The terahertz radiation detector, designed in Russia for observing protostellar clouds, is less thick than a human hair and must operate at temperatures close to absolute zero. Acting director Andrey Khudchenko told socialbites.ca about this. Head of ASC FIAN’s Terahertz Devices and Technologies Laboratory.
Mankind has mastered nearly all electromagnetic wave ranges, from radio waves that are miles long to gamma radiation with a wavelength of less than a nanometer. However, for a long time there was a “gap” in this spectrum – it was not possible to design sensitive and efficient devices operating in the terahertz range (about a millimeter wavelength). It is also millimeter waves that are suitable for observing interstellar dust and protostellar clouds. Now specialists of the Institute of Physics of the Academy of Sciences, for the first time in Russia, have made a detector for a frequency of 250 GHz, the sensitivity of which is close to the theoretical limit. Before reaching the sensing element, the radio waves must pass through a series of auxiliary devices.
“Whether from the lab or through the window, the signal comes from outside. Through a special window, radio waves enter. [охлаждаемый гелием] The cryostat then focuses a system of mirrors on the horn. This horn directs the entire signal to a small metal waveguide measuring 1×0.5 mm. The signal goes from the waveguide to the superconducting microcircuit containing the detector. The microcircuit has dimensions comparable to a human hair and with the help of microstrips [радиодеталь для передачи ЭМ-волн, — «Газета.Ru»] directs the radiation to the sensing element. It is a superconductor-insulator-superconductor tunnel junction with a tunnel barrier of about one micron in size and about one nanometer, respectively. It is he who catches all the external radiation, ”said Andrey Khudchenko.
Niobium, which is cooled down to 4 kelvins with the help of liquid helium, acts as a superconductor in the detector. This cold is necessary because objects above absolute zero have a level of excitation that creates noise. Therefore, the lower the operating temperature the better, and with further cooling (even below 4 degrees), the quality of the detector can potentially improve.
Basically, such a detector is needed to build powerful radio telescopes similar to the ALMA located in Chile. Such radio telescopes are needed to map the distribution of water in a galaxy and to observe interstellar matter, including studying the molecular clouds that form stars.