Nucleus-nucleus reactions above TeV/amu region

This paper reports on transverse momenta of gamma rays and/or π0 mesons produced in high energy (approx-gt TeV/amu) cosmic ray nucleus-nucleus collisions measured with emulsion chambers. A group of events having large average transverse momenta, left-angle pT right-angle have been found, which exceed the apparent limiting behavior of left-angle pT right-angle. Analysis at the time of 1 fm/c indicates that the observed left-angle pT right-angle increased with both increasing energy density and rapidity density. A set of heavy-ion collision data have been analysed to examine the photon to hadron production rate in the forward pseudorapidity region, in terms of number ratio, RN and of momentum flow ratio, RM. With some photon-rich events, the isospin structures along the pseudorapidity axis were examined. The results implies that in the event-by-event basis, the local isospin conservation does not apparently hold, however the global ratio, by estimating the total number of photons from the momentum distribution could restore the symmetries except for some special events