7 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

    ENDF-6 compatible evaluation of neutron induced reaction cross sections for 106,108,110,111,112,113,114,116Cd

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    An ENDF-6 compatible evaluation for neutron induced reactions in the resonance region has been completed for 106,108,110,111,112,113,114,116Cd. 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-3.1.2 nuclear data library (or with the JEFF-Beta-CAD proposed evaluation in case of 113Cd). These files were produced for use in the JEFF32T2 library. For neutron induced reactions in the unresolved resonance region the JENDL-4.0 evaluation for 111Cd and 113Cd was adopted. 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 ACE files have been utilized to study the effect of the evaluated resonance parameters on results of integral experiments. 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

    Neutron-Induced Activation Cross Sections on Hafnium Isotopes from the Threshold to 20 Mev

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    Results of new cross section measurements are presented for the following neutron-induced reactions : 178Hf(n,alpha)175Yb, 180Hf(n,alpha)177Yb, 177Hf(n,p)177Lug, 178Hf(n,x)177Lug, 180Hf(n,p)180Lu, 180Hf(n,n'gamma)180Hfm, 174Hf(n,2n)173Hf, 176Hf(n,2n)175Hf, and 177Hf(n,3n)175Hf obtained with activation technique. The irradiations were carried out at the 7-MV Van de Graaff accelerator at IRMM, Geel. Quasi monoenergetic neutrons with energies between 14.8 and 20.5 MeV were produced via the 3H(d,n)4He reaction at Ed = 1, 1.4, 2, 3, and 4 MeV. The 3H(p,n)3He reaction was employed for the production of neutrons in the 2-3 MeV energy range. Both natural and enriched samples were used to facilitate correction for interference between reactions leading to the same product. The radioactivity of the samples was determined by standard gamma-ray spectrometry using HPGe detector. The current measurements are compared with the data from other authors and Evaluated Nuclear Data Files. Cross sections for three of the studied reactions are reported for the first time.JRC.DG.D.5-Nuclear physic

    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.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

    Determination of resonance parameters and their covariances from neutron induced reaction cross section data

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    Cross section data in the resolved and unresolved resonance region are represented by nuclear reaction formalisms using parameters which are determined by fitting them to experimental data. Therefore, the quality of evaluated cross sections in the resonance region strongly depends on the experimental data used in the adjustment process and an assessment of the experimental covariance data is of primary importance in determining the accuracy of evaluated cross section data. In this contribution, uncertainty components of experimental observables resulting from total and reaction cross section experiments are quantified by identifying the metrological parameters involved in the measurement, data reduction and analysis process. In addition, different methods that can be applied to propagate the covariance of the experimental observables (i.e. transmission and reaction yields) to the covariance of the resonance parameters are discussed and compared. The methods being discussed are: conventional uncertainty propagation, Monte Carlo sampling and marginalization. It is demonstrated that the final covariance matrix of the resonance parameters not only strongly depends on the type of experimental observables used in the adjustment process, the experimental conditions and the characteristics of the resonance structure, but also on the method that is used to propagate the covariances. Finally, a special data reduction concept and format is presented, which offers the possibility to store the full covariance information of experimental data in the EXFOR library and provides the required information to perform a full covariance evaluation.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard
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