PRESENT STATUS OF TARN-II VACUUM-SYSTEM

The heavy ion cooler synchrotron, TARN-II, has been operated for studi es of accelerator technology and atomic physics since 1989 at the Inst itute for Nuclear Study, University of Tokyo. The ring has a circumfer ence of 78 m and the vacuum pipe is made of SUS 316L stainless steel T he vacuum system consists of ion pumps, titanium sublimation pumps and turbo-molecular pumps. Beam experiments like acceleration, electron c ooling, and extraction have been carried out at a mean pressure of the order of 10(-10) torr. In 199 1, the upgrading of TARN-II vacuum syst em had been performed by adding ion pumps and titanium sublimation pum ps in order to promote the experiments using heavy ion beams. Ion beam s such as p, D, H-2+, H-3+, He-3+, He-4(2+), HD2+, (HeH+)-He-4, N-14(5 +) and (N-14(7+) have been injected and circulated in the ring so far.