Cryogen-free dilution refrigerator
Cool science below 100 mK at 5140 meters elevation!
Ultra-low temperature polarization-sensitive receiver for millimeter-wavelength Atacama Cosmology Telescope
JanisULT group is proud to announce that it has developed, in collaboration with multi-agency scientific collaboration team called ACTPol, a new pulse-tube cooled cryogenic platform for the Atacama Cosmology Telescope (ACT).
The ACT is a six-meter Gregorian telescope located at an altitude of 5,200 meters (17,000 ft) on Cerro Toco, in Northern Chile, and is dedicated to studies of the structure and evolution of the early universe through direct observation of the Cosmic Microwave Background (CMB) radiation at different polarizations and with arcminute resolution. Its new focal plane contains 3000 polarization-sensitive transition edge senor (TES) bolometers, which must be cooled to below 100 mK to work.
The new platform, together with new optical tubes and detectors developed by ACTPol collaboration, constitutes the telescope “light receiver” (camera). When fully deployed, its three light-sensing detector packages, as well as parts of the optical system, will be cooled by an integrated cryogen-free 3He – 4He dilution refrigerator developed by JanisULT. During its first season of operation in 2013, the first 150 GHz detector package array (PA1) was successfully tested on site and first light was received with detectors below 100 mK, which made this experiment the only CMB experiment to operate at such a low temperature.