BEAM POSITION MONITORING-SYSTEM AND COD CORRECTION AT THE COOLER SYNCHROTRON TARN-II

At the cooler-synchrotron TARN II, light- and heavy-ion beams are stor ed, electron-cooled and accelerated for the research of atomic physics and accelerator studies. In these experiments, the closed orbit disto rtion (GOD) correction system plays an important role for improving th e beam currents and lifetimes. In order to measure the position of a c irculating faint beam in the ring, we developed beam diagnostic device s of high sensitivity and low noise. The beam positions can be measure d with an accuracy of 0.3 mm at a circulating beam current of 1 mu A. It is the purpose of the present paper to describe details concerning the beam position monitor (BPM) system, an investigation of the sensit ivities of the BPM from the point of view the S/N ratio, the experimen tal results of a COD correction and measurements of the accelerator pa rameters, such as the chromaticity and dispersion using this system.