Liquid-vapor critical point ofHe4in aerogel

Thermodynamic studies of the liquid-vapor transition of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ confined in silica aerogel with a porosity of 95% is reported. In spite of the random nature of the pores, sharp heat-capacity signatures are seen. The positions of the sharp peaks are used to map out the liquid-vapor coexistence boundary, which is describable by a power law with an exponent β=0.28±0.05.