Friday 31 January 2025
The Simons Observatory, a cosmic microwave background (CMB) survey experiment located in Chile’s Atacama Desert, is gearing up for its next phase of observations. The observatory consists of three small aperture telescopes (SATs), each designed to search for primordial gravitational waves, which could provide evidence of inflation, the rapid expansion of space-time in the early universe.
The SATs are tailored to detect these faint signals by mapping 10% of the sky at a noise level of 2 μK-arcmin. The telescopes will observe mid-frequencies (93 and 145 GHz), ultra-high-frequencies (225 and 280 GHz), and low-frequencies (27 and 39 GHz). By combining data from these different frequency bands, scientists can subtract out foreground emissions from our own galaxy and other sources of interference.
The design of the SATs is highly sophisticated. Each telescope consists of a series of cryogenic components, including a pulse tube cooler and dilution refrigerator, which keep the optics tube at 1K and the focal plane at ∼100mK. The telescopes also feature a unique polarization calibration system using a sparse wire grid to reduce systematic errors.
The integration and testing process for the SATs has been extensive, involving mechanical, electrical, optical, and safety testing. The first SAT, SAT-MF1, has already completed its site preparations and is expected to start taking data in 2024. The second SAT, SAT-MF2, is currently being integrated at Lawrence Berkeley National Laboratory, while the third SAT, SAT-UHF, will be shipped to Chile by the end of November 2023.
The Simons Observatory aims to make accurate measurements of the CMB temperature and polarization, covering angular scales between one arcminute and tens of degrees. The project’s primary science goal is to measure the primordial tensor-to-scalar ratio (r) at a target level of σ(r) ≈0.003. This could provide valuable insights into the nature of dark matter and dark energy, as well as the properties of inflation.
The observatory’s instrumentation is designed to be modular, with interchangeable components allowing for easier maintenance and upgrades. The readout system, developed by SLAC National Accelerator Laboratory, uses microwave multiplexing to amplify signals from the detectors, enabling the simultaneous measurement of thousands of pixels.
As the Simons Observatory prepares to start taking data, scientists are eager to explore the mysteries of the early universe.
Cite this article: “Simons Observatory Prepares to Uncover Cosmic Secrets”, The Science Archive, 2025.
Cosmic Microwave Background, Simons Observatory, Primordial Gravitational Waves, Inflation, Small Aperture Telescopes, Cryogenic Components, Polarization Calibration, Dark Matter, Dark Energy, Tensor-To-Scalar Ratio, Microwave Multiplexing
