Helium-4 Bose fluids formed in one-dimensional 18 angstrom diameter pores

Bose fluids restricted in one dimension (1D) are realized by adsorbing He-4 atoms on the 1D pore walls with a diameter of about 18 Angstrom. The Bose fluid appears above an adsorbed amount after the pore walls are coated with the inert He-4 atoms. Heat capacity of the fluid was observed to have a te mperature-linear term at low temperatures. This corresponds to the phonon h eat capacity of the Bose fluid in the 1D pores. We estimate the phonon velo city and the interaction of the 1D Bose fluid.