What primary calibration facilities exist in UK for cryogenic thermometers operating at temperatures down to 0.1K? (FAQ - Thermal)
The International Temperature Scale of 1990 goes down to 0.65 K, below this, to 1 mK, is the Provisional Low Temperature Scale of 2000 (PLTS-2000). NPL has a service to calibrate rhodium iron standard thermometers down to 0.65 K. As this is a specialised calibration it is done on a batch basis (occasionally other thermometers may be included). NPL also tries to maintain a stock of calibrated rhodium iron resistance thermometers for sale "off the shelf", but this depends on availability from the manufacturer.
Below 0.65 K there are currently no standard arrangements for calibration of cryogenic thermometers in the UK. NPL is presently developing such a facility as part of a EU Co-operative project with, among others, the PTB (German national standards laboratory), who already have a 1mK facility. It may also be possible to obtain commercial calibrations from Lakeshore Instruments, USA, for the range covered by dilution refrigerators; down to ~50 mK.