Vacuum system of damping ring in KEK linear collider test facility

As the future plan of high energy elementary particle experiment, there is the Japan linear collider (JLC) project. This is to accelerate electrons and positrons up to 750 GeV with a linear accelerator, and by colliding them head on, to study on 1.5 TeV elementary particle reaction. As for linear colliders, it is advantageous that the background of reaction is very little, and the more clear and precision study can be realized. In order to realize this linear collider, the further research and development of accelerators are indispensable, and at present the construction of the accelerator test facility is in progress in KEK. It is expected to start the operation in 1994. The outline of the ATF is explained. The realization of ultralow emittance beam is the objective of the damping ring. The state of emittance due to the collision of beam with residual gas is explained. The design of the vacuum chamber is described on the wiggler and the deflection chamber, the vacuum components and so on. The effect of synchrotron radiation on chamber temperature and pressure is shown. (K.I.)