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Paper: ALMA: Exploring the Outer Limits of Redshift
Volume: 375, From Z-Machines to ALMA: (Sub)Millimeter Spectroscopy of Galaxies
Page: 191
Authors: Wootten, A.
Abstract: The Atacama Large Millimeter Array (ALMA)1 is a large international telescope project under construction in northern Chile on a site at Chajnantor of 5 km elevation. The excellent atmospheric transmission at that site in the millimeter and sub-millimeter wavelength ranges will allow ALMA to provide detailed images of the sources of the the cosmic microwave background and the cosmic far-infrared background radiation, near the wavelengths of the two strongest peaks in the spectral energy distribution of the universe. ALMA’s images will contain all of the flux in the imaged field through the use of two parts: (1) the “12m Array”, composed of up to 64 12m antennas that can be placed on 186 different stations for baselines up to 18 km (see Table 1), and (2) the “Atacama Compact Array” (ACA), which consists of 12 7m telescopes placed in compact configurations and four 12m telescopes for measuring source total power. At the shortest planned wavelength (λ = 0.3mm) and longest baseline, the angular resolution will be 0.004″. The receivers use superconducting (SIS) mixers, which– in combination with the excellent site transparency and the large array collecting area– will provide sensitivity at 1mm wavelength of 1mJy in a few seconds for average atmospheric conditions; this is more than two orders of magnitude better than any array operating today. At first light for the ALMA project, the six highest priority receiver bands will be installed, each observing both polarizations with a bandwidth of 8GHz.
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