 Submillimeter APEX Bolometer Camera Bolometer Development Group Millimeter & Submillimeter Astronomy Group Max-Planck-Institut für Radioastronomie (MPIfR)
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Welcome to the official SABOCA website SABOCA ( Submillimeter APEX Bolometer Camera) is a multi-beam bolometric receiver developed by the Max-Planck-Institut für Radioastronomie (MPIfR) of Bonn SABOCA is a superconducting (TES) bolometer camera installed on the APEX telescope for operation in the 350 micron atmospheric window Bolometer Array
 The bolometers of SABOCA are composite bolometers with superconducting thermistors on structured membranes. The superconducting thermistors (called TES, Transition Edge Sensors) are bilayers of molybdenum and a gold-palladium alloy, deposited on the silicon-nitride membranes together with the niobium wiring and the radiation absorbing layer. IPHT has mastered to structure the membranes in order to control the thermal conductivity. Several layouts have been studied, with different membrane structures, thermistors and absorbing elements. The last generation of TES bolometers show reproducible, steep transitions and smooth load curves. The bolometers of SABOCA have moderately structured membranes and have shown a radiative NEP of 1.6 10-16 W/sqrt(Hz) (300 K background) during lab tests at MPIfR at a transition temperature of 0.45 K.  The array of SABOCA consists
of 39 TES bolometers. Of these, 37 are arranged in a hexagonal layout
consisting of a center channel and 3 concentric hexagons. Two
additional bolometers, identical to the inner 37 but optically not
coupled (called blind bolometers) were added to the layout at two
diametral opposite positions, for monitoring purposes. A monolithic array of conical horn antennas, placed in front of the bolometer wafer, concentrates the radiation onto the bolometers. 37 conical horns have been machined into a single aluminum block by the machine shop at MPIfR. In combination with the tertiary optics, the horn antennas are optimized for coupling to the telescope's main beam at a wavelength of 350 μm. Each horn antenna feeds into a circular wave guide acting as a high-pass filter. |
| web: gsiringo (at) mpifr-bonn.mpg.de | last edit: G. Siringo, MPIfR - February 2009 |