Pavel Oblozinsky NSDD’07, St. Petersburg June 11-15, 2007 ENDF/B-VII.0 Library and Use of ENSDF Pavel Oblozinsky National Nuclear Data Center Brookhaven National Laboratory Brookhaven Science Associates

Pavel Oblozinsky NSDD’07, St. Petersburg June 11-15, Releases of ENDF/B library: Historical sequence 1968: ENDF/B-I 1970: ENDF/B-II 2 years 1972: ENDF/B-III 2 years 1974: ENDF/B-IV 2 years 1978: ENDF/B-V 4 years 1990: ENDF/B-VI12 years 2006: ENDF/B-VII16 years ENDF/B-VII library will be in use for many years, possibly decades! It will serve as the physics basis of many nuclear technologies, including nuclear power, national security, fusion, shielding, accelerator design, etc. Evaluated Nuclear Data File, ENDF/B Contains primarily cross sections for applied technology

Pavel Oblozinsky NSDD’07, St. Petersburg June 11-15, ENDF/B-VII.0 released in Dec 2006, the first major release since 1990 Special issue of Nuclear Data Sheets published in December 2006 Special issue of Nuclear Data Sheets “Big paper” on ENDF/B-VII.0 by Chadwick et al. (48 co-authors) Benchmarking ENDF/B-VII.0 by van der Marck, NRG Petten 700 copies purchased by BNL and LANL, more than 650 copies distributed ENDF/B-VII.0 Library Release December 2006

Pavel Oblozinsky NSDD’07, St. Petersburg June 11-15, New sublibraries: Neutron standards cross sections, photonuclear Large improvements: Neutron reaction sublibrary, charged particles, decay data, thermal neutron scattering sublibrary No changes: Fission yields, atomic data (taken over from ENDF/B-VI.8) ENDF/B-VII.0 Library Contents 14 sublibraries, many additions and improvements LANL, IAEA LANL, ORNL, BNL BNL LANL IAEA-NEA-NIST-LANL LANL

Pavel Oblozinsky NSDD’07, St. Petersburg June 11-15, ENDF/B-VII.0 decay data sublibrary: Almost entirely based on ENSDF Decay data sublibrary is primarily used in heat calculations (energy released in radioactive decay in nuclear power reactors). Previous version of the decay data sublibrary was produced in ~1988 using ENSDF 1985 data, mostly by T. England, LANL and Charlie Reich, Idaho, and contained 979 materials (isotopes). New version was produced by A. Sonzogni, NNDC, in It is based on the most recent version of ENSDF. It contains data for 3,838 materials (isotopes, including isomers). More details are given in talk by Alejandro.

Pavel Oblozinsky NSDD’07, St. Petersburg June 11-15, ENDF/B-VII.0 is nuclear reaction library: What is the role of ENSDF in cross section evaluations? Contrary to ENSDF, cross section evaluations are heavily based on nuclear model calculations for which discrete levels and decay schemes are the most important quantities. ENDF evaluator can take these data conveniently from the Reference Input Parameter Library (RIPL, segment Levels, maintained by IAEA) that is largely based on ENSDF. This has several practical advantages: ENSDF format is too cumbersome to be coupled to cross-section codes such as EMPIRE, TALYS or GNASH. Cross-section evaluator often needs data not uniquely identified in ENSDF. In RIPL these gaps are filled-in using statistical methods (missing spins, parities, etc). In other cases calculations were used (missing conversion coefficients). RIPL provides other derived information: Estimates of cut-off energies for completeness of level schemes. Temperatures deduced from cumulative plots for constant-temperature level densities.

Pavel Oblozinsky NSDD’07, St. Petersburg June 11-15, ENDF/B-VII.0 is nuclear reaction library: What is the role of ENSDF in cross section evaluations? Low-lying discrete levels (completeness is essential, but this is not always the case in ENSDF) are used to adjust nuclear level densities that are of crucial importance in Hauser- Feshbach statistical model cross section calculations.

Pavel Oblozinsky NSDD’07, St. Petersburg June 11-15, ENDF/B-VII.0 is nuclear reaction library What is the role of ENSDF in cross section evaluations? Realistic decay schemes (based on ENSDF) are used to calculate cross sections for population of low-lying levels. This is important for isomeric cross sections and also for gamma production cross sections. Other data of interest: atomic masses (Q-values), deformation parameters, collective levels, internal conversion coefficients. Light nuclei include a number of technologically important materials (H, He, Li, Be, B, C, N, O) where structure data are needed for cross section evaluations using R-matrix approach (code EDA by Los Alamos).

Pavel Oblozinsky NSDD’07, St. Petersburg June 11-15, ENDF/B-VII.0 is nuclear reaction library What is the role of ENSDF in cross section evaluations? Conclusion ENSDF plays important, in some sense even crucial, role in nuclear reaction evaluations.