Development of a Novel AMS-14C Sample Preparation System

Abstract

A novel system for preparing 14C sample with various methods, including the zinc method, hydrogen method, and titanium hydride method, was developed for accelerator mass spectrometry (AMS) in 14C measurement. This sample preparation system consists of three units: vacuum maintenance unit, CO2 purification unit and CO2 reduction unit. All of the main structure is made of quartz glass. A series of 14C preparation experiment was carried out to verify the reliability of the system. The recovery rates of graphite obtained were more than 80%. The carbon content in the commercial toner and wood sample was linearly fitted to the CO2 pressure in the measurement unit of the system. A batch of standard samples, wood samples, and dead graphite samples made by this system was performed with AMS measurement. The results showed that the beam current of 12C- for each sample was greater than 20 μA. The measurement results of blank samples indicate the stability of the sample preparation system and the carbon pollution introduced during the sample preparation process was less than 5×10-15. The absolute AMS measurement value of modern wood samples is (9.13±0.05)×10-13, which consistents with the expected value ~9×10-13. All the results show that the novel sample preparation system established is a compact, low-pollution, efficient, and easy to operate system, which meets the AMS requirements for 14C samples.