Fission Spectrometer For Individual Fragments Correlated With Gamma-rays

For safeguards, it is important to identify nuclear materials, and to enable that it is important to know what the signatures of the materials are. We are improving data on fission yields, with associated gammas in the prompt and delayed (>50ns) range. We are correlating the gamma rays with individually identified fission products in nearly independent yields (again >50ns). This work provides important data sets for not only safeguards but stockpile stewardship and fission theory. We developed an E-v fission spectrometer at UNM that measures both energy and velocity particle-by-particle to extract mass. The energy detector, a coaxial ionization chamber (IC), is operated as a time projection chamber to determine the depth of penetration of the fragments, from that, we can extract the Z information of the products. Tagging of prompt, quasi-prompt and delayed gamma-rays is implemented at the fission source and near the IC. The prompt gamma-rays detected near the source give an immediate response when a fission event takes place and can be associated with the production of an identified fragment. Gamma-ray detectors near the IC give us timing and spectra >50 ns after the fission event takes place. These can then be used in coincidence with direct product measurements from the ToF and IC to generate very clear gamma-ray spectra. We are working with 252Cf sources at UNM. At the LANSCE facility at LANL we will study correlated fission data with 235U and 239Pu targets over a range of neutron energies.