A cryostat and temperature regulation system for very slow continuous cooling and heating experiments

A cryostat has been constructed and successfully used for neutron scattering experiments in the critical region of first order phase transitions. A massive copper sample-holder is suspended in a thermally well-insulated way within the temperature-regulated inner vessel of the cryostat. The temperature regulation is of a differential type. A certain temperature difference between the sample holder and the inner vessel, which determines the temperature variation rate, is maintained constant. Short-term temperature fluctuations of the inner vessel are not transmitted to the sample holder due to the large time constant of the system. The sample-holder temperature is measured by a platinum resistor and an ac-double bridge with a precision of 10-3 K. Temperature variation rates (slopes) typically range from 10-1 K to 10-3 K per hour. (Auth.)