Design and characterization of the Cosmology Large Angular Scale Surveyor (CLASS) 93 GHz focal plane

Abstract

The Cosmology Large Angular Scale Surveyor (CLASS) aims to detect and characterize the primordial B-mode signal and make a sample-variance-limited measurement of the optical depth to reionization. CLASS is a ground-based, multi-frequency microwave polarimeter that surveys 70% of the microwave sky every day from the Atacama Desert. The focal plane detector arrays of all CLASS telescopes contain smooth-walled feedhorns that couple to transition-edge sensor (TES) bolometers through symmetric planar orthomode transducer (OMT) antennas. These low noise polarization-sensitive detector arrays are fabricated on mono-crystalline silicon wafers to maintain TES uniformity and optimize optical efficiency throughout the wafer. In this paper, we discuss the design and characterization of the first CLASS 93 GHz detector array. We measure the dark parameters, bandpass, and noise spectra of the detectors and report that the detectors are photon-noise limited. With current array yield of 82%, we estimate the total array noise-equivalent power (NEP) to be 2.1 aW$\sqrt[]{\mathrm{s}}$.

arXiv comment16 pages, 9 figures

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Cited by in corpus (9)

• Four-year Cosmology Large Angular Scale Surveyor (CLASS) Observations: On-sky Receiver Performance at 40, 90, 150, and 220 GHz Frequency Bands
• The CLASS 150/220 GHz Polarimeter Array: Design, Assembly, and Characterization
• Two-year Cosmology Large Angular Scale Surveyor (CLASS) Observations: 40 GHz Telescope Pointing, Beam Profile, Window Function, and Polarization Performance
• On-sky performance of the CLASS Q-band telescope
• The Cosmology Large Angular Scale Surveyor Receiver Design
• Calibration of Transition-edge Sensor (TES) Bolometer Arrays with Application to CLASS
• Cosmology Large Angular Scale Surveyor (CLASS): 90 GHz Telescope Pointing, Beam Profile, Window Function, and Polarization Performance
• 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