Numerical integration of detector response functions via Monte Carlo simulations

Kelly, K. J.; O’Donnell, J. M.; Gomez, J. A.; Taddeucci, T.N.; Devlin, M.; Haight, R. C.; White, Morgan Curtis; Mosby, S.; Neudecker, Denise; Buckner, Matthew; Wu, C. Y.; Lee, H.Y.

doi:10.1016/j.nima.2017.05.048

Cited by 16 publications

(7 citation statements)

References 21 publications

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“…Details of the Chi-Nu experimental setup and data analysis techniques can be found in Refs. [24,26,[28][29][30], and so only the essential details will be repeated here. The neutron spectra analyzed in this paper were measured with an array of 54 liquid scintillator detectors placed at angles corresponding to the surface of a hemisphere at a target-to-detector distance of ≈ 1 m with an actinide-containing parallel-plate avalanche counter target [31].…”

mentioning

confidence: 99%

Preequilibrium Asymmetries in the Pu239(n,f) Prompt Fission Neutron Spectrum

et al. 2019

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The physical properties of neutrons emitted from neutron-induced fission are fundamental to our understanding of nuclear fission. However, while state-of-the-art fission models still incorporate isotropic fission neutron spectra, it is believed that the pre-equilibrium pre-fission component of these spectra is strongly anisotropic. The lack of experimental guidance on this feature has not motivated incorporation of anisotropic neutron spectra in fission models, though any significant anisotropy would impact descriptions of a fissioning system. In the present work, an excess of counts at high energies in the fission neutron spectrum of 239 Pu is clearly observed and identified as an excess of the pre-equilibrium pre-fission distribution above the post-fission neutron spectrum. This excess is separated from the underlying post-fission neutron spectrum and its angular distribution is determined as a function in incident neutron energy and outgoing neutron detection angle. Comparison with neutron scattering models provides the first experimental evidence that the preequilibrium angular distribution is uncorrelated with the fission axis. The results presented here also impact the interpretation of several influential prompt fission neutron spectrum measurements.

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confidence: 99%

Preequilibrium Asymmetries in the Pu239(n,f) Prompt Fission Neutron Spectrum

et al. 2019

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“…1 of Ref. [7]). However, this assumption is incorrect for the majority of detected neutrons because it can be rare for a neutron to have exactly zero scatters between creation within the target and detection.…”

Section: The Chi-nu 6 Li-glass Detector Response Matrixmentioning

confidence: 88%

Measurements of the Prompt Fission Neutron Spectrum at LANSCE: The Chi-Nu Experiment

et al. 2018

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The goal of the Chi-Nu experiment at the Los Alamos Neutron Science Center is to measure the prompt fission neutron spectra from major actinides using a double time-of-flight method with a pulsed, white incoming neutron source. Fission events are detected with a parallel-plate avalanche counter and outgoing neutrons are detected with either a 6Li-glass or liquid scintillator detector array for low- or high-energy neutrons, respectively. A detector response matrix for the interaction of neutrons with the experimental environment for neutrons measured with the Chi-Nu 6Li-glass detector array has been calculated to obtain a full understanding of the measured Chi-Nu data and also to allow for nearly instantaneous production of simulated Chi-Nu data spectra. Prompt fission neutron spectra corresponding to 19 incoming neutron energy ranges from 0.7-20 MeV have been extracted using the ratio-of-ratios method with Chi-Nu 6Li-glass data on the neutron-induced fission of 235U.

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“…following references [9,43,52]. The key difference here is that the multiple-scattering and attenuation correction merge with the neutron-detection efficiency to an environmental detector-response matrix, R, of the TOF measurement, while the variable û encompasses all other corrections mentioned above and is not written out explicitly.…”

Section: Pfns Shape Measurementsmentioning

confidence: 99%

“…The background, b, can assume values at some E out that are even larger than the signal one wants to measure [9]. This is especially true at E out < 100 keV [13,38,42,52,66]. Background can arise from γs in γ-sensitive neutron detectors, beam contaminations (e.g., secondary-neutron group, protons or charged particles in the beam), wrap-around neutrons (dependent on spacing between source-neutron pulses), from pile-up of incident neutrons, room-return, random coincidences, α-particles from the sample, etc.…”

Section: Background Uncertaintiesmentioning

confidence: 99%

Templates of expected measurement uncertainties for prompt fission neutron spectra

Neudecker,

Devlin,

Haight

et al. 2023

EPJ Nuclear Sci. Technol.

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In this paper, we provide templates of uncertainty sources expected to appear for three measurement types of prompt fission neutron spectra (PFNS): (1) shape measurements, (2) clean-ratio shape, that is the monitor PFNS are measured in nearly exactly the same surrounding as the PFNS of interest, and (3) indirect ratios, where the detector efficiency is backed out from PFNS monitor measurements. Information is also listed that is needed to faithfully include PFNS in nuclear data evaluations to guide experimenters on how to best report data and metadata for their measurements. These templates also suggest a typical range of pertinent uncertainty values and their correlations in case realistic uncertainties cannot be estimated from information on the measurement itself. The templates were based on a literature review, information found in EXFOR for 252Cf, 235, 238U, and 239Pu PFNS, and enhanced by expertise from experimenters contributing to these PFNS templates.

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Numerical integration of detector response functions via Monte Carlo simulations

Cited by 16 publications

References 21 publications

Preequilibrium Asymmetries in the Pu239(n,f) Prompt Fission Neutron Spectrum

Preequilibrium Asymmetries in the Pu239(n,f) Prompt Fission Neutron Spectrum

Measurements of the Prompt Fission Neutron Spectrum at LANSCE: The Chi-Nu Experiment

Templates of expected measurement uncertainties for prompt fission neutron spectra

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