Nuclear decay studies of fission-product nuclides using an on-line mass separation technique

An isotope-separator-on-line (ISOL) system has been developed at the Idaho National Engineering Laboratory to enable a wide variety of nuclear decay studies to be made for fission-product radionuclides. The system is unique in that it utilizes the spontaneous fission source,²⁵²Cf, as the source of fission-product radioactivity. Fission products are transported to the ion source of the mass separator by the helium gas-jet technique. Mass-separated beams of previously unattainable rare-earth nuclides are produced with this system because of the higher yield of fission products with A>150, relative to that for thermal-neutron fission of²³⁵U, and the use of a relatively efficient ion source. Recent decay studies reported here include systematic measurements of rare-earth nuclide half-lives and comparison of them to theoretical prediction, a decay scheme investigation for¹⁵⁴Nd, and -strength function measurements for¹⁴⁰Cs.