Isotope Harvesting Potential at the Facility for Rare Isotope Beams
Background and Motivation
The Facility for Rare Isotope Beams (FRIB) will be a new national user facility for nuclear science, funded by the Department of Energy Office of Science (DOE-SC) Office of Nuclear Physics and operated by Michigan State University (MSU). The wide variety of isotopes produced by the new FRIB will allow for new opportunities in the field of isotopes for many applications. Secondary beam intensities on the order of 1010 particles per second (and in some cases greater amounts) will make it possible for large quantities of many isotopes to be harvested. These isotopes would most likely be collected in a parasitic fashion from various collection points while FRIB is producing other isotopes for experiments in nuclear physics. The potential applications of these harvested isotopes range from the determination of neutron cross sections for homeland security to kinetic studies of radionuclide uptake in biological processes.
The new Facility for Rare Isotope Beams will generate a number of isotopes not currently available. Harvesting of radioactive species from FRIB will benefit many programs including basic physics, medicine, environmental science, and stockpile stewardship. Both dedicated and parasitic collection can provide isotopes for which there is currently no comparable source. There are compelling scientific opportunities resulting from collection of isotopes from various sites within the production target facility at FRIB.
The standard mode of operation at FRIB will be to produce a rare isotope beam for a primary user, for example 60Ca from a 82Se beam. At the same time, the fragmentation or fission of the production beam will produce up to 1000 other isotopes that could be collected (harvested) and used for other experiments or applications.
A high-level overview of possible applications for isotopes produced at FRIB is given in the report Scientific Opportunities with a Rare-Isotope Facility in the United States written by the Rare Isotope Science Assessment Committee, National Research Council (National Academies Press, 2007) and in the RIA (now FRIB) Applications Workshop.
• Nuclear power (nuclear data is needed to optimize reactor design, safeguards applications, and for studies related to reprocessing or disposal of nuclear waste)
• Homeland security (nuclear data is needed for modeling of nuclear reactions, detection of nuclear material and other threats, and development and calibration of threat detection technologies)
• Stockpile stewardship (nuclear data is needed for modeling of nuclear reaction networks, similar to astrophysics studies, such as (n,2n), (n,γ), (n,p), and (n,f))
• Medical diagnostics and therapy (development of new imaging and treatment technologies, kinetic studies of material uptake in the body, and the possible production of biomedical radioisotopes for diagnostics and therapy)
• Nanoprobes for materials science using radioisotopes (for example the use of polarized 8Li)
• Industrial and environmental tracers (for example 7Be, 210Pb, 137Cs, etc.)
A working group on Isotope Harvesting has been established to investigate the feasibility of isotope harvesting at FRIB. The Isotope Harvesting group convened September 29 – October 1, 2010 in Santa Fe, NM. Following an overview of FRIB operations and design, reviews regarding isotope needs for astrophysics, stewardship science, medical, and other industries were presented. Smaller working groups were formed to identify and rank isotope needs for particular applications. Priority isotopes were identified and are shown in Table 1.
Table 1. Priority isotopes for harvesting at FRIB. These isotopes were identified at the Working Group meeting in Santa Fe, NM September 30 – October 1, 2010.
Outline of Work Plan and Strategy
Although FRIB is scheduled to be commissioned in ~2020, there is significant work to be conducted now in order to assess the feasibility of isotope harvesting at FRIB. This work falls into 3 task:
1. Conduct offline experiments to develop radiochemistry techniques pertaining to isotope harvesting including modeling of heavy ion beam interactions with water and other potential implantation materials.
2. Conduct online experiments at with the existing ion beam facilities at the NSCL in order to make estimates of yields available post-separation.
3. Design potential isotope harvesting stations that are synergistic with the existing production target facilities to be constructed at FRIB. Account for the need to scale-up radiochemical procedures.