Expanded array for giant air shower observation at Akeno

As the first stage of a future huge air shower array, the Akeno array was expanded to about 20 km2 by adding 19 scintillation counters of 2.25 m2 area outside the present 1 km2 array and installing a new data collection system. These detectors are connected successively by two optical fiber cables. The total number of electrons and the arrival direction of extensive air showers of 1010 GeV can be determined with accuracies of 25% and 30 respectively with this array. The present recording system is applicable to other experiments in which many sensors are connected in sequence. (orig.)