent targets on thin metal foils and polymer backings. As we move forward, separated isotopes become scarcer, and safety concerns become greater. The chemical purification and electodeposition techniques will be described.

Actinide Targets for Neutron Cross Section Measurements
Actinide Targets for Neutron Cross Section Measurements

Author: John D. Baker

Publisher:

Published: 2006

Total Pages:

ISBN-13:

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The Advanced Fuel Cycle Initiative (AFCI) and the Generation IV Reactor Initiative have demonstrated a lack of detailed neutron cross-sections for certain "minor" actinides, those other than the most common (235U, 238U, and 239Pu). For some closed-fuel-cycle reactor designs more than 50% of reactivity will, at some point, be derived from "minor" actinides that currently have poorly known or in some cases not measured (n,?) and (n, f) cross sections. A program of measurements under AFCI has begun to correct this. One of the initial hurdles has been to produce well-characterized, highly isotopically enriched, and chemically pure actinide targets on thin backings. Using a combination of resurrected techniques and new developments, we have made a series of targets including highly enriched 239Pu, 240Pu, and 242Pu. Thus far, we have electrodeposited these actinide targets. In the future, we plan to study reductive distillation to achieve homogeneous, adherent targets on thin metal foils and polymer backings. As we move forward, separated isotopes become scarcer, and safety concerns become greater. The chemical purification and electodeposition techniques will be described.

Fission Cross Section Measurements of Actinides at LANSCE.
Fission Cross Section Measurements of Actinides at LANSCE.

Author:

Publisher:

Published: 2010

Total Pages:

ISBN-13:

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Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications. By combining measurement at two LANSCE facilities, Lujan Center and the Weapons Neutron Research center (WNR), differential cross sections can be measured from sub-thermal energies up to 200 MeV. Incident neutron energies are determined using the time-of-flight method, and parallel-plate ionization chambers are used to measure fission cross sections relative to the 235U standard. Recent measurements include the {sup 233,238}U, {sup 239,242}Pu and 243Am neutron-induced fission cross sections. In this paper preliminary results for cross section data of 243Am and 233U will be presented.