 |
Center for Nonlinear Studies |
The NIF laser is capable of producing a laboratory environment consisting of a hot plasma and a large neutron flux. These features make it uniquely suitable for carrying out experiments to investigate interactions between Plasma Physics and Nuclear Physics. A NIF Discovery Science experiment has recently been commissioned to measure the neutron capture cross section of Thulium 171 (Tm171), an isotope that plays an important role in the astrophysical s process, by imploding a capsule filled with deuterium and trace amounts of Tm171 using Polar Direct Drive. In the plasma environment of stars in which the s process occurs, significant populations of nuclear excited states can exist, with the neutron capture cross section varying for each state. Conventional laboratory experiments, e.g. using linear accelerators or spallation sources, can only measure cross sections of nuclei in the ground state. In contrast, NIF experiments can produce plasmas with ion temperatures of ~10 keV, which is sufficient to populate nuclear excited states of many nuclei, including Tm171, that participate in the s process. This talk will outline the challenges of making measurements of capture cross section, including those of excited state nuclei, on the NIF. These challenges include diagnosis of the plasma conditions, characterising the transport of dopants during the implosion, collecting and counting of neutron capture reaction products, and modeling of nuclear-plasma interaction processes and of nuclear reactions.
Host: William T. Taitano (T-5)