A Large Multiplate Cloud Chamber for Cosmic Ray Observation

A large multiplate cloud chamber has been constructed for the observation of the extensive air showers by extremely high energy cosmic radiations. Its dimensions of sensitive volume are 200 cm wide, 130 cm high and 90 cm deep. It contains 21 sheets of lead plate of 1 cm thick, so that the total thickness of the absorber corresponds to about 48 radiation length or about three times of nuclear interaction mean free path. The design and operational character are reported in this paper.