Neutron capture reactions for nuclear astrophysics and national security applications
High-accuracy neutron capture cross sections are required not only for nuclear astrophysics modeling, but also for a variety of applications ranging from nuclear energy, stockpile stewardship to national security. Frequently, those reactions pose a challenge for direct measurements, thus indirect techniques are employed to extract the cross sections.
One of the methods, the Oslo methods, allows for extracting the nuclear statistical properties from the experimental data. Those are then used to calculate the capture cross sections through the Hauser-Feshbach statistical approach. This talk will focus on the measurements performed at Texas A&M using the Hyperion array to employ the Oslo technique. Here, the Oslo method was for the first time employed to investigate rare-earth nuclei and unraveled a new feature, the low-energy upbend, in the gamma-ray strength function for these nuclei. Systematic measurements show that this feature is present in all nuclei, regardless of their shape and has a significant impact on the cross section. Cross sections obtained from the measured statistical properties will be presented, with experimental uncertainties propagated using Monte Carlo approach.
When direct measurements are possible, e.g. for stable targets, the key limiting factor to the precision of the measurement is the resolution of the neutron beam energy. The second part of this talk will focus on the Neutron Irradiation Station at the Nuclear Science Lab at the University of Notre Dame. The project funded by the DOE-NE is going to deliver high resolution flux of neutrons to ensure high-precision measurements of cross sections for neutron-induced reactions.
Bio: Anna Simon is an associated professor in the Department of Physics at the University of Notre Dame. She received her Ph.D. from Jagiellonian University in Krakow, Poland, where she worked in experimental atomic physics. In 2010, she joined the National Superconducting Cyclotron Laboratory at Michigan State University as a postdoc where she measured capture reactions relevant for the astrophysical p-process. Her second postdoc position at University of Richmond involved nuclear reactions studies with the focus on indirect measurements of neutron capture cross sections.
Her current research interest combine nuclear astrophysics and nuclear reactions. She utilized various experimental techniques to constrain cross section data crucial for the nucleosynthesis models for production of heavy nuclei. Additionally, she is interested in applications of her work to national security and stockpile stewardship, where cross sections for neutron-induced reactions play critical role.