APEX-SZ was a PI instrument that observed on the APEX telescope for a few weeks every year between 2007 and 2010. It's primary scientific goal was to measure galaxy clusters using the Sunyaev-Zel'dovich effect (SZE). In the SZE, cosmic microwave background photons scatter off the hot electrons in the intracluster medium and introduce a spectral shift. APEX-SZ observed at a frequency of 150 GHz where the SZE shows as a decrement compared to surrounding region. The integrated SZE flux can then be related to the total mass of the galaxy clusters, providing a means to measure the growth of structure in the universe by tracing the clusters.
The APEX-SZ receiver hosted what would be considered a small focal plane by current standards, with 280 spiderweb TES bolometers.
The APEX telescope is sited on the Chajnantor plateau of the Atacama Desert in Northern Chile. The high alitude (~5100 meters) and dryness of the Atacama desert provides excellent conditions for millimeter-wavelength observations. The primary mirror has a diameter of 12 meters.
The APEX-SZ receiver installed in the Cassegrain cabin of the telescope. Light is coupled into the receiver from a mirror at the bottom left up through optics and into the spiderweb bolometer detectors in the middle of the blue cyrostat.
Looking at the expose inside of the APEX-SZ cryostat during on of our detector upgrades. In the center is an array of feedhorns that couple the light down onto the individual bolometers underneath.
