Many areas of applied nuclear science such as nuclear forensics,
stockpile stewardship, nuclear non-proliferation, and nuclear energy
require new or improved cross sections of neutron-induced reactions. The
state-of-the-art Detector for Advanced Neutron Capture Experiments
(DANCE) was designed and built to deliver high fidelity measurements of
neutron capture and neutron-induced fission cross sections on various
isotopes needed for these applications, using the neutron spallation
source at the Lujan Jr. Center, Los Alamos Neutron Scattering Center
(LANSCE). The DANCE array consists of 160 BaF2 gamma-ray detectors which
nearly covers the full 4pi solid angle. This enables DANCE to use total
gamma-ray calorimetry for the neutron capture, neutron-induced fission
and background characterization. A modern data acquisition is composed
of 324 channels of 500 MHz Acqiris digitizers and uses sophisticated on-
line and off-line data analyzers.
With DANCE, we have successfully measured neutron capture cross section
on 241Am over seven orders of magnitude of neutron energy, from thermal
to 320 keV. The methods for the absolute cross section determination
using the DANCE detectors array were developed to extract cross sections
and fit resonances below 20 eV using an R-matrix analysis. An accurate
modeling of the capture process coupled with a Geant4 software model of
the DANCE detector array was benchmarked against the experimental
results to an accuracy of a few percent. A variety of neutron capture
measurements for other actinide isotopes (233U to 243Am) and other
selected isotopes have also been undertaken and are currently being
analyzed using the methods developed for 241Am.
Techniques and results of measurements of neutron capture on fissioning
actinides at DANCE using a fission-tagging Parallel Plate Avalanche
Counter (PPAC) will also be presented. The first time observation of the
neutron capture on radioactive 242mAm in the resonance region was
performed.
Future projects will be briefly mentioned.
