Pavlovsky, I. | Search NASA

DOE OSTI2019

Isotopic carbon targets

Neutron-rich isotopic 14 C targets are of interest to the nuclear physics community and would be in high demand at any thickness. Applied Nanotech, Inc. (ANI) has developed freestanding nat C and 13 C carbon foils fabricated using a drawdown printing technique. Isotopic enriched 13 C targets are produced at ANI, with the 14 C targets to be fabricated at Argonne National Laboratory (ANL) using stock material available at Argonne. The 14 C target material is nominally enriched to ~73% 14 C and will contain 2.2% organic binder. The fabrication process is highly material-efficient and can be used to produce targets that are difficult to fabricate by other methods. Finally, to be developed, 12 C ( 13 C-depleted natural carbon) which could also be used in accelerators for target applications.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2019

Isotopic targets with graphene backing

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 (3550ºC 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 11 B target with a 0.5 mg/cm 2 on graphene film. The 11 B isotope is of interest due to aneutronic proton–boron fusion reaction 1 p + 11 B → 3 4 He + 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 52 Cr (p,n) 52 Mn. 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. Finally, we fabricated nat Ir, nat Re, nat WO3, and nat HfO 2 nanoparticle-loaded graphene targets that can be used in nuclear physics research.

36 MATERIALS SCIENCE↗