Universality in fragment inclusive yields from Au + Au collisions

Abstract

The inclusive light fragment (Z ≤ 7) yield data in Au+Au reactions, measured by the EOS Collaboration at the LBNL Bevalac, are presented and discussed. For peripheral collisions the measured charge distributions develop progressively according to a power law which can be fitted by a single r exponent independently of the bombarding energy in the range 250-1200 A MeV. In addition to this universal feature, we observe that the location of the maximum in the individual yields of different charged fragments shift towards lower multiplicity as the fragment charge increases from Z = 3 to Z = 7. This trend is common to all six measured beam energies. Finally, a monotonic increase is observed in the THe,DT thermometer, built from double yield ratios. We find that our data bring additional experimental evidence of a liquid - gas phase transitions in nuclei, already reported by the EOS Collaboration for the Au -t C reaction.