High-Level 14C Contamination and Recovery at Xi’an AMS Center

Abstract

A sample with a radiocarbon concentration estimated to be greater than 10⁵ times Modern was inadvertently graphitized and measured in the Xi’an AMS system last year. Both the sample preparation lines and the ion source system were seriously contaminated and a series of cleaning procedures were carried out to remove the contamination from them. After repeated and careful cleaning as well as continuous flushing with dead CO₂ gas, both systems have recovered from the contamination event. The machine background is back to 2.0 × 10^–16 and the chemical blank is beyond 50 kyr.

DOI: 10.2458/azu_js_rc.v54i2.16045