Abstract
The resistance-temperature (R-T) characteristics of 1/8W Matsushita carbon resistors of grade ERC-18 SG (military grade) with the nominal values of 48, 82, 100, 220, and 330Ω have been measured in the region 4.2K-25mK and their usefulness as thermometers in this regionis confirmed. As to the 82Ω resistor, the measurement was extended to temperatures below 10mK. The temperature dependence of the resistance was found to be linear on the log-log plot over a wide range below 50mK. The sensitivity remains finite even at 6mK, but below 10mK rapid temperature measurements were prevented by a considerable increase in the thermal relaxation time. Measurements of the characteristics of some numbers of 100Ω resistors from each of two different lots showed that resistors from the same lot separate into two groups with different characteristics. This becomes appreciable with decreasing temperature below 4.2K, so that it is difficult to presume the behaviour of Matsushita resistors below 4.2K from the characteristics at higher temperatures, in contrast to the case of e.g. Speer resistors. The empirical formulae representing the R-T characteristics are discussed.
