Isotopic targets with graphene backing

Abstract

Many of the isotopes cannot be made as free-standing targets and require thin film backing. Low-Z backing materials, such as amorphous carbon and thin polymer films are materials of choice for some experiments. However, the limitations of these backing materials are poor thermal and mechanical stability. All-carbon graphene films would be an excellent choice as a backing material due to their high thermal conductivity, high temperature tolerance (3550°C melting point), low outgassing, mechanical integrity, and ease of handling. We fabricated a variety of targets using graphene material as a backing or a host matrix. Using PVD sputtering deposition of boron-11 carbide, we fabricated 11B target with a 0.5 mg/cm2 on graphene film. The 11B isotope is of interest due to aneutronic proton-boron fusion reaction 1p+11B → 3 4He+8.7 MeV suitable for clean energy production1. We also prepared a neutron rich natCr target on graphene backing by electroplating Cr in an aqueous chromium (III) oxide bath. The chromium target can be used for production of positron emitting Mn radioisotope2 in the reaction 52Cr (p,n) 52Mn. One of the unique advantages of the graphene film fabrication process is the capability to embed target materials, including refractory metals, in the nanoparticle form into a host graphene matrix during target preparation. We fabricated natIr, natRe, natWO3, and natHfO2 nanoparticle-loaded graphene targets that can be used in nuclear physics research.