Search

The gadolinium isotopes are interesting for reactor applications as well as for medicine and astrophysics. The gadolinium isotopes have some of the largest neutron capture cross sections. As a consequence they are used in the control rod in reactor fuel assembly. From the basic science point of view, there are seven stable isotopes of gadolinium with varying degrees of deformation. Therefore they provide a good testing ground for the study of deformation dependent structure such as the scissors mode. Decay gamma rays following neutron capture on Gd isotopes are detected by the DANCE array, which is located at flight path 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation and close packing of the detector array enable gamma-ray multiplicity measurements. The calorimetric properties of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a specific isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles gamma-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. Various photon strength function models are used for comparison with experimentally measured DANCE data and provide insight for understanding the statistical decay properties of deformed nuclei. [ABSTRACT FROM AUTHOR]

GEANIE is an array of 26 HpGe detectors used to study nuclear reaction dynamics and structure following reactions with high-energy (1 < E[sub n] < 200 MeV) neutrons, for both basic and applied research projects. Studies have included the measurement of (n,xn) partial cross sections as a function of E[sub n] for a variety of nuclei, particularly actinides. More recently, studies of n-induced fission-fragment distributions and nuclear structure in the actinide region have been started. A second beam line and experimental station (FIGARO) have been set up to complement and extend this program. Research conducted on this second beam line includes the use of conversion electron spectroscopy to explore nuclear structure, using the University of Pittsburgh ICEBall II array. [ABSTRACT FROM AUTHOR]

We present the new FIGARO facility under construction at the Weapons Neutron Research facility at LANSCE, for the measurement of γ rays and neutrons from interactions of fast neutrons with nuclei. A first measurement was performed in 1999 with [sup 59]Co, using a single germanium detector. Prompt γ rays from reactions with neutrons in the energy range from 1 to 200 MeV have been measured. Preliminary cross sections for γ transitions from (n, n'), (n, 2n), (n, 3n), (n, p), (n, np), (n, 2np) and (n, α) reactions have been obtained. The results have been compared with existing data, and with calculations using the code GNASH. They indicate that with FIGARO high quality data can be obtained in the considered energy range. [ABSTRACT FROM AUTHOR]