Heat Capacity of a Strongly-Interacting Fermi Gas

We report on the measurement of the heat capacity for an optically-trapped, strongly-interacting Fermi gas of atoms. In the experiments, a precise input of energy to the gas is followed by single-parameter thermometry. The thermometry determines a temperature parameter $\tilde{T}$ from the best fit of a Thomas-Fermi distribution with a fixed Fermi radius to the spatial density of the cloud. At $\tilde{T}=0.33$, we observe a transition between two patterns of behavior: For $\tilde{T}=0.33-2.15$, we find that the heat capacity closely corresponds to that of a trapped normal Fermi gas of atoms with increased mass. At low temperatures $\tilde{T}=0.04-0.33$, the heat capacity clearly deviates from normal Fermi gas behavior.