18 research outputs found

    ENDF-6 compatible evaluation of neutron induced reaction cross sections for 182,183,184,186W

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    An ENDF-6 compatible evaluation for neutron induced reactions in the resonance region has been completed for 182,183,184,186W. The parameters are the result of an analysis of experimental data available in the literature together with a parameter adjustment on transmission and capture data obtained at the time-of-flight facility GELINA. Complete evaluated data files in ENDF-6 format have been produced by joining the evaluations in the resonance region with corresponding files from the JEFF-32T1 and ENDF/B-VII.1 library. The evaluated files have been processed with the latest updates of NJOY.99 to test their format and application consistency as well as to produce a continuous-energy data library in ACE format for use in Monte Carlo codes. The evaluated files will be implemented in the next release of the JEFF-3 library which is maintained by the Nuclear Energy Agency of the OECD. The evaluated files will be implemented in the next release of the JEFF-3 library which is maintained by the Nuclear Energy Agency of the OECD.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

    Evaluation of neutron induced reaction cross sections in the resolved and unresolved resonance region at EC-JRC-IRMM

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    Recent efforts made at the EC-JRC-IRMM to produce evaluated cross section data files for neutron induced reactions are described as well as the methodology applied in both the resolved and unresolved resonance. For the resolved resonance region the paper focuses on a recent evaluation of isotopes present in natural cadmium. For the unresolved resonance region results for gold are presented.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

    Resonance Analysis in the Region of Unresolved Resonance

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    The independent analysis of new experimental data for 232Th cross sections in the unresolved region performed on the basis of the existing scheme and method of evaluation confirm the previously obtained average resonance parameters. The method of statistical modeling of the resonant cross-section structure in the unresolved resonance region, proposed and developed earlier by introducing the characteristic function of R-matrix elements distribution and the presentation of this by a ladder of fixed "resonances," is used for calculation of the self-shielding factors of 232Th. The results are given in comparison with those of the code NJOY and experimental data.JRC.D.5-Neutron physic

    Evaluation of neutron induced reaction cross sections in the resolved and unresolved resonance region at EC – JRC – IRMM

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    Recent efforts made at the EC-JRC-IRMM to produce evaluated cross section data files for neutron induced reactions are described as well as the methodology applied in both the resolved and unresolved resonance. for the resolved resonance region the paper focuses on a recent evaluation of isotopes present in natural cadmium. For the unresolved resonance region results for gold are presented

    Determination of the 232Th(n,gamma) Cross Section from 4 to 140 keV at GELINA

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    The neutron capture cross section of thorium has been masured in the energy region between 4 and 140 keV at the GELINA time-of-flight facility of the Institute for Reference Materials and Measurements in Geel, Belgium. The gamma-rays from capture events were detected by two C6D6 liquid scintillators, placed 14.37 m from the neutron source. The shape of the neutron flux was measured with a 10B-loaded ionization chamber. To obtain a detection efficienct independent of the gamma cascade and proportional to the total excitation energy, the pulsheight weighting technique was applied. The data have been normalized to the well-isolated and almost saturated 232Th resonance at 23.5 eV. The systematic uncertainties related to the normalization and weighting function, using an internal saturated resonance, are +- 1.5%. An additional systematic uncertainty of 0.5% results from the self-shielding and multiple scattering corrections. Between 4 and 140 keV, our date are +- 9 and 6.5% higher than the data of Kabayashi et al. and Macklin et al. respectively, and in good agreement with the data of Poenitz and Smith. below 15 keV our data deviate by up to 30% from the data reported by Wisshiak et al. Our dat have been analyzed in terms of average level parameters. The resulting parameters are consistent with the resolved resonance parameters deduced from the transmission measurements of Olsen et al.JRC.D.5-Neutron physic

    Recent Developments in the CONRAD Code regarding Experimental Corrections

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    The CONRAD code is an object-oriented software tool developed at CEA Cadarache since 2005 to deal with problems arising during the evaluation process (data assimilation and analysis, physical modelling, propagation of uncertainties…). This paper will present recent developments concerning the experimental corrections, which are required when a neutron resonance shape analysis is performed. Several experimental aspects are detailed in this work: the possibility to use spectra in energy as well as in time

    Evaluation of the Covariance Matrix of Estimated Resonance Parameters

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    In the resonance region nuclear resonance parameters are mostly obtained by a least square adjustment of a model to experimental data. Derived parameters can be mutually correlated through the adjustment procedure as well as through common experimental or model uncertainties. In this contribution we investigate four different methods to propagate the additional covariance caused by experimental or model uncertainties into the evaluation of the covariance matrix of the estimated parameters: (1) including the additional covariance into the experimental covariance matrix based on calculated or theoretical estimates of the data; (2) including the uncertainty affected parameter in the adjustment procedure; (3) evaluation of the full covariance matrix by Monte Carlo sampling of the common parameter; and (4) retroactively including the additional covariance by using the marginalization procedure of Habert et al.In the resonance region nuclear resonance parameters are mostly obtained by a least square adjustment of a model to experimental data. Derived parameters can be mutually correlated through the adjustment procedure as well as through common experimental or model uncertainties. In this contribution we investigate four different methods to propagate the additional covariance caused by experimental or model uncertainties into the evaluation of the covariance matrix of the estimated parameters: (1) including the additional covariance into the experimental covariance matrix based on calculated or theoretical estimates of the data; (2) including the uncertainty affected parameter in the adjustment procedure; (3) evaluation of the full covariance matrix by Monte Carlo sampling of the common parameter; and (4) retroactively including the additional covariance by using the marginalization procedure of Habert et al. © 2014

    Evaluation of neutron induced reaction cross sections in the resolved and unresolved resonance region at EC \u2013 JRC \u2013 IRMM

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    Recent efforts made at the EC-JRC-IRMM to produce evaluated cross section data files for neutron induced reactions are described as well as the methodology applied in both the resolved and unresolved resonance. for the resolved resonance region the paper focuses on a recent evaluation of isotopes present in natural cadmium. For the unresolved resonance region results for gold are presented. \ua9 Owned by the authors, published by EDP Sciences, 2013
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