New facility for neutron capture gamma-ray measurements at UMass Lowell Research Reactor*

Neutron capture reactions play a central role in nuclear science that transcends the boundaries between engineering (reactors, homeland security, nuclear non-proliferation, and oil-welling) and academic sciences (astrophysics and planetary science). For all these needs, reliable knowledge of absolute cross sections and discrete gamma-ray transition scheme is essential, but their reliability is often taken for granted. In a recent gap/discrepancy analysis using various nuclear data libraries, we identified data on many isotopes, particular those measured with a single gamma-ray detector during 70-80’s, in need of drastic revisions. New facility for measurements of capture gamma rays was designed and built at the University of Massachusetts Lowell’s 1 MW Research Reactor. The new measurements of neutron capture reactions are using the collimated thermal neutron beam at and the Mixed Array of Detectors (MAD), including high-resolution actively-suppressed high-purity germanium detectors. The measurements are carried out using modern high-density and high-speed digital data acquisition system that enables state-of-the-art coincidence spectroscopy of gamma-rays from excited compound nuclei after neutron capture. Comprehensive thermal cross sections and gamma-decay data will be created through the nuclear data evaluation process by partnership with a National Nuclear Data Center (NNDC) staff scientist at Brookhaven National Laboratory (BNL). In this talk we will present an overview of the current and future program at this facility,