First measurements of fundamental constants with a predictable photodiode cryogenic radiometer

This paper presents characterization of the first prototype of a predictable photodiode cryogenic radiometer (PPCR) at 77 K. The PPCR combines a predictable quantum efficiency detector (PQED) with a cryogenic radiometer (CR). When combining these two inherently different primary standards for measuring optical power on the same device, systematic error sources are eliminated, and the relationship between the elementary charge e and Planck´s constant h can be found from the modelled responsivity of the PQED. Our initial value deviates from the tabulated value of CODATA by 0.004%.