4 He Gas in the Temperature-Range 1mK-5K: Thermodynamic Properties from the Quantum Second Virial Coefficient

Abstract

The quantum second virial coefficient Bq of low-dense 4He gas is calculated over the temperature-range 1 mK-5K. This is the first step in determining, according to standard expressions, the thermodynamic properties of the system, namely, the virial equation of state, compressibility factor, total internal energy, specific heat capacity, and entropy. These are compared to previous results wherever available. A large negative Bq is obtained. It is argued that this is intimately related to the formation of small clusters. Based on semi-quantitative analysis, the cluster formation is predicted to occur in the present system at a fairly low temperature ~ 0.049 K to 2.254 K.