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Towards celestial sources above 1 THz with a heterodyne receiver based on a hot-electron bolometer mixer
Sergey Ryabchun, Ivan Tretyakov, Matvey Finkel, Natalia Kaurova, Boris Voronov and Gregory Gol'tsman
HOT-ELECTRON BOLOMETER (HEB) MIXER

Scient ific and Educatio nal Radiophysics Center Mo scow State Pedago gical University Mo scow, Russia

FIRST GROUND-BASED OBSERVATION WITH HEB MIXERS BEYOND 1 THz Submillimeter Telescope Observatory, the University of Arizona ­ elevation 3186 m, main reflector 10 m, frequency range 150 GHz ­ 1 THz

Electromagnetic radiation abso rbed by the film drives the superco nducting film o ut o f thermal equilibrium. Nonequilibrium ("hot") electrons are scattered by thermal vibrations of the lattice, which leads to the rise of the lattice (phonon) temperature. The lattice in its turn passes it on to the substrate. Besides interacting wit h the film phono ns, the nonequilibrium elect rons may diffuse out of the film into the co ntacts. Which of the two pro cesses will dominate depends o nly on the device geometry.

TERAHERTZ RADIATION IN SPACE = 30 m ­ 1 mm, = 300 GHz ­ 10 THz The terahertz region of the electromagnetic spectrum is emerging as an important field for o bservational astro nomy. Certain processes in the life cycle of the interstellar medium and galaxies have signature emissio n or absorption lines at terahertz frequencies. Hence, observations performed in the terahertz region may pro vide a deeper understanding o f the pheno mena which take place inside giant interstellar molecular clo uds and star formation regions, as well as informat ion abo ut various processes occurring in the Milky Way and in other galaxies. Observations in the terahertz region are quite challenging, primarily due to strong attenuation of elect romagnetic radiatio n of this frequency range by the earth's atmo sphere, which is why t elescopes have to be lo cated at high altitudes o r launched on board air- or spacecrafts.

plot taken from Dan Marrone et al., Observations in the 1.3 and 1.5 THz Atmospheric Windows with the Receiver Lab Telescope, in the Proc. 16th Int. Symp. on Space Terahertz Technology, Goteborg, Sweden, May 2005.

THE RECEIVER LAB TELESCOPE The Receiver Lab Telescope (RLT) is the first ground-based radio telescope designed for o peration at frequencies above 1 THz. It began observations fro m an altitude of 5525 meters (18,125 feet) on Cerro Sairecabur in nort hern Chile.
·main reflector diameter 80 cm ·frequency range 0.8 ­ 1.3 THz

C.E. Tong et al., Successful operation of a 1 THz NbN HotElectron Bolometer receiver, in the Proc. 11th Space THz Symposium, Ann Arbor, MI, pp. 49-59 (May 2000).
HOT-ELECTRON BOLOMETER MIXERS ON BOARD HERSCHEL The Euro pean Space Agency's Herschel Space Observatory (formerly called Far Infrared and Sub-millimetre Telescope or FIRST) has the largest single mirro r ever built for a space telescope. At 3.5-metres in diameter the mirror will co llect long-wavelength radiation from some of the coldest and mo st distant o bjects in the Universe. In addition, Herschel will be the only space observatory to cover a spectral range from the far infrared to sub-millimetre.
Heterodyne Instrument for the Far Infrared (HIFI): · H E B m ix e r s f o r 1 4 1 0 ­ 1 9 1 0 G H z · IF bandwidth 4 GHz
http://sci.esa.int/science-e/www/area/index.cfm?fareaid=16

plot taken from Dan Marrone et al., Observations in the 1.3 and 1.5 THz Atmospheric Windows with the Receiver Lab Telescope, in the Proc. 16th I nt. Symp. on Space Terahertz Technology, Goteborg, Sweden, May 2005.

MILLIMETRON ­ THE 12 m CRYOGENIC TELESCOPE FOR SINGLE DISH AND INTERFEROMETRY

The goal of the project is to construct a space observatory operating in the millimeter, sub-millimeter and infrared using 12-m cryogenic telescope in a single-dish mode and as an interferometer with the space-ground and space-space baselines (the later after the launch of the second identical space telescope). The observatory will allow conducting astronomical observations with super high sensitivity (down to nanoJansky level) in a single dish mode, and observations with high angular resolution in the interferometer mode.
· main reflector diameter 12 m, cooled to 4.2 K · HEB mixers for 1 ­ 6 THz

http://www.asc.rssi.ru/millimetron/eng/millim_eng.htm