Large-PT spectrum of EAS subcores observed by the 54 m2 spark chamber array at Mt. Norikura

Extensive-air-shower subcores were observed by the 54 m2 spark chamber array at Mt. Norikura. The only subcores whose axes did not hit iron beams of the roof covering the array—34.6% of all the subcores we picked up—were analysed for estimation of PT against the EAS axis by comparing their lateral structures with Nishimura-Kidd's curves of electromagnetic-cascade showers induced by pair photons. The PT spectrum agrees with calculations applying QCD to large-PT jets in the collision energy at several hundred TeV. The ratio of the cross-section with PT≥15 GeV/c against the total inelastic one is 0.002.