Primary result of 236U measurement with accelerator mass spectrometry at CIAE

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.