Carbon Stripper Foil for the Next Generation Rare Isotope Beam Facility

The Facility for Rare Isotope Beams (FRIB) will be a key tool for nuclear science that promises to change the way we view and describe the nucleus. A charge stripper foil is an essential device in a heavy-ion accelerator; they increase the variety of acceleration schemes and decrease the accelerator construction cost. The FRIB facility will require a stripper foil that can sustain a beam power loss of 1 kW. To handle such a high power load over a small beam size (about 1 mm diameter), the design of the stripper foil includes a need for large area, robust carbon foils. These foils are typically expensive to make, are fragile and are difficult to make over large area (eventually we may need to scale to 30 cm diameter). There is a need for a stripper foil in the range of 0.5 mg/cm2 that is low-Z, thermally conductive, mechanically robust, has high uniformity and can be fabricated over large areas at low cost. In addition, researchers at the ATLAS accelerator at Argonne National Laboratory have a need to replace metal foils as windows for gas targets such as are currently used for in-beam reactions to generate secondary radioactive beams. The overall goal of this two phase program is to develop robust carbon foils that can be made over large areas at low cost for stripper foil and windows for gas targets. We will address this problem by using vacuum filtration methods to make carbon foils from graphene and carbon nanotubes. The Phase I effort demonstrated that graphene foils are feasible materials for ion stripper foil applications. The methods used can be scaled to large area and they show superior uniformity. We also demonstrated feasibility to use this foils for gas target window application. The overall technical objective of this Phase II program will be to increase the foil diameter to > 15 cm, demonstrate uniformity over this area and demonstrate mechanical robustness of the foils, even when taken to high temperature. FRIB will produce key new rare isotopes of atomic nuclei that are essential for our understanding of the universe. It is the overall consensus of the international nuclear structure and nuclear astrophysics communities that the future of the study of atomic nuclei centers on and requires advanced facilities for access to exotic nuclei. Commercial Applications and Other Benefits: FRIB will have profound benefits to society; it will play an important role in the 21st Century