Abstract and subjects
The long-lived rare earth isotopes Sm-151 (90 years, beta (max) = 76.3 keV) and Pm-147 (2.62 years, beta (max) = 224.6 keV) are low-yield fission products that generally require lengthy separation procedures to isolate and count by their beta emissions. We will describe novel liquid scintillation counting techniques using radioactive tracers to determine radiochemical yields from an environmental matrix. The recovery of Sm-151 is determined from the alpha decay (2.25 MeV) of Sm-147 in the natural Sm carrier and is in excellent agreement with the gravimetric recovery. The Pm-147 recovery is determined by the use of Pm-145 (17.7 years, EC) tracer, custom-produced at LANL using an isotopically enriched target of Sm-144. We have determined the Pm-145 recovery both from the 37.4 keV k(alpha 1) X-ray, and the electron-capture emissions by LSC. A comparison of these recovery methods is presented.