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Precise gamma‐ray thermal neutron capture cross sections have been measured at the Budapest Reactor for all elements with Z = 1–83,92 except for He and Pm. These measurements and additional data from the literature been compiled to generate the Evaluated Gamma‐ray Activation File (EGAF), which is disseminated by LBNL and the IAEA. These data are nearly complete for most isotopes with Z

Precise gamma-ray thermal neutron capture cross sections have been measured at the Budapest Reactor for all elements with Z=1-83,92 except for He and Pm. These measurements and additional data from the literature been compiled to generate the Evaluated Gamma-ray Activation File (EGAF), which is disseminated by LBNL and the IAEA. These data are nearly complete for most isotopes with Z

We have developed NADS (Nuclear and Atomic Data System), a web‐based graphical interface for viewing pointwise and grouped cross sections and distributions. Our implementation is a client / server model. The client is a Java applet that displays the graphical interface, which has interactive 2‐D, 3‐D, and 4‐D plots and tables. The server, which can serve and perform computations of the data, has been implemented in Python using the FUDGE package developed by Bret Beck at LLNL. Computational capabilities include algebraic manipulation of nuclear evaluated data in databases such as LLNL’s ENDL‐99, ENDF/B‐V, and ENDF/B‐VI, as well as user data. Processed data used in LLNL’s transport codes are accessible as well. NADS is available from http://nuclear.llnl.gov/.

The Evaluated Gamma‐ray Activation File (EGAF), a new database of prompt and delayed neutron‐capture γ‐ray cross sections, has been prepared as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project to develop a “Database of Prompt Gamma‐rays from Slow Neutron Capture for Elemental Analysis.” Recent elemental γ‐ray cross‐section measurements performed with the guided neutron beam at the Budapest Reactor have been combined with data from the literature to produce the EGAF database. EGAF contains thermal cross sections for ≈35,000 prompt and delayed γ rays from 262 isotopes. New precise total thermal radiative cross sections have been derived for many isotopes from the primary and secondary gamma‐ray cross sections and additional level scheme data. An IAEA TECDOC describing the EGAF evaluation and tabulating the most prominent γ rays will be published in 2004. The TECDOC will include a CD‐ROM containing the EGAF database in both ENSDF and tabular formats with an interactive viewer for searching and displaying the data. The Isotopes Project, Lawrence Berkeley National Laboratory, continues to maintain and update the EGAF file. These data are available on the Internet from both the IAEA and Isotopes Project websites.

The Livermore Computational Nuclear Physics group is charged with producing updated neutron incident cross‐section evaluations for all the actinides in the coming year, concentrating on neutron‐induced fission, neutron capture, and (n,2n) cross sections. We attack this daunting task either by adopting other recent evaluations or by performing our own. Owing to the large number of nuclei involved, we seek to automate this process as much as possible. For this purpose, we have developed a series of computer codes: x4i, an interface to the EXFOR database, fete, a code that translates ENDF/B formatted evaluations into a computationally convenient form, and da_fit, a fitting code that takes all relevant EXFOR data for a reaction or set of reactions and performs a generalized least‐squares fit to them, subject to various constraints and other prior information.The Livermore Computational Nuclear Physics group is charged with producing updated neutron incident cross‐section evaluations for all the actinides in the coming year, concentrating on neutron‐induced fission, neutron capture, and (n,2n) cross sections. We attack this daunting task either by adopting other recent evaluations or by performing our own. Owing to the large number of nuclei involved, we seek to automate this process as much as possible. For this purpose, we have developed a series of computer codes: x4i, an interface to the EXFOR database, fete, a code that translates ENDF/B formatted evaluations into a computationally convenient form, and da_fit, a fitting code that takes all relevant EXFOR data for a reaction or set of reactions and performs a generalized least‐squares fit to them, subject to various constraints and other prior information.

The quasicontinuous decay spectrum of superdeformed excitations in 195Pb has been extracted. The slow increase of intensity as Eγ decreases is consistent with a level density of normal deformed excitations at ∼ 11ℏ with no gap parameter.

Prompt γ rays from the neutron-induced fission of 235U have been studied using the GEANIE spectrometer situated at the LANSCE/WNR “white” neutron facility. Gamma-ray production cross sections for 29 ground-state-band transitions in 18 even-even fission fragments were obtained as a function of incident neutron energy, using the time-of-flight technique. Independent yields were deduced from these cross sections and fitted with standard formulations of the fragment charge and mass distributions to study the transition from asymmetric to symmetric fission. The results are interpreted in the context of the disappearance of shell structure at high excitation energies.

High‐spin states in the neutron‐rich 106,108,110,111,112Rh isotopes have been investigated in the fission of the compound system formed in three heavy‐ion induced reactions. Four bands were assigned to 106,108,110,112Rh, respectively. Comparison with the lighter odd‐odd Rh isotopes supports the assignment of the bands to the πg9/2 ⊗ vh11/2 configuration. In 111Rh the level scheme consists of two rotational bands. In the ground‐state band the odd‐proton occupies the πg9/2 orbital.

GEANIE at LANSCE/WNR combines the precision energy resolution of germanium detectors with the advantages of a white source providing neutrons with energies 1 < E{sub n}(MeV) < 250 to address a variety of topics in nuclear physics. The authors present the analysis of two data sets, n+{sup 235}U and n+{sup 92}Mo, acquired at GEANIE during the 1998 beam cycle. These data showcase the breadth of subjects under study at this facility, including the spectroscopy of stable and near-stable nuclei, reaction dynamics, fission studies, and the relative population of isomer and ground states in neutron-induced reactions.

GEANIE is the first large-scale Ge detector array used in conjunction with a high-energy neutron spallation source. GEANIE consists of eleven Compton-suppressed planar detectors, nine suppressed and six unsuppressed co-axial detectors. Spallation neutrons are provided by the LANSCE/WNR facility, and reaction neutron energies are determined via time-of-flight. neutron flux is monitored in-beam with a fission chamber. GEANIE at LANSCE/WNR currently emphasizes the measurement of partial gamma-ray cross sections as a function of neutron energy. Absolute cross section measurements require a complete understanding of array performance. Important effects include intrinsic detector efficiency, beam and detector geometry corrections, target attenuation, and deadtime. Measurements and calculations of these effects will be presented for the specific cases of iron and actinide targets. The use of radioactive targets incurs a large deadtime penalty. In order to increase data throughput they are making plans to move to a triggerless data acquisition system. These modifications and other improvements to the electronics for better timing will be discussed.