Accelerator mass spectrometry at the University of Tokyo and its applications

In accelerator mass spectrometry (AMS), the sample to be analyzed itself is accelerated to form ion beams, and mass spectrometry is applied. Particularly with AMS, a very small amount of long half-life radioactive isotope can be measured with extremely high sensitivity. As the example of AMS measurement, this study firstly took up the measurement of ¹⁴C, which is the most widely used as a probe for dating, as well as the measurement of ¹⁰Be and ²⁶Al as examples. Then, it described the outline of AMS measurement using a tandem type electrostatic accelerator, which has many advantageous features for AMS. Today, tandem type electrostatic accelerator is used in AMS measurement in most cases. Finally, this paper reviewed the macro analysis laboratory tandem (MALT) accelerator of the Atomic Energy Research Center, University of Tokyo. The accelerator is pelletron type and acceleration voltage is maximum 5 MV. It is No. 1 unit that the USA NEC Corporation designed with consciousness of AMS. The incident analysis system is equipped with a sequential injection system that allows ions of different masses to be injected alternately, and the analysis system on the high energy side is equipped with a multi-Faraday cup system. At MALT, in addition to ¹⁴C - AMS, routine measurements of ¹⁰Be - AMS, ²⁶Al - AMS that are unique in Japan are carried out. In addition, MALT has multiple beam courses, and conducts the ultrafine analysis of elements using the methods other than AMS, as well as accelerator analysis research such as basic scientific experiments. (A.O.)