The density maximum in liquid He4 and its relationship to the lambda point

The lambda point in liquid He-4 is a very well-established phenomenon. London, in 1938, suggested that the effect might be an example of Bose-Einstein condensation and it is this model that is generally accepted nowadays. There are, however, serious discrepancies between the theory and experimental results. Here we present an alternative model based on the existence of the density maximum in liquid He-4 near 2.18 K, that explains the anomaly in the specific heat capacity but does not have the failings of the BEC model. In addition the theory explains the occurrence of the density maximum in liquid He-4. (c) 2006 Elsevier B.V. All rights reserved.