Helium beam acceleration in the KEK proton synchrotron with a newly developed injection system for positive/negative ions

A helium beam has been successfully accelerated in the KEK 12 GeV proton synchrotron up to 23 GeV of the limiting energy of the main ring. The first physics experiment with a helium beam was carried out in April, 1994. Although a charge exchange injection of negative hydrogen ions has been used in the booster synchrotron, it cannot be applied to the injection of positive ions, such as helium ions. A newly developed injection system realized alternative use of both negative and positive ion injection schemes.