The AMS spectrometer “Compact Carbon AMS” (produced by NEC) was installed in the Poznan Laboratory in December 2001 (Goslar et al. 2004), and since then, it has made 14C measurements in ca. 12,000 graphite targets, mostly for 14C dating of natural samples. For the period of exploitation, the precision of the spectrometer has not deteriorated appreciably, and the machine background has stayed at roughly constant level. For all that time, the spectrometer has been operative almost continuously, and the longest period of inactivity was 7 days only, when a cooling fan failed inside the accelerator tank. Most periods of inactivity of the spectrometer (2-day long) were related to cleaning of the ion source, performed routinely after appearance of major instabilities of the source parameters. The durations of source performance after cleaning were very different (40-1600 measurements), and we note that they depend on individual specimen of the ionizer. The most distressing problems were the short-lasting instabilities of the accelerator voltage in March-June'03 and February'05, which, though slight, were precluding precise 14C measurements. We note that these problems were related with sputtering of aluminum from the cathode holders in the ion source, and they have been fixed by adjustments in the ion source, without opening the accelerator tank.
References: Goslar T., Czernik J., Goslar E., 2004. Low-energy 14C AMS in Poznan Radiocarbon Laboratory, Poland. Nuclear Instruments and Methods in Physics Research B, 223-224, 5-11.
See more of Poster Session I
See more of The 10th International Conference on Accelerator Mass Spectrometry (September 5-10, 2005)