Order in the concordance group and Heegaard Floer homology

We use the Heegaard-Floer homology correction terms defined by Ozsv\'{a}th--Szab\'{o} to formulate a new obstruction for a knot to be of finite order in the smooth concordance group. This obstruction bears a formal resemblance to that of Casson and Gordon but is sensitive to the difference between the smooth versus topological category. As an application we obtain new lower bounds for the concordance order of small crossing knots.