PRACTICE AND PROCEDURE OF THE MAINTENANCE FOR 
THE 12GeV-KEK-PS

Hikaru Sato and Tadamichi Kawakubo
Accelerator Laboratory, High Energy accelerator Organization (KEK),
Oho-1-1, Tsukuba-shi, Ibaraki-ken 305-0801, Japan

	The KEK-PS complex consists of four accelerators: two 750-keV Cockcroft-Walton pre-
injectors, a 40-MeV injector linac, a 500-MeV booster synchrotron and a 12-GeV main ring. 
Figure 1 shows a layout of the KEK-PS complex.  The slow beams are extracted to the east and 
north counter halls by a half integer resonance, and the internal target has also served the 
secondary beam in the east counter hall. Beam bunches accelerated in the booster except ones 
into the main ring are utilized in NML (Neutron and Meson Laboratory). We operate the 
machine for normally three weeks mode: 16 days operation and 5 days maintenance. For the 
need of longer utilizing time for the experiment, we are trying to operate a few months mode: 
composed of several parts of 19 days operation and two days conditioning time for the pre-
injector. We do the machine upgrades and the maintenance works, which need for a sufficient 
time, during a long summer shut down: typically two to three months. Staff grouping is 
organized depend on the machine maintenance except the beam handling group. We present the 
practice of the maintenance both of a preventative one and an accidental one, some other 
information for an operation procedure status and the practice of the upgrade project for the 
long-base-line nuetrino-oscillation experiment. 


                                     

Figure 1: Layout of the KEK-PS Complex.