Abstract

A 1.5 THz superconducting receiver has been in operation at the Receiver Lab Telescope of the Smithsonian Astrophysical Observatory in Northern Chile since December 2004. This receiver incorporates a Hot Electron Bolometer (HEB) mixer chip made from a thin film of Niobium Titanium Nitride (NbTiN), which is mounted in a precisionmachined waveguide mixer block attached to a corrugated waveguide horn assembly. With a noise temperature of around 1500 K, this receiver is sensitive enough for use in the pioneering field of ground-based terahertz spectral-line astronomy. A number of innovative techniques have been employed in the construction and deployment of this receiver. These include near-field vector beam mapping to enable accurate coupling to the telescope optics, the use of tunerless planar-diode based local oscillator unit capable of generating a few μW at 1.5 THz, and special calibration techniques required for terahertz astronomy. In this paper, we will report on the design, set-up and operation of this state-of-the-art instrument.