Temperature determination from the lattice gas model

Determination of temperature from experimental data has become important in searches for critical phenomena in heavy-ion collisions. Widely used methods are ratios of isotopes (which rely on chemical and thermal equilibrium), population ratios of excited states, etc. Using the lattice gas model we propose a new observable: {ital n}{sub ch}/{ital Z} where {ital n}{sub ch} is the charge multiplicity and {ital Z} is the charge of the fragmenting system. We show that the reduced multiplicity is a good measure of the average temperature of the fragmenting system. {copyright} {ital 1996 The American Physical Society.}