New energy-spread-feedback control system using nondestructive energy-spread monitors

A new energy-spread feedback control system using nondestructive energy-spread monitors has been developed in order to control and stabilize the energy spreads of single-bunch electron and positron beams in the KEKB injector linac. A well-controlled feedback system has been successfully working in daily operation not only for keeping the injection rate higher along with the beam-orbit and energy-feedback control system, but also for reducing the background level to the KEKB collider experiment. The energy spreads of the injection beams have been well stabilized within 0:33 � 0:01% and 0:50 � 0:02% (0:55 � 0:06%) for the electron beam and the first (second) bunch of the high-current primary electron beam for positron production at the 180 � arc, respectively, and within 0:39 � 0:01% (0:36 � 0:03%) for the first (second) bunch of the positron beam at the end of the injector linac through the energy-spread feedback control system under the nominal operation condition. In this report we describe in detail the energyspread feedback control system using nondestructive energy-spread monitors with multi‐strip-line electrodes and their performance in KEKB operation.