Thermal conductivity and Kapitza boundary resistance of He-4 near T(gamma)

The preliminary results of high resolution measurements of the thermal conductivity of He-4 in a cell with a nominal 1 mm gap are reported and compared with previous results obtained with a 2 mm gap. The temperature dependence of the conductivity was found to be similar for both cells, indicating that size and boundary effects are well controlled. The detailed behavior of the Kapitza resistance just below T(gamma) is also reported.