The Simons Observatory: Design, Optimization, and Performance of Low-Frequency Detectors

Area of Science:

• Cosmology
• Astrophysics
• Detector Physics

Background:

• The Simons Observatory (SO) is a major cosmic microwave background (CMB) experiment in Chile.
• It aims for precise temperature and polarization measurements across six spectral bands (27-285 GHz).
• SO utilizes three small aperture telescopes (SATs) and one large aperture telescope (LAT) with approximately 60,000 detectors.

Purpose of the Study:

• To present the performance of low-frequency (LF) lenslet-coupled sinuous antenna transition-edge sensor (TES) bolometer arrays.
• To detail the design, optimization, and testing of pixels operating at 27 and 39 GHz.
• To highlight the role of these LF arrays in characterizing Galactic synchrotron emission for CMB foreground subtraction.

Main Methods:

• Development and testing of dichroic, lenslet-coupled sinuous antenna TES bolometer arrays.
• Focus on detector arrays operating at 27 and 39 GHz.
• Characterization of pixel performance for specific spectral bands.

Main Results:

• The study presents the performance of the LF bolometer arrays.
• Details on the design and optimization of the TES pixels are discussed.
• Current testing status of the detector arrays is provided.

Conclusions:

• The LF focal plane arrays are crucial for characterizing Galactic synchrotron emission.
• These measurements are critical for accurate foreground subtraction in CMB data.
• The presented detector technology is key to the Simons Observatory's scientific goals.