Isomer population control via direct irradiation of solid-density targets using a laser-plasma accelerator*

A small component of spent nuclear fuel is both highly radioactive and long-enough lived to require costly long-term storage. Efforts to reduce these lifetimes through excitation into the quasicontinuum via nuclear-plasma interactions are underway. We present our results on using a hundred terawatt laser-plasma accelerator to excite Bromine nuclei through pulsed ultra-fast (<100 fs) direct irradiation of solid-density active targets. These targets are excited through the absorption of real and virtual <35 MeV photons. The resulting population of excited states indicates contributions from mechanisms other than photoabsorption, such as inelastic electron scattering, while providing a sensitive probe of gamma strength and level densities in the nuclear quasicontinuum. Further probing of these electron-nuclear interactions could have far-reaching impact, such as assisting in the development of clean energy sources and developing our understanding of heavy element formation in stellar interiors.