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The probability that a nucleus will absorb a neutron--the neutron capture cross-section--is important to many areas of nuclear science, including stellar nucleosynthesis, reactor performance, nuclear medicine and defence applications. Although neutron capture cross-sections have been measured for most stable nuclei, fewer results exist for radioactive isotopes, and statistical-model predictions typically have large uncertainties.sup.1. There are almost no nuclear data for neutron-induced reactions of the radioactive nucleus .sup.88Zr, despite its importance as a diagnostic for nuclear security. Here, by exposing .sup.88Zr to the intense neutron flux of a nuclear reactor, we determine that .sup.88Zr has a thermal neutron capture cross-section of 861,000 [plus or minus] 69,000 barns (1[sigma] uncertainty), which is five orders of magnitude larger than the theoretically predicted value of 10 barns.sup.2. This is the second-largest thermal neutron capture cross-section ever measured and no other cross-section of comparable size has been discovered in the past 70 years. The only other nuclei known to have values greater than 10.sup.5 barns.sup.3-6 are .sup.135Xe (2.6 × 10.sup.6 barns), a fission product that was first discovered as a poison in early reactors.sup.7,8, and .sup.157Gd (2.5 × 10.sup.5 barns), which is used as a detector material.sup.9,10, a burnable reactor poison.sup.11 and a potential medical neutron capture therapy agent.sup.12. In the case of .sup.88Zr neutron capture, both the target and the product (.sup.89Zr) nuclei are radioactive and emit intense [gamma]-rays upon decay, allowing sensitive detection of miniscule quantities of these radionuclides. This result suggests that as additional measurements with radioactive isotopes become feasible with the operation of new nuclear-science facilities, further surprises may be uncovered, with far-reaching implications for our understanding of neutron capture reactions.The thermal neutron capture cross-section of .sup.88Zr is measured to be 861,000 [plus or minus] 69,000 barns, the second-largest neutron capture cross-section ever measured., Author(s): Jennifer A. Shusterman [sup.1] [sup.2] [sup.3] , Nicholas D. Scielzo [sup.1] , Keenan J. Thomas [sup.1] , Eric B. Norman [sup.4] , Suzanne E. Lapi [sup.5] , C. Shaun [...]

The probability that a nucleus will absorb a neutron—the neutron capture cross-section—is important to many areas of nuclear science, including stellar nucleosynthesis, reactor performance, nuclear medicine and defence applications. Although neutron capture cross-sections have been measured for most stable nuclei, fewer results exist for radioactive isotopes, and statistical-model predictions typically have large uncertainties1. There are almost no nuclear data for neutron-induced reactions of the radioactive nucleus 88Zr, despite its importance as a diagnostic for nuclear security. Here, by exposing 88Zr to the intense neutron flux of a nuclear reactor, we determine that 88Zr has a thermal neutron capture cross-section of 861,000 ± 69,000 barns (1σ uncertainty), which is five orders of magnitude larger than the theoretically predicted value of 10 barns2. This is the second-largest thermal neutron capture cross-section ever measured and no other cross-section of comparable size has been discovered in the past 70 years. The only other nuclei known to have values greater than 105 barns3-6 are 135Xe (2.6 × 106 barns), a fission product that was first discovered as a poison in early reactors7,8, and 157Gd (2.5 × 105 barns), which is used as a detector material9,10, a burnable reactor poison11 and a potential medical neutron capture therapy agent12. In the case of 88Zr neutron capture, both the target and the product (89Zr) nuclei are radioactive and emit intense γ-rays upon decay, allowing sensitive detection of miniscule quantities of these radionuclides. This result suggests that as additional measurements with radioactive isotopes become feasible with the operation of new nuclear-science facilities, further surprises may be uncovered, with far-reaching implications for our understanding of neutron capture reactions. The thermal neutron capture cross-section of 88Zr is measured to be 861,000 ± 69,000 barns, the second-largest neutron capture cross-section ever measured. [ABSTRACT FROM AUTHOR]