SINIS Detectors in the Subterahertz Range as a Basis for a Receiver for Radio Astronomical Research with the SAO RAS Optical Big Telescope Alt-Azimuth

Tarasov M. A.; Gunbina A. A.; Chekushkin A. M.; Markina M. A.; Yusupov R. A.; Fominskii M. Yu.; Filippenko L. V.; Edelman V. S.; Vdovin V. F.; Stolyarov V. A.; Zinchenko I. I.; Krasilnikov A. M.; Marukhno A. S.; Mansfeld M. A.; Kukushkin D. E.; Sazonenko D. A.; Bolshakov O. S.; Ermakov A. B.; Lesnov I. V.; Valeev, A. F.

There is an ongoing need in ground-based astronomy for ultra-sensitive receivers, both coherent (e.g., superheterodyne) and incoherent types, the latter offering potentially higher sensitivity. Both types rely on superconducting or cryogenically cooled semiconductor materials. This study explores the feasibility of using SINIS-based (Superconductor–Insulator–Normal metal–Insulator–Superconductor) detectors as incoherent superconducting receivers. We evaluate the ultimate performance parameters of SINIS detectors depending on the choice of superconducting material, operating temperature, and detection regime. Under moderate sub-Kelvin cooling (down to 0.28 K), aluminum-based SINIS detectors may achieve a responsivity of up to  10^8 V W^-1  and a noise-equivalent power NEP = 10^-17 W Hz^-1/2. For niobium-based SINIS detectors operating at 4.2 K, our estimates yield an NEP = 1.6 * 10^-16 W Hz^-1/2, which may be of practical interest for specific applications. At the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS), a prototype project is underway to develop a domestic subterahertz observatory module integrated with the Big Telescope Alt-azimuthal (BTA). Within this framework, a SINIS-based subterahertz receiver is planned to be installed at the Nasmyth focus of the BTA optical telescope. This paper provides a technical overview and proposed design of the SINIS receiver, taking into account the optical telescope’s reflective system architecture, its immediate environment, and the expected scientific goals of such an observational setup.