Pushing toward better nuclear data
Researchers probe many important nuclear reactions using collisions produced with accelerators. Gleaning good data on some fundamental reactions can be problematic, however. For example, low-energy cross sections often need to be extrapolated from high-energy measurements. In those and other cases, nuclear physics research benefits from an enlarged toolkit for measurement of basic cross-section data.
Writing in Physical Review Letters, Johan Frenje at the Massachusetts Institute of Technology, Cambridge, and colleagues report their use of data obtained in laser-driven inertial confinement fusion experiments to extract precise cross sections for important light-ion interactions in which neutrons scatter off deuterons ( H) and tritons ( H).
The research team created high-density plasmas by using the OMEGA laser system to implode glass capsules filled with deuterium and tritium. Sixty powerful laser beams strike the outer surface of the capsule, generating a plasma that then pushes it inward to compress the gas. As the gas reaches thermonuclear conditions, reactions create neutrons that collide with the hydrogen isotopes, and scattering cross sections are extracted from the energy spectra of these species. The results match ab initio calculations well, providing not only a boost to theory but also data on reactions of crucial importance to nuclear astrophysics and fusion energy research. – David Voss