OBSERVATION OF ATTENUATION BEHAVIOR OF HADRONS IN EXTREMELY HIGH-ENERGY COSMIC-RAY INTERACTIONS - NEW HADRONIC STATE

Experimental results are presented on high energy cosmic-ray hadron in teractions recorded in homogeneous-type thick lead chambers (total thi ckness being 60 cm and 110 cm) exposed at the Pamirs (atmospheric dept h 595 g/cm(2)). High energy cosmic-ray hadron flux is measured. The at tenuation mean free path of the arriving cosmic-ray hadrons of E(h)((g amma)) greater than or equal to 6 TeV measured in the chamber is obtai ned as 252 +/- 30 g/cm(2) of lead. However, for the high energy hadron s (E(gamma) greater than or equal to 10 TeV) constituting cosmic-ray f amilies of the highest energy range, Sigma E(gamma)greater than or equ al to 700 TeV, which have been accumulated so far in the series exposu res at the Pamirs and analysed by MSU group, the attenuation mean free path of hadrons in lead has turned out to be as short as 170(-26)(+47 ) g/cm(2) with 95% CL by the maximum likelihood method. The present ex perimental result of such a short attenuation length of hadrons in cos mic-ray families is essentially consistent with that obtained for high energy hadrons (E(gamma) greater than or equal to 10 TeV) constitutin g the ''Chiron-type'' families of Sigma E(gamma) > 100 TeV in the Chac altaya two-storeyed chamber experiments. The anomalous transition char acteristics of high energy hadrons in lead is found and examples are p resented. The physical significance of the experimental results on ext remely high energy hadron interactions is discussed.