BREMSSTRAHLUNG PHOTONS AS A PROBE OF HOT NUCLEI

Aside from the dominant production of hard photons in first-chance p-n collisions, a significant hard-photon production in a later stage of heavy-ion reactions is predicted by the BUU theory. These thermal hard photons are emitted from a nearly thermalized source and still origin ate from bremsstrahlung produced in individual p-n collisions. The cal culations predict that the production of the thermal hard photons is s trongly correlated with the incompressibility of nuclear matter. Tenta tive experimental evidence for their production is found in the hard-p hoton energy spectra measured in the systems Kr-86 + Ni-nat at 60.0A M eV, Ta-181 + Au-197 at 39.5A MeV and (208)pb + Au-197 at 29.5A MeV.