Measurement of the 239Pu(n,f)/235U(n,f) Cross-Section Ratio with the NIFFTE fission Time Projection Chamber

Snyder, L.; Anastasiou, M.; Bowden, N. S.; Bundgaard, J.; Casperson, R. J.; Cebra, D.; Classen, T.; Dongwi, D.H.; Fotiades, N.; Gearhart, J.; Geppert-Kleinrath, V.; Greife, U.; Hagmann, C.; Heffner, M.; Hensle, D.; Higgins, Dan; Isenhower, L.; Kazkaz, K.; Kemnitz, A.; King, J.; Klay, J. L.; Latta, J.; Leal-Cindoncha, E; Loveland, W.; Magee, J. A.; Manning, B.; Mendenhall, P; Monterial, Mateusz; Mosby, S.; Neudecker, Denise; Prokop, C. J.; Sangiorgio, S.; Schmitt, K. T.; Seilhan, B.; Tôvesson, F.; Towell, R. S.; Walsh, N.; Watson, T. S.; Yao, L.; Younes, W.

doi:10.1016/j.nds.2021.11.001

Cited by 15 publications

(15 citation statements)

References 41 publications

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“…The constant bias at about 2% is clearly visible in the energy range 0.2-15 MeV and has an even larger spread above 15 MeV. The authors of [16] provided a very detailed and deep analysis of the modeling of their experiment (experimental details, data reduction procedure, uncertainties of different parameters and so on) but at present could not explain the existing bias, which can be treated as SDF. From our point of view, it is premature to assign the SDF to this measurement, especially taking into account that the reaction rate ratios measured in clean benchmarks show better consistency with the NIFFTE results.…”

Section: Sdf In Fission Cross Section Ratio Measurementsmentioning

confidence: 99%

“…The results of the absolute ratio of 239 Pu(n,f) to 235 U(n,f) cross section measurements are shown in Figure 11. The data were taken from [16].…”

Section: Sdf In Fission Cross Section Ratio Measurementsmentioning

confidence: 99%

“…The authors of [16] came to the conclusion that the difference in 2% absolute normalization with the ENDF/B-VIII.0 [20] evaluation based on its turn on neutron standards evaluation [2] is too large to be ignored. The large non-uniformity and mass value of the 239 Pu sample, which can degrade with time, are the largest concern.…”

Section: Sdf In Fission Cross Section Ratio Measurementsmentioning

confidence: 99%

“…From our point of view, it is premature to assign the SDF to this measurement, especially taking into account that the reaction rate ratios measured in clean benchmarks show better consistency with the NIFFTE results. 239 Pu(n,f)/ 235 U(n,f) cross section ratio measured with a fission TPC [16] in comparison with the data [17][18][19] and the results of the GMA fit (solid line) with fission TPC data added to the standard (old) database.…”

Section: Sdf In Fission Cross Section Ratio Measurementsmentioning

confidence: 99%

“…Figure11.239 Pu(n,f)/ 235 U(n,f) cross section ratio measured with a fission TPC[16] in comparison with the data[17][18][19] and the results of the GMA fit (solid line) with fission TPC data added to the standard (old) database.…”

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confidence: 99%

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Systematic Distortion Factor and Unrecognized Source of Uncertainties in Nuclear Data Measurements and Evaluations

Корнилов

Pronyaev²,

Grimes

2021

Metrology

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Each experiment provides new information about the value of some physical quantity. However, not only measured values but also the uncertainties assigned to them are an important part of the results. The metrological guides provide recommendations for the presentation of the uncertainties of the measurement results: statistics and systematic components of the uncertainties should be explained, estimated, and presented separately as the results of the measurements. The experimental set-ups, the models of experiments for the derivation of physical values from primary measured quantities, are the product of human activity, making it a rather subjective field. The Systematic Distortion Factor (SDF) may exist in any experiment. It leads to the bias of the measured value from an unknown “true” value. The SDF appears as a real physical effect if it is not removed with additional measurements or analysis. For a set of measured data with the best evaluated true value, their differences beyond their uncertainties can be explained by the presence of Unrecognized Source of Uncertainties (USU) in these data. We can link the presence of USU in the data with the presence of SDF in the results of measurements. The paper demonstrates the existence of SDF in Prompt Fission Neutron Spectra (PFNS) measurements, measurements of fission cross sections, and measurements of Maxwellian spectrum averaged neutron capture cross sections for astrophysical applications. The paper discusses introducing and accounting for the USU in the data evaluation in cases when SDF cannot be eliminated. As an example, the model case of 238U(n,f)/235U(n,f) cross section ratio evaluation is demonstrated.

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Section: Sdf In Fission Cross Section Ratio Measurementsmentioning

confidence: 99%

“…The results of the absolute ratio of 239 Pu(n,f) to 235 U(n,f) cross section measurements are shown in Figure 11. The data were taken from [16].…”

Section: Sdf In Fission Cross Section Ratio Measurementsmentioning

confidence: 99%