Request ID | 44 | Type of the request | High Priority request | ||
---|---|---|---|---|---|
Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
93-NP-237 | (n,f) SIG | 200 keV-20 MeV | 2-3 | Y | |
Field | Subfield | Created date | Accepted date | Ongoing action | Archived Date |
Fission | fast reactors | 11-MAY-15 | 18-MAY-15 | 16-MAY-18 |
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Requester: Dr Fredrik TOVESSON at LANL, USA
Email: tovesson@lanl.gov
Project (context): Los Alamos National Laboratory
Impact:
Accuracy:
Justification document:
Comment from requester: The request is well motivated and of some concern also to reactor dosimetry when using spectral indices and/or reaction rates of 237Np fission chambers (IRDFF [7]).
Additional file attached: 1-s2.0-S0306454906000296-main.pdf
Review comment:
Entry Status:
Main recent references: Experiments Theory/Evaluation Validation
Uncertainties of 2-3%
There is a discrepancy of about 6-9% between a recent measurement performed by the n_TOF collaboration and ENDF/B-VII (C. Paradela et al. [3]).
The higher n_TOF values are supported by a validation exercise by Leong et al. [4].
A recent independent result in the energy range from 4.8 to 5.6 MeV yields cross sections that in function of energy first agree with ENDF/B-VII and then with the n_TOF result (M. Diakaki et al. [5]).
Independently an issue was recently found when cross sections for Pu-isotopes referred to the 238U(n,f) cross section were compared to the same cross sections referred to the 237Np(n,f) cross section in the same measurement arrangement (P. Salvador et al. [6]).
Completed (as of SG-C review of May 2018) - The request was related to a discrepancy between measurements performed at LANSCE [Tovesson:2007] and n_TOF [Paradela:2010]. New measurements using improved PPAC detectors have shown that the overestimation of the n_TOF data was caused by different roughness of the surface of the Np and U samples [Tassan-Got:2019].
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