Measurement of the decay of fission products for nuclear forensics

Detection of fission products (FPs) is at the basis of several applications, from reactor science, to non-proliferation and nuclear forensics. In most cases, an accurate quantification of FPs is only possible when the decay data of these isotopes - such as half-life, characteristic gamma-ray energies and intensities - are well known. This is not always the case, and - for many FPs - the current knowledge of decay data comes from measurements that were performed when gamma-ray spectroscopy was in its infancy.

The National Nuclear Data Center at Brookhaven National Laboratory, is pursuing a campaign to precisely determine gamma-ray intensities of selected FPs. In this work, we present the results for La-140 and Ce-143, two fission products of particular interest for nuclear forensics.

Both isotopes were produced via thermal neutron irradiation of natural samples of lanthanum and cerium at the University of Massachusetts Research Reactor, and assayed at Florida State University, using the Clarion2 array. The results of precision intensities measurements and updated decay schemes will be presented.