The Production of Spallation Radionuclides for Medical Applications at BLIP

The Brookhaven LINAC Isotope Producer (BLIP) is the first facility to demonstrate the capability of a large linear accelerator for efficient and economical production of difficult-to-make, medically useful radionuclides. It utilizes the excess beam capacity of a LINAC that injects 200 MeV protons into the 33 GeV Alternating Gradient Synchrotron. The LINAC provides an integrated beam current of 60 μA for radionuclide production, operating 24 hours per day, 7 days per week. The 200 MeV proton energy is very suitable for isotope production since the spallation process provides a route to copious quantities of radionuclides unavailable at lower energy accelerators, or reactors. Further, the energy is high enough to allow simultaneous irradiation of multiple targets leading to reduced cost per nuclide. Careful choice of target position in the array makes it possible to select the proper proton energy range to maximize the yield of a particular nuclide from a given target and minimize the amounts of undesirable by-products. The proton beam enters the BLIP irradiation chamber under 32 feet of water which serves as a transparent shield for gamma rays and the high energy neutrons produced by spallation interactions. Guide tubes are used for introducing independent target assemblies into the proton beam, enabling both very short irradiations and very long ones. The targets are individually water cooled by means of a flexible stainless steel water hose that travels with the assembly. The basic target types are encapsulated salt pellets, gases, and metallic foils.