The single stage AMS machine at Lund University: Status report

In May 2003 Lund University, Sweden, ordered a new AMS facility from National Electrostatics Corp. (NEC), Wisconsin. The system is the first low energy, open air, single stage AMS system (SSAMS). The machine is equipped with a dual ion source sequential injector, which allows measurements of carbon with the masses 12, 13 and 14. The machine operates at 250 kV with the gas stripper, high energy magnet and detector mounted on a high voltage deck and with the injector at ground potential. The new machine was installed during August–October 2004 and about 500 samples were dated during the first nine months. The dual ion source injector allows both low-activity samples for radiocarbon dating and high-activity samples for medicine, biochemistry and ecology studies to be measured, with minimum risk of cross-contamination. The precision in radiocarbon dating is ±50 years or better and this is expected to improve with careful tuning of the machine. The background for processed graphite equates to about 43 000 radiocarbon years.