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We describe the next generation general purpose Evaluated Nuclear Data File, ENDF/B-VII.0, of recommended nuclear data for advanced nuclear science and technology applications. The library, released by the U.S. Cross Section Evaluation Working Group (CSEWG) in December 2006, contains data primarily for reactions with incident neutrons, protons, and photons on almost 400 isotopes. The new evaluations are based on both experimental data and nuclear reaction theory predictions.The principal advances over the previous ENDF/B-VI library are the following: (1) New cross sections for U, Pu, Th, Np and Am actinide isotopes, with improved performance in integral validation criticality and neutron transmission benchmark tests; (2) More precise standard cross sections for neutron reactions on H, 6 Li, 10 B, Au and for 235,238 U fission, developed by a collaboration with the IAEA and the OECD/NEA Working Party on Evaluation Cooperation (WPEC); (3) Improved thermal neutron scattering; (4) An extensive set of neutron cross sections on fission products developed through a WPEC collaboration; (5) A large suite of photonuclear reactions; (6) Extension of many neutron-and proton-induced reactions up to an energy of 150 MeV; (7) Many new light nucleus neutron and proton reactions; (8) Post-fission beta-delayed photon decay spectra; (9) New radioactive decay data; and (10) New methods developed to provide uncertainties and covariances, together with covariance evaluations for some sample cases.The paper provides an overview of this library, consisting of 14 sublibraries in the same, ENDF-6 format, as the earlier ENDF/B-VI library. We describe each of the 14 sublibraries, focusing on neutron reactions. Extensive validation, using radiation transport codes to simulate measured critical assemblies, show major improvements: (a) The long-standing underprediction of low enriched U thermal assemblies is removed; (b) The 238 U, 208 Pb, and 9 Be reflector biases in fast systems are largely removed; (c) ENDF/B-VI.8 good agreement for simulations of highly enriched uranium assemblies is preserved; (d) The underprediction of fast criticality of 233,235 U and 239 Pu assemblies is removed; and (e) The intermediate spectrum critical assemblies are predicted more accurately.We anticipate that the new library will play an important role in nuclear technology applications, including transport simulations supporting national security, nonproliferation, advanced reactor and fuel cycle concepts, criticality safety, medicine, space applications, nuclear astrophysics, and nuclear physics facility design. The ENDF/B-VII.0 library is archived at the National Nuclear Data Center,

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The joint evaluated fission and fusion nuclear data library 3.3 is described. New evaluations for neutroninduced interactions with the major actinides 235 U, 238 U and 239 Pu, on 241 Am and 23 Na, 59 Ni, Cr, Cu, Zr, Cd, Hf, W, Au, Pb and Bi are presented. It includes new fission yields, prompt fission neutron spectra and average number of neutrons per fission. In addition, new data for radioactive decay, thermal neutron scattering, gamma-ray emission, neutron activation, delayed neutrons and displacement damage are presented. JEFF-3.3 was complemented by files from the TENDL project. The libraries for photon, proton, deuteron, triton, helion and alpha-particle induced reactions are from TENDL-2017. The demands for uncertainty quantification in modeling led to many new covariance data for the evaluations. A comparison between results from model calculations using the JEFF-3.3 library and those from benchmark experiments for criticality, delayed neutron yields, shielding and decay heat, reveals that JEFF-3.3 performes very well for a wide range of nuclear technology applications, in particular nuclear energy.

We have made new, improved measurements of the Si28-30 (n, gamma) cross sections and have done a resonance analysis of these data including previous total cross sections. Together with the calculated contributions due to direct capture, we calculated the astrophysical (n, gamma) reaction rates and investigated the s-process abundances of the Si isotopes. Measured isotopic anomalies of intermediate and heavy elements in SiC grains from meteorites appear to be attributable to the s-process in asymptotic giant branch (AGB) stars. But the Si isotopic ratios in these grains are substantially different than s-process models predict. Therefore, recent papers have invoked galactic chemical evolution or other effects to explain the Si isotope ratios in these grains. Our new reaction rates are significantly different than previous rates, and s-process calculations using these rates lead to much larger isotopic shifts in Si-30. However, these exploratory calculations demonstrate that even with these substantially different rates the large observed variation in SiC grain from AGB stars cannot be explained by standard s-process models

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The Oak Ridge Electron Linear Accelerator ͑ORELA͒ was used to measure neutron total and capture cross sections of natural chlorine in the energy range from 100 eV to 600 keV. We performed an R-matrix analysis of our new capture and transmission data up to 500 keV. From these resonance parameters new (n,␥) astrophysical reaction rates were determined over the entire energy range needed by the latest stellar models of the s process.In data libraries such as ENDF/B-VI ͓1͔ or JENDL-3.2 ͓2͔ most of the older neutron induced cross section data show deficiencies or do not cover the neutron energy range which is currently important for a wide variety of applications. Many of the older measurements suffered from poor time-offlight ͑TOF͒ resolution, and because of computer storage limitations the description of some data in the neutron energy range above several tens of keV is crude. Consequently, the number of data points may not describe the resonances accurately enough in order to apply certain corrections, such as self-shielding, multiple scattering, or Doppler broadening of individual resonances. This impacts not only the resolved cross section region but also the unresolved region, and could lead to problems in the correct processing of data from data libraries and eventually to erroneous Maxwellian averaged cross sections ͑MACS͒. These cross sections are input parameters for asymptotic giant branch stellar models which describe the synthesis of the elements via a chain of neutron capture reactions and ␤ decays called the s process.In the case of chlorine, the total cross section data below 200 keV used in the evaluated nuclear data files rely only on low resolution transmission measurements ͓3,4͔. Even though there exist high-resolution transmission measurements ͓5͔ for chlorine, they do not cover the neutron energy range below 500 keV, which is important for the calculation of the MACS needed by the stellar models. There exists only one high-resolution neutron capture measurement for Cl ͓6͔ performed at ORELA, using a natural chlorine and an enriched sample for 37 Cl. But this experiment had a low energy cutoff at 4 keV, and the analyzed resonance region up to 220 keV was covered only for 35 Cl. In the case of 37 Cl the analysis stopped at 150 keV. An important drawback of this capture experiment was the lack of high precision total cross section measurements. Since the (n,␥) measurements are usually performed with rather thick samples, as was the case in Ref. ͓6͔, corrections in the resonance analysis have to be applied for self-shielding and multiple scattering. This requires highresolution transmission data and accurate neutron widths, and the analysis performed by Ref. ͓6͔ used the ⌫ n from the low resolution transmission experiment of Ref. ͓4͔. Therefore we made new transmission and neutron capture measurements for chlorine.The experiments were performed using ORELA ͓7͔, which is a high intensity white neutron source with excellent timing resolution in the keV neutron energy range. Over the past 30 years ORELA...

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