Development of an ac-dc thermal converter at millivolt level operating at cryogenic temperature

A device for the measurements of ac-dc transfer difference at millivolt level is under development at IEN. In this device a Cr heater, Nb leads and a Nb transition edge thermometer have been deposited by evaporation on a silicon nitride (SiN) membrane. Analysis on the possible effects on the ac-dc transfer difference and first experimental tests show the possibility of high accuracy direct measurements at the level of 1 mV.