Apparatus for thermal diffusivity measurements in an extended temperature range

We present an improved ac method to measure the thermal diffusivity in an extended range of temperatures (15-330 K) and magnetic fields (0-8 T). We solder wires of a selected material directly on the sample: so, the thermal sensor is the junction between the sample and the wire. We have verified that this fast thermocouple works at frequencies high enough to neglect thermal losses also at the highest temperatures. Moreover, the soldered wires allow a concurrent four-wire resistivity measurement on the sample itsel