No abstract

The rare isotope 236U has a half-life of 2.342(3) × 107 years, and is produced principally by thermal neutron capture on 235U. The isotopic atom ratio of 236U/238U depends on the integral thermal neutron flux received by the material of interest. 236U is potentially useful as a “fingerprint" for indicating the presence of neutron-irradiated uranium usually originating from nuclear activity. By extracting negative molecular ion UO− from the uranium oxide target, simulating the 236U16O− beam transport with 238U16O− and 208Pb216O− pilot molecular ion beam, transporting the 236U-containing ion beam with a high resolution injection magnet analyzer and electrostatic analyzer system, and finally identifying and detecting 236U with a time-of-flight detector (TOF), a method for AMS (Accelerator Mass Spectrometry) measurement of 236U was established on the HI-13 Accelerator AMS system at China Institute of Atomic Energy.

No abstract

By using HPGe γ-ray spectrometry, the activity of the long-lived fission product 126Sn in a SnOB2 sample was measured. The number of 126Sn atoms and the ratio of 126Sn to Sn were calculated based on the half-life value of 2.35×105a and the chemical stoichiometry. The result of the ratio of 126Sn to Sn, (1.033±0.037)×10−8, is consistent with the results measured by the accelerator mass spectrometry (AMS) within uncertainty limits, which confirms our procedures in the measurement of 126Sn by AMS and lays a foundation for the AMS measurement of 126Sn at much lower levels.