Primary result of²³⁶U measurement with accelerator mass spectrometry at CIAE

Abstract：

The rare isotope²³⁶U has a half-life of 2.342(3)×10⁷years, and is produced principally by thermal neutron capture on²³⁵U. The isotopic atom ratio of²³⁶U/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 the²³⁶U¹⁶O^－beam transport with²³⁸U¹⁶O^－and²⁰⁸Pb₂¹⁶O^－pilot molecular ion beam, transporting the²³⁶U-containing ion beam with a high resolution injection magnet analyzer and electrostatic analyzer system, and finally identifying and detecting²³⁶U with a time-of-flight detector (TOF), a method for AMS (Accelerator Mass Spectrometry) measurement of²³⁶U was established on the HI-13 Accelerator AMS system at China Institute of Atomic Energy.