The POLARBEAR-2 and Simons Array Focal Plane Fabrication Status

Journal Article · Sat Dec 01 04:00:00 EST 2018 · Journal of Low Temperature Physics

DOI:https://doi.org/10.1007/s10909-018-2059-0· OSTI ID:1572524

Westbrook, B.; Ade, P. A. R.; Aguilar, M.; Aklba, Y.; Arnold, K.; Baccigalupi, C.; Barron, D.; Beck, D.; Beckman, S.; Bender, A. N.

We present on the status of POLARBEAR-2 A (PB2-A) focal plane fabrication. The PB2-A is the first of three telescopes in the Simons Array, which is an array of three cosmic microwave background polarization-sensitive telescopes located at the POLARBEAR site in Northern Chile. As the successor to the PB experiment, each telescope and receiver combination is named as PB2-A, PB2-B, and PB2-C. PB2-A and -B will have nearly identical receivers operating at 90 and 150 GHz while PB2-C will house a receiver operating at 220 and 270 GHz. Each receiver contains a focal plane consisting of seven close-hex packed lenslet-coupled sinuous antenna transition edge sensor bolometer arrays. Each array contains 271 dichroic optical pixels, each of which has four TES bolometers for a total of 7588 detectors per receiver. We have produced a set of two types of candidate arrays for PB2-A. The first we call Version 11 (V11) uses a silicon oxide (SiOx) for the transmission lines and crossover process for orthogonal polarizations. The second we call Version 13 (V13) uses silicon nitride (SiNx) for the transmission lines and cross-under process for orthogonal polarizations. We have produced enough of each type of array to fully populate the focal plane of the PB2-A receiver. The average wirebond yield for V11 and V13 arrays is 93.2% and 95.6%, respectively. The V11 arrays had a superconducting transition temperature (T-c) of 452 +/- 15 mK, a normal resistance (R-n) of 1.25 +/- 0.20 Omega, and saturation powers of 5.2 +/- 1.0 pW and 13 +/- 1.2 pW for the 90 and 150 GHz bands, respectively. The V13 arrays had a superconducting transition temperature (T-c) of 456 +/- 6 mK, a normal resistance (R-n) of 1.1 +/- 0.2 Omega, and saturation powers of 10.8 +/- 1.8 pW and 22.9 +/- 2.6 pW for the 90 and 150 GHz bands, respectively. Production and characterization of arrays for PB2-B are ongoing and are expected to be completed by the summer of 2018. We have fabricated the first three candidate arrays for PB2-C but do not have any characterization results to present at this time.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan; National Science Foundation (NSF); National Aeronautic and Space Administration (NASA); Simons Foundation; Natural Sciences and Engineering Research Council of Canada (NSERC); Japan Society for the Promotion of Science (JSPS); Chilean Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1572524
• Journal Information: Journal of Low Temperature Physics, Journal Name: Journal of Low Temperature Physics Journal Issue: 5-6 Vol. 193; ISSN 0022-2291
• Country of Publication: United States
• Language: English

Related Subjects

CMB
detectors
fabrication
inflation
instrumentation
polarization
sinuous antenna
transition edge sensor