In Situ Time Constant and Optical Efficiency Measurements of TRUCE Pixels in the Atacama B-Mode Search

• Published in: Journal of low temperature physics 2014-09, Vol.176 (5-6), p.712-718
• Main Authors: Simon, S. M., Appel, J. W., Cho, H. M., Essinger-Hileman, T., Irwin, K. D., Kusaka, A., Niemack, M. D., Nolta, M. R., Page, L. A., Parker, L. P., Raghunathan, S., Sievers, J. L., Staggs, S. T., Visnjic, K.
• Format: Article
• Language: English
• Subjects: ABS; Characterization and Evaluation of Materials; Condensed Matter Physics; Cosmic microwave background; Deserts; Low temperature physics; Magnetic Materials; Magnetism; Multiplexing; Physics; Physics and Astronomy; Pixels; Polarization; Searching
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-013-0999-y

The Atacama B-mode Search (ABS) instrument, which began observation in February of 2012, is a crossed-Dragone telescope located at an elevation of 5,100 m in the Atacama Desert in Chile. The primary scientific goal of ABS is to measure the B-mode polarization spectrum of the Cosmic Microwave Background from multipole moments of about ℓ ≈ 50 to ℓ ≈ 500 (angular scales from ∼ 0 . 4 ∘ to ∼ 4 ∘ ), a range that includes the primordial B-mode peak from inflationary gravitational waves. The ABS focal plane array consists of 240 pixels designed for observation at 145 GHz by the TRUCE collaboration. Each pixel has its own individual, single-moded feedhorn and contains two transition-edge sensor bolometers coupled to orthogonal polarizations that are read out using time domain multiplexing. We will report on the current status of ABS and discuss the time constants and optical efficiencies of the TRUCE detectors in the field.