Quantum statistical thermodynamics of hot finite nuclear systems: Temperatures and isotopic yield ratios

We investigate the importance of the quantum statistics and deexcitation of primary fragments on the isotope yield ratio temperature determination. A phenomenological formula is presented which allows derivation of the temperature of the decaying nuclear system at the freeze-out time from the measured double yield ratios of two isotope pairs. This prescription is applied to the recent ALADIN and EOS Collaboration data. {copyright} {ital 1997} {ital The American Physical Society}