Formation of a single-bunch beam in the booster synchrotron at SPring-8

In order to fill an radio frequency (rf) bucket with an electron beam in th e storage ring at SPring-8, an rf knockout system was installed in the boos ter synchrotron. With this system, the energy of the electron beam injected from the linac was increased from 1 to 8 GeV. The time width of multi-bunc h beams from the linac operated at 2856 MHz rf can be selected as 1 or 40 n s. The beam injected from the linac is distributed in rf buckets of the boo ster synchrotron operated at 508.58 MHz rf. To fill a single rf bucket with a beam, the rf knockout system is operated at a minimum beam energy of 1 G eV. By using the rf knockout system, the electron beam is effectively kept in a single rf bucket. Then the beam is injected into a targeted rf bucket in the storage ring with a precise timing system. The beam intensity of sat ellite rf buckets in the storage ring was measured with a photon counting m ethod and determined to be 10(-6) less than that of the main rf bucket. In this paper, we describe the rf knockout system installed in the booster syn chrotron. (C) 2000 Elsevier Science B.V. All rights reserved.