Dynamical emission and isotope thermometry

Ratios of the populations of ground and excited states of ⁴He, ⁵Li, and ⁸Be and double ratios constructed from the yields 3,4He, 6,7,8Li, 11,12,13C isotopes were measured for central Kr+Nb collisions at $E/A=35, 70, 100,$ 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 ⁴He, ⁵Li, and ⁸Be 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.