Momentum Distribution in LiquidHe4atT=1.1 and 4.2K

A new analysis of neutron-scattering results for liquid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, which reduces the effects of interference and final-state interactions, yields model-independent results for the momentum distribution function, $n\left(\overrightarrow{\mathrm{p}}\right)$. At $T=4.2\mathrm{}$ K, $n\left(\overrightarrow{\mathrm{p}}\right)$ is found to be Gaussian but at $T=1.1\mathrm{}$ K it has an exponential tail at large $p$ and is enhanced near $p=0\mathrm{}$. An analysis of the temperature change in $n\left(\overrightarrow{\mathrm{p}}\right)$ gives a value of (6.9 ± 0.8)% for the condensate fraction at $T=1.1\mathrm{}$ K.