Temperatures of 0.5 K obtained by pumping He4

In a previous communication (Goldschvartz and van de Merwe. Cryogenics; 15: 153 (1975)) an He4 adsorption cryostat with a new geometry was described with which temperatures of the order of 0.65 K could be achieved. The present note gives the results obtained with a new liquid He4 adsorption cryostat following the same principle as the former but in which some improvements have been introduced. With this new cryostat temperatures of the order of 0.50 K and a rather higher cooling power were obtained. The general characteristic shape of the cooling process and the coding power of the cryostat are shown graphically. (U.K.)