Receiver measurements at 1267 GHz using a diffusion-cooled superconducting transition-edge bolometer

We report receiver noise temperature measurements using a quasioptically coupled diffusion-cooled hot-electron bolometer mixer at a local oscillator frequency of 1267 GHz, and an intermediate frequency of 1.4 GHz. A best double-sideband (DSB) receiver noise temperature of 1880 K was measured, with an estimated mixer noise of 945 K (DSB), and a conversion efficiency including coupling losses of -19 dB (DSB). The coupled local oscillator power requirement for this device is estimated at roughly 6 nW. The mixer noise temperature is less than twice that measured earlier in a waveguide receiver at 530 GHz, which shows that the sensitivity of this type of mixer does not degrade sharply with increasing frequency in this regime.