Static operation of an AMS system using the beam monitor method

Abstract

The AMS system with a beam monitor method using the tandem accelerator of Tokyo University has been improved. The negative ion beam currents of two isotopes (or molecular ions) can be measured by two Faraday cups in order to monitor the fluctuation of the ion currents during the injection of the ions of interest into the tandem accelerator. The Faraday cups can be moved semiautomatically using computer-controlled stepping motors which search for the current peaks. Using these negative ion beam monitors and another one for accelerated positive ion currents, static operation of the whole system has become possible. The precision of measurements obtained by this method has been improved to ± 0.6% (1σ) for 10Be and 26Al-AMS and ±0.8% (1σ) for 14C-AMS.