Crystal Structure of Helium Isotopes

Abstract

The neutron diffraction data of Henshaw for crystalline ${\mathrm{He}}^4$ have been treated by the method of least squares to obtain revised values of the lattice constants and their standard errors. The values so obtained, together with the pressure-volume-temperature data of Dugdale and Simon, are used to make a direct comparison with the interatomic distances and molar volume for $\beta$-${\mathrm{He}}^3$, which is also hexagonal close-packed.