(216a) Isotope Production at Brookhaven National Laboratory

The Brookhaven Linac Isotope Producer (BLIP) was the world's first facility to seriously exploit the isotope production capabilities of a high energy proton accelerator. The use of higher energy particles allows the use of relatively thick targets, where the large number of target nuclei can compensate for the generally smaller reaction cross sections compared to low energy nuclear reactions. The BLIP, built in 1972, utilizes the excess beam capacity of the 200 MeV proton Linac that injects into larger synchrotrons at BNL. A 30m long transport line delivers the protons to a shielded target area for radioisotope production. The maximum time averaged beam current is 105microampere and the proton energy can be varied incrementally from 118 to 200 MeV. The target assembly consists of an array of disk shaped target disks with the beam energy degrading as it penetrates from front to back. Since significant heat is deposited by the protons (up to 21 kW), all targets must be water cooled. After irradiations ranging from minutes to months, dependent on isotope half life and production needs, the targets are transferred to shielded hot cells. The irradiation creates many radioisotopes so that the product of interest must be chemically separated from coproduced impurities as well as the bulk target material. Standard techniques of analytic separation chemistry are used, such as anion and cation chromatography, solvent extraction, distillation, electrolysis, and precipitation. These processing techniques must then be adapted to the unique requirements of radiochemistry ? remote handling due to the hazards of radiation exposure and contamination , rapid separation times in order to minimize decay losses, and the separation of essentially massless (called carrier-free) amounts of product from bulk target. These techniques and some of the diagnostic or therapeutic medical applications of the radioisotopes prepared here (eg. Sr-82, Ge-68, Sn-117m etc) will be reviewed.