AMS Measurement of 237Np at CIAE

237 Np (≃2.14 × 10 6 yr half-life) is potentially applicable in studies on nuclear safeguards and radioactive waste migration. The atomic ratio of 237 Np/U in nature is 10 −12 or even lower, depending strongly on the integral neutron flux received by the material. As an ultra-sensitive technique, accelerator mass spectrometry (AMS) is the best for measuring ultratrace 237 Np. By extracting negative molecular ions NpO – from the oxide sample using 238 UO – and 208 Pb 16 O 2 – pilot beams for the simulation of 237 Np ion transport, identifying the interference isotopes by high-resolution dedicated injector, electrostatic analyzer, and time of flight (TOF) detector, a method for AMS measurement of 237 Np was set up on the HI-13 accelerator at the China Institute of Atomic Energy (CIAE). A sensitivity of –11 has been achieved for the isotopic ratio 237 Np/ 238 U.