The Swedish Heterodyne Facility Instrument (SHeFI) was built by the GARD group at the Chalmers University, Sweden, with the Onsala Space Observatory. The SHeFI consisted of four wide-band heterodyne receiver channels for 230 GHz (APEX-1), 345 GHz (APEX-2), 460 GHz (APEX-3), and 1300 GHz (APEX-T2). All the bands were located inside a single closed-cycle cryostat which maintained the coldest part at a temperature close to 4 K. The first three bands for 230, 345, and 460 GHz employed superconductor-insulator-superconductor (SIS) mixers and behaved as single sideband receivers (SSB). The 1.3 THz band was built using hot electron bolometer (HEB) mixer technology and was a double sideband receiver (DSB).
SHeFI was installed and commissioned during the first quarter of 2008, replacing the APEX-2A receiver. The cryostat was placed in the facility position of the Nasmyth-A Cabin, where it remained for almost a decade as the only facility heterodyne receiver.
This versatile multi-band instrument was able to cover almost all weather conditions at Chajnantor and, as a facility instrument, has been used by the entire APEX community, from all different partners. To date, SHeFI at APEX has produced more than 200 scientific publications covering many different scientific topics. At the end of 2017, SHeFI was finally decommissioned, leaving space for newer instrumentation in the A-cabin.
Main reference about SHeFI:
V. Vassilev, D. Meledin, I. Lapkin, V. Belitsky, O. Nyström, D. Henke, A. Pavolotsky, R. Monje, C. Risacher, M. Olberg, M. Strandberg, E. Sundin, M. Fredrixon, S.-E. Ferm, V. Desmaris, D. Dochev, M. Pantaleev, P. Bergman, and H. Olofsson, ”Swedish heterodyne facility instrument for the APEX telescope”, Astronomy and Astrophysics, A&A 490, pp. 1157‑1163, 2008
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