STATUS REPORT ON THE DEVELOPMENT OF A SUPERCONDUCTIVE REFERENCE DEVICE FOR PRECISION THERMOMETRY BELOW 1 K

摘要

A Superconductive Reference Device (SRD1000), including 10 to 12 reference points in the temperature range 10 mK - 1 K and dedicated measurement electronics, is being developed to provide a direct and accurate traceability to the new Provisional Low Temperature Scale (PLTS-2000). In this paper we describe the preparation and the analysis of bulk samples of Ir_xRh_(100-x) alloys (showing transition temperatures T_c between 15 mK and 100 mK), single crystals of AuIn_2 (T_c = 160 mK), AuAl_2 (T_c = 208 mK) and Zn (T_c = 850 mK). The use of Mo/Au and Ti/Au bilayers as reference materials is proposed. Results of low temperature acceptance tests on best samples obtained are presented. The acceptance tests were performed in order to select the reference materials that are to be included in future pilot series SRD devices.