The mystery of the totally-consumed target: Measuring the ⁸⁸Zr neutron-capture cross section

Neutron-capture reactions on radioactive Zr isotopes are of significant importance to the stockpile-stewardship program and to nuclear astrophysics. We performed the first measurement of the neutron-capture cross section of ⁸⁸Zr to address one of the gaps in this cross-section data. The ⁸⁸Zr was produced at the University of Alabama at Birmingham Cyclotron Facility, radiochemically purified and made into targets at LLNL, irradiated at the University of Missouri Research Reactor, and subsequently analyzed at LLNL using gamma-ray spectroscopy to quantify the ⁸⁸Zr and ⁸⁹Zr content of the sample. We determined that the measured neutron-capture cross section deviates substantially from the predicted value. As access to hard-to-produce radionuclides and neutron-irradiation capabilities improve, additional surprising neutron-capture cross sections may be discovered, furthering the understanding of the nuclear physics surrounding these occurrences.