The Atacama Cosmology Telescope (ACT) is a six-meter telescope located at an altitude of 5190 meters (17,028 ft) on Cerro Toco in the Atacama Desert in Chile. ACT was built to study the Cosmic Microwave Background (CMB) by taking surveys of the sky at microwave wavelengths. Three generations of cameras have been used with ACT, all relying on transition-edge-sensor (TES) bolometers, time-devision multiplexing (TDM) superconducting quantum interference devices (SQUIDs), and silicon lenses. The final camera, Advanced ACTPol (AdvACT) is currently being deployed at the site. AdvACT will map about half the sky in five frequency bands, from 28 to 230 GHz. It will map primary and secondary CMB anisotropies in intensity and polarization at a resolution of a few arcminutes, and will enable precision cosmological constraints as well as a wide array of cross-correlation science to probe the expansion history of the universe and the growth of large scale structure.
My work for ACT has involved a mix of device testing, remote observing, and data analysis. Using our lab’s dilution refrigerator and Multi-Channel Electronics (MCE) I screen SQUID multiplexing chips to be used in our TDM readout architecture. I’ve designed and built a secondary cryogenic testbed to house a pulse tube and expand our testing capabilities. I also analyze the maps that the ACT collaboration produces, working to extract thermal and kinematic Sunyaev-Zel’dovich signals from our images of the CMB. Finally, I work as a remote observer, taking 24-hour shifts of control over the telescope and coordinating with Team Toco down at the site.
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Header Image Credit: Mark Devlin/University of Pennsylvania