Ratios of the populations of ground and excited states of ${}^4\mathrm{He},$ ${}^5\mathrm{Li},$ and ${}^8\mathrm{Be}$ and double ratios constructed from the yields ${}^{3,4}\mathrm{He},$ ${}^{6,7,8}\mathrm{Li},$ ${}^{11,12,13}\mathrm{C}$ isotopes were measured for central Kr+Nb collisions at $E/A=35,\hspace{0.5em}70,\hspace{0.5em}100,$ and 120 MeV. These ratios were analyzed to estimate an apparent temperature for emission. Consistent and approximately constant apparent temperatures were obtained from the excited states of ${}^4\mathrm{He},$ ${}^5\mathrm{Li},$ and ${}^8\mathrm{Be}$ nuclei and from thermometers based upon the yields of carbon isotopes. In contrast, apparent temperatures obtained from thermometers based upon the ratios using helium isotopes increase monotonically with incident energy.

• Received 20 March 1998

DOI:https://doi.org/10.1103/PhysRevC.58.R2636