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TT: Fachverband Tiefe Temperaturen

TT 19: Symposium “Terahertz Detectors”

TT 19.5: Vortrag

Mittwoch, 28. März 2007, 16:30–17:00, H20

Terahertz Bolometer Arrays for APEX — •Ernst Kreysa — MPIfR, Bonn, D

The Atacama Pathfinder Experiment (APEX) is a new terahertz telescope in the southern hemisphere. It is situated at an altitude of 5100 m, on Llano de Chajnantor in the Chilean Andes, where the atmospheric transmission is superb during a significant fraction of the year. The site is so dry that observations in the atmospheric window at 1.5 THz are feasible. With a diameter of 12 m and a surface of 18 micron rms, APEX is presently the most powerful terahertz telescope. At the Cassegrain focus, its field of view extends to about half a degree, making it very suitable for large scale mapping. The challenge for large terahertz bolometer arrays at APEX is that the Cassegrain cabin is so small. It also has only limited access and will tilt in elevation during observations. Sub-Kelvin cryogenic coolers or cryostats have to work under these conditions reliably and remotely. A first generation instrument, the large bolometer camera (LABOCA-1) with 295 bolometers for 345 GHz is being commissioned. While LABOCA-1 is still based on semiconductor thermistors, there can be no doubt that for really large arrays, superconducting bolometers with multiplexed SQUID readout are required. This new technology is being demonstrated with a small array of 40 bolometers for 0.85 THz. Results of these developments, carried out in cooperation between the Max-Planck-Institute for Radioastronomy (MPIfR) in Bonn and the Institute for Physical High Technology (IPHT) in Jena, will be presented.