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Study of Terahertz Focal Plain Arrays

Final Report Summary - TFPA (Study of Terahertz Focal Plain Arrays)

This research project has been devoted to development of novel cryogenic Kinetic Inductance Detector (KID) technology. It enables Terahertz focal-plane arrays of much larger pixel counts than were available before, without sacrificing sensitivity. This is possible due to the much higher multiplexing ratio available from this technology, due to inherent frequency-domain multiplexing. These arrays will be applied as the basis of a new generation of astrophysical instrumentation, both on the ground and in space, with much faster mapping speeds than before.
During this research, we were able to design monolithic focal plane arrays up to 5 Kpixel per die, based on an antenna/lens combined pixel optical design. We built a 0.3-mK-level experimental cryogenic system which is capable of holding such large arrays. We used that system to measure performance and demonstrate sensitivity and operation of these arrays.
Furthermore, we were able to bring smaller KID arrays to an instrument at a telescope, first at the IRAM 30-m telescope at Pico Veletta in Spain, and then to the Atacama Pathfinder Experiment (APEX) 12-m telescope in the Chilean desert at 5000-m altitude. This activity clearly demonstrated the performance of this new technology in a real telescope environment with astronomical sources in the presence of atmospheric noise. We were able to make maps of extended sources and measure sky calibrators.
Following up this successful demonstration, we were able to develop large KID focal-plane arrays to be part of the APEX MKID camera (AMKID), developed by the Max Planck Institute for Radioastronomy. AMKID is the largest dual-band 350/850-GHz sub-mm camera to date, with a pixel count of more than 25000 pixels. We are happy to report that the full instrument operated successfully at the APEX telescope with sky data, having all KID focal plane arrays available. This happened just at the end of this research program. Development took less than 5 years, which is unprecedented for arrays of this size.