Fast Heavy Ion Beams in an Aqueous Target

Emily Abel, Michigan State University

Photo of Emily Abel

Nuclear medicine can be used for both imaging and therapy of many diseases, especially forms of metastatic cancer. Some promising radionuclides such as bromine-76, which can be used for imaging, and scandium-47 and astatine-211, which can be used for therapy, are difficult to produce. However, at the National Superconducting Cyclotron Laboratory (NSCL) and in the future at the Facility for Rare Isotopes Beams (FRIB), we have the opportunity to harvest these radionuclides when the calcium-48, krypton-78 and uranium-238 primary beams are run to produce a user-specified secondary radioactive beam. Much of the primary beam goes unreacted and is collected in beam stops. By stopping the unused primary beam in an aqueous target, additional nuclear reactions are induced, producing radionuclides such as those that are interesting for nuclear medicine applications. Current radiochemistry efforts at the NSCL involve making a beam blocker system that can handle the harsh chemical conditions created when a fast heavy ion beam enters water. These conditions are produced by radiolysis, or the breakup of molecules when a beam of ionizing radiation enters a material. A recent preliminary experiment was run at the NSCL using a 40Ca20+ primary beam and the most recent design of the beam blocker system. In this experiment, the condition of the water was monitored using sensors such as a pH probe, a conductivity probe, a dissolved O2 sensor and a H2 sensor. Additionally, the titanium alloy that served as the window through which the beam entered the aqueous target was analyzed for degradation. The radionuclides that were produced in the system through nuclear reactions were also identified and quantified using gamma spectroscopy. The results of this experiment will be presented and discussed.

Abstract Author(s): E.P. Abel, H. Clause, G. Severin