M. Herman

Towards a More Complete and Accurate Experimental Nuclear Reaction Data Library (EXFOR). International Collaboration Between Nuclear Reaction Data Centres (NRDC)

The International Network of Nuclear Reaction Data Centres (NRDC) coordinated by the IAEA Nuclear Data Section (NDS) successfully collaborates in the maintenance and development of the EXFOR library. As the scope of published data expands (e.g. to higher energy, to heavier projectile) to meet the needs of research and applications, it has become a challenging task to maintain both the completeness and accuracy of the EXFOR library. Evolution of the library highlighting recent developments is described.

Recent Developments of the Nuclear Reaction Model Code EMPIRE

Recent extensions and improvements of the EMPIRE code system are outlined. They add to the code new capabilities such as fission of actinides, preequilibrium emission of clusters, photo‐nuclear reactions, and reactions on excited targets. These features, along with improved ENDF formatting, exclusive spectra, and recoils make the forthcoming 2.19 release a complete tool for evaluation of nuclear data at incident energies above the resonance region.

EXFOR‐CINDA‐ENDF: Migration of Databases to Give Higher‐Quality Nuclear Data Services

Extensive work began in 1999 to migrate the EXFOR, CINDA, and ENDF nuclear reaction databases, and convert the available nuclear data services from VMS to a modern computing environment. This work has been performed through co‐operative efforts between the IAEA Nuclear Data Section (IAEA‐NDS) and the National Nuclear Data Center (NNDC), Brookhaven National Laboratory. The project also afforded the opportunity to make general revisions and improvements to the nuclear reaction data services by taking account of past experience with the old system and users’ feedback. A main goal of the project was to implement databases in a relational form that provides full functionality for maintenance by data centre staff and improved retrieval capability for external users. As a result, the quality of our nuclear service has significantly improved, with better functionality of the system, accessibility of data, and improved data retrieval functions for users involved in a wide range of applications.

Nuclear Data Resources for Capture γ‐Ray Spectroscopy and Related Topics

We discuss nuclear data resources of the National Nuclear Data Center (NNDC) of relevance to nuclear structure, reactions, astrophysics as well as applied technology applications. These resources include databases, tools, publications and powerful Web service at http://www.nndc.bnl.gov.

Nuclear Reaction and Structure Databases of the National Nuclear Data Center

The National Nuclear Data Center (NNDC) collects, evaluates, and disseminates nuclear physics data for basic research and applied nuclear technologies. In 2004, the NNDC migrated all databases into modern relational database software, installed new generation of Linux servers and developed new Java‐based Web service. This nuclear database development means much faster, more flexible and more convenient service to all users in the United States. These nuclear reaction and structure database developments as well as related Web services are briefly described.

Derivation of an optical potential for statically deformed rare-earth nuclei from a global spherical potential

The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations characterized by nuclear deformations. A proper treatment of such excitations is often essential to the accurate description of experimental nuclear-reaction data and to the prediction of a wide variety of scattering observables. Stimulated by recent work substantiating the near validity of the adiabatic approximation in coupled-channel calculations for scattering on statically deformed nuclei, we explore the possibility of generalizing a global spherical optical model potential (OMP) to make it usable in coupled-channel calculations on this class of nuclei. To do this, we have deformed the Koning-Delaroche global spherical potential for neutrons, coupling a sufficient number of states of the ground state band to ensure convergence. We present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions for neutron-induced reactions on statically deformed nuclei in the rare-earth region. We choose isotopes of three rare-earth elements (Gd, Ho, W), which are known to be nearly perfect rotors, to exemplify the results of the proposed method. Predictions from our model for total, elastic and inelastic cross sections, as well as for elasticmorexa0» and inelastic angular distributions, are in reasonable agreement with measured experimental data. In conclusion, these results suggest that the deformed Koning-Delaroche potential provides a useful regional neutron optical potential for the statically deformed rare earth nuclei.«xa0less

Coupled channels optical model potential for rare earth nuclei

The global spherical optical model by Koning and Delaroche is generalized to enable its use in coupled-channel calculations on well deformed nuclei in the rare-earth region. The generalization consists in adding the coupling of the ground state rotational band, deforming the potential by introducing appropriate quadrupole and hexadecupole deformations and correcting the optical model potential radius to preserve the volume integral of the spherical optical potential. We choose isotopes of three rare-earth elements (W, Ho, Gd), which are known to be nearly perfect rotors, to perform a consistency test of our conjecture on integrated cross sections as well as on angular distributions for elastic and inelastic neutron scattering. The only additional input are experimentally determined deformations, which we employ without any adjustments. The results are clearly superior compared to the spherical optical model calculations with dramatic improvement at low incident energies.

Validation of Monte Carlo Pre-Equilibrium Model (HMS)

The Hybrid Monte Carlo Simulation (HMS) model of preequilibrium emission has been validated against 150 neutron‐ (partially proton‐) induced reactions on 35 target nuclei by comparing calculated nucleon emission spectra with angle‐integrated experimental data. Free‐scattering damping width was assessed to represent good approximation to the magnitude of the pre‐equilibrium processes, and found suitable for theoretical predictions and evaluations of nuclear reaction data.

NNDC Stand: Activities and Services of the National Nuclear Data Center

The National Nuclear Data Center (NNDC) collects, evaluates, and disseminates nuclear physics data for basic nuclear research, applied nuclear technologies including energy, shielding, medical and homeland security. In 2004, to answer the needs of nuclear data users community, NNDC completed a project to modernize data storage and management of its databases and began offering new nuclear data Web services. The principles of database and Web application development as well as related nuclear reaction and structure database services are briefly described.

Neutron Cross‐Section Evaluations for 70,72,73,74,76Ge

Entirely new evaluations have been performed for neutrons on all isotopes of Ge, from a thermal energy up to 20 MeV, with a focus on photon production. The resonance parameters were considerably improved compared to earlier evaluations. The fast‐neutron region has been evaluated using the EMPIRE‐2.19 code. The results were validated against photon data on Fe and Nb. Isotopic evaluations for Ge were summed up and compared with available measurements on natural Ge. Various quantities related to photon production, showing strong dependence on neutron incident energy, are discussed.