TY - THES TI - Mixed helium-3 - helium-4 calorimeter. Very low temperature calorimetry; Calorimetre mixte a helium-3 et helium-4. Calorimetrie a tres basse temperature AB - A description is given of a double-racket calorimeter using helium-4 and helium-3 as the cryogenic fluids and making it possible to vary the temperature continuously from 0.35 K to 4.2 K. By using an electric thermal regulator together with liquid hydrogen it is possible to extend this range up to about 30 K. In the second part, a review is made of the various, methods available for measuring specific heats. The method actually used in the apparatus previously described is described in detail. The difficulties arising from the use of an exchange gas for the thermal contact have been solved by the use of adsorption pumps. (author) [French] On decrit un calorimetre a double enceinte utilisant comme fluide cryogenique l'helium-4 et l'helium-3 et permettant de varier continuement la temperature de 0,35 K a 4,2 K. L'utilisation d'un regulateur thermique electrique ainsi que celle d'hydrogene, liquide permettent d'etendre cette gamme jusqu'a 30 K environ. Dans une deuxieme partie, on passe en revue les diverses methodes de mesure des chaleurs specifiques. La methode concrete utilisee dans l'appareil precedemment decrit est exposee en detail. Les difficultes inherentes a l'utilisation de gaz d'echange comme agent de contact thermique ont ete levees par la mise en oeuvre de pompes a adsorbant. (auteur) AU - "Testard, O [Commissariat a l'Energie Atomique, Saclay (France). Centre d'Etudes Nucleaires]" KW - "71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS" KW - "CALORIMETRY" KW - "CRYOGENIC FLUIDS" KW - "CRYOSTATS" KW - "DEWARS" KW - "HELIUM 3" KW - "HELIUM 4" KW - "SPECIFIC HEAT" KW - "THERMAL CONDUCTION" DO - https://doi.org/ UR - https://www.osti.gov/etdeweb/servlets/purl/20622001 PB - CY - France PY - 1966 DA - 1966-06-01 LA - French J2 - [] VL - C1 - CEA Saclay, 91 - Gif-sur-Yvette (France); Faculte des Sciences de l'Universite de Paris, Centre d'Orsay, 91 (France) C2 - C3 - CEA-R-3073 C4 - C5 - Available from INIS in electronic form L3 - Other Information: TH: These sciences; 11 refs; PBD: Jun 1966 ER -