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

Technical Report · Tue Sep 27 00:00:00 EDT 2016

DOI:https://doi.org/10.2172/1331468· OSTI ID:1331468

Casperson, R. J. ^[1]; Burke, J. T. ^[1]; Hughes, R. O. ^[1]; Akindele, O. A. ^[2]; Koglin, J. D. ^[1]; Wang, B. ^[1]; Tamashiro, A. ^[3]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. Univ. of California, Berkeley, CA (United States)
3. Oregon State Univ., Corvallis, OR (United States)

Directly measuring (n,2n) cross sections on short-lived actinides presents a number of experimental challenges. The surrogate reaction technique is an experimental method for measuring cross sections on short-­lived isotopes, and it provides a unique solution for measuring (n,2n) cross sections. This technique involves measuring a charged-­particle reaction cross section, where the reaction populates the same compound nucleus as the reaction of interest. 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. Advanced multiplicity analysis techniques have been developed for this work, which should allow for efficient analysis of ²⁴¹Pu(n,2n) and ²³⁹Pu(n,2n) cross section measurements

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC52-07NA27344
• OSTI ID: 1331468
• Report Number(s): LLNL-TR-703909; TRN: US1700500
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
NEUTRON REACTIONS
URANIUM 235 TARGET
NEUTRON DETECTORS
CROSS SECTIONS
NEUTRON DETECTION
ACTINIDES
SI SEMICONDUCTOR DETECTORS
EFFICIENCY
TELESCOPE COUNTERS
NEUTRONS
URANIUM 234
PLUTONIUM 241 TARGET
PLUTONIUM 240
PLUTONIUM 239 TARGET
PLUTONIUM 238
COMPOUND-NUCLEUS REACTIONS
MEASURING METHODS
ALPHA REACTIONS
INELASTIC SCATTERING