South Pole Telescope
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The South Pole Telescope or (SPT) is a project to build a submillimetre telescope at the South Pole. The telescope will have a 10 meter diameter primary mirror and is specifically designed to conduct large area millimeter and sub-millimeter wavelength surveys to map anisotropies in the cosmic microwave background radiation. The first key project for the SPT will be a 4000 square degree survey at wavelengths between 1-3 mm to search for clusters of galaxies via the Sunyaev-Zel'dovich effect (SZE), a technique which has been successfully demonstrated using the Arcminute Microkelvin Imager and the Sunyaev-Zel'dovich Array. This survey should find several thousand clusters of galaxies out to a redshift of about 2, and its goal is to place significant constraints on the equation of state of Dark Energy, a mysterious component of the universe which dominates its total energy density but is only detectable through its gravitational influence on visible matter.
The project is a collaboration between the University of Chicago, the University of California, Berkeley, Case Western Reserve University, the University of Illinois at Urbana-Champaign, and the Smithsonian Astrophysical Observatory. It is funded for 18 million dollars by the National Science Foundation. The telescope is scheduled to be completed by January 2007, with science observations planned to begin soon after.
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The telescope is a 10 meter off-axis Gregorian telescope in an Altazimuth mount. It has been designed to allow a large field of view (about 1 square degree) while minimizing systematic uncertainties from ground spill-over and scattering off the telescope optics. The surface accuracy of the telescope will be better than 20 micrometers, which will allow sub-millimeter wavelength observations.
The camera for the SPT will be a superconducting Transition Edge Sensor (TES) bolometer array with 1000 pixels, which will make it one of the largest TES bolometer array ever built. Bolometers are thermodynamic detectors that measure heat. They consist of an absorbing substrate attached to a variable resistor whose resistance will change depending on the amount of incident radiation/light on the substrate. The bolometers for the SPT are sensitive enough to measure temperature differences on the sky of 10 millionths of a degree. The SPT camera will be one of the first bolometer arrays built to take advantage of modern thin-film deposition and optical lithography techniques, which have been essential in the push towards large format arrays in millimeter wavelength astronomy.
The SPT project will be unique in that it will conduct one of the largest and deepest sky surveys to date at these wavelengths at one of the premier sites for millimeter wavelength astronomy, the South Pole.
