We demonstrate successful cooling of an X-ray transition-edge sensor (TES) using solid-state refrigerators based on normal-metal/insulator/superconductor (NIS) tunnel junctions. Above the TES transition temperature (Tc), we use Johnson noise thermometry to measure the cooling performance. In this regime, the NIS refrigerators cool the TES from 300 mK to 220 mK and from 220 mK to Tc = 160 mK. Below Tc, we clearly see cooling and observe that the operation of the NIS refrigerators introduces no detectable noise into the TES readout. However, due to the complicated thermal circuit, we are currently unable to quantify the cooling below Tc without further measurements.
Citation: Journal of Low Temperature Physics
Pub Type: Journals
NIS junction, Refrigeration, TES, Tunneling, X-ray detector