AKENO GIANT AIR SHOWER ARRAY (AGASA) COVERING 100 KM2 AREA

A very large surface array has been constructed recently at Akeno, 120 km west of Tokyo, to study the spectral features of the primary cosmic ray energy spectrum at the highest energies and to search for discrete sources emitting cosmic rays at energies above 10(17) eV. The new array, AGASA (Akeno Giant Air Shower Array) spread over an area of about 100 km2, consists of 111 scintillation detectors, each 2.2 m2 in area and 27 muon detectors of six different sizes. The distance between the detectors is about 1 km. The data acquisition network developed for AGASA links detectors with each other and with the four branch controllers with two optical-fiber cables for all communications. We present here the salient design features of AGASA and discuss the estimates of the accuracy in the determination of arrival direction and primary energy of showers expected to be achieved with AGASA.