Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

Abstract

The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe $\sim$70% of the sky. A variable-delay polarization modulator (VPM) modulates the polarization at $\sim$10 Hz to suppress the 1/f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that span both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single mode transmission on the chip and prevents stray light from coupling to the detectors.

arXiv comment7 pages, 5 figures, accepted by the Journal of Low Temperature Physics

References in corpus (7)

• CLASS: The Cosmology Large Angular Scale Surveyor
• The Cosmology Large Angular Scale Surveyor (CLASS): 40 GHz optical design
• The Cosmology Large Angular Scale Surveyor (CLASS): 38 GHz detector array of bolometric polarimeters
• Precision control of thermal transport in cryogenic single-crystal silicon devices
• Fabrication of Feedhorn-Coupled Transition Edge Sensor Arrays for Measurement of the Cosmic Microwave Background Polarization
• A waveguide-coupled thermally-isolated radiometric source
• Scalable background-limited polarization-sensitive detectors for mm-wave applications

Cited by in corpus (6)

• Four-year Cosmology Large Angular Scale Surveyor (CLASS) Observations: On-sky Receiver Performance at 40, 90, 150, and 220 GHz Frequency Bands
• Transition Edge Sensors: Physics and Applications
• Calibration of Transition-edge Sensor (TES) Bolometer Arrays with Application to CLASS
• Design and characterization of the Cosmology Large Angular Scale Surveyor (CLASS) 93 GHz focal plane
• On-sky performance of new 90 GHz detectors for the Cosmology Large Angular Scale Surveyor (CLASS)
• High-Efficiency and Low-Noise Detectors for the Upgraded CLASS 90 GHz Focal Plane