Owing to the dramatic change in the thermal conductivity of 4He when its temperature crosses the transition of superfluid (HeI) and normalfluid (HeII), a sealed-cell with a capillary is used to realize the lambda transition temperature, Tλ. A small heat flow is controlled through the capillary of the sealed-cell so as to realize the coexistence of HeI and HeII and maintain the stay of HeI/HeII interface in the capillary. A stable and flat lambda transition temperature "plateau" is obtained. Because there is a depression effect of Tλ caused by the heat flow through the capillary, a series of heat flows and several temperature plateaus are made and an extrapolation is applied to determine Tλ with zero heat flow. A rhodium-iron resistance thermometer with series number A34 (RIRT A34) has been used in 24 Tλ -realization experiments to derive Tλ with a standard deviation of 0.022mK, which proves the stability and reproducibility of Tλ.

JO - Metrology and Measurement Systems L1 - http://www.czasopisma.pan.pl/Content/89734/PDF/Journal10178-VolumeXVIII+Issue1_02+paper.pdf.pdf L2 - http://www.czasopisma.pan.pl/Content/89734 IS - No 1 EP - 24 KW - 4He KW - lambda transition temperature KW - sealed-cell KW - realization ER - A1 - Yin, L. A1 - Lin, P. A1 - Zhao, J. A1 - Qi, X. PB - Polish Academy of Sciences Committee on Metrology and Scientific Instrumentation JF - Metrology and Measurement Systems SP - 13 T1 - Analysis of the Factors Affecting the Realization of Lambda Transition Temperature of 4He UR - http://www.czasopisma.pan.pl/dlibra/docmetadata?id=89734 DOI - 10.2478/v10178-011-0002-7