Simple specific heat apparatus based on Gifford-Mac Mahon cryocooler

A simple apparatus for fast specific heat measurements between 15 and 300 K is presented. It consists of a sample holder embedded into a temperature-c ontrolled cell coupled to a Gifford-Mac Mahon cryocooler. We used two inexp ensive thin-him Pt-resistors electrically connected in series. One of them, weakly coupled to the cell by four measurement wires, acts as the sample h older, its thermometer, as well as its heater. The second one, located on t he cell, is used for temperature control in which a simple proportional-int egral control algorithm maintains the temperature difference between the sa mple holder and the cell within a few millikelvins. Our results for the spe cific heat of copper were obtained at sweep rates up to 200 K/h, and they m atch the tabulated values within 5%. (C) 2000 Elsevier Science B.V. All rig hts reserved.