Extraction of the condensate fraction from the momentum distribution in superfluidHe4

Hiigh-momentum neutron scattering data can be used to find the momentum distribution n(p) of atoms in superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. The analysis of these data is complicated because the momentum distribution of the noncondensate atoms has an anomalous contribution which depends on the presence of the Bose condensate. We discuss a new way of estimating this contribution and show that the resulting values of the condensate fraction $n_0$(T) are quite different from those given in the recent literature.