The POLARBEAR-2 and Simons Array Focal Plane Fabrication Status

Journal Article · Fri Sep 07 00:00:00 EDT 2018 · Journal of Low Temperature Physics

DOI:https://doi.org/10.1007/s10909-018-2059-0· OSTI ID:1526554

Westbrook, B.; Ade, P. A. R.; Aguilar, M.; Akiba, Y.; Arnold, K.; Baccigalupi, C.; Barron, D.; Beck, D.; Beckman, S.; Bender, A. N.; Bianchini, F.; Boettger, D.; Borrill, J.; Chapman, S.; Chinone, Y.; Coppi, G.; Crowley, K.; Cukierman, A.; de Haan, T.; Dünner, R. ; Dobbs, M.; Elleflot, T.; Errard, J.; Fabbian, G.; Feeney, S. M.; Feng, C.; Fuller, G.; Galitzki, N.; Gilbert, A.; Goeckner-Wald, N.; Groh, J.; Halverson, N. W.; Hamada, T.; Hasegawa, M.; Hazumi, M.; Hill, C. A.; Holzapfel, W.; Howe, L.; Inoue, Y.; Jaehnig, G.; Jaffe, A.; Jeong, O.; Kaneko, D.; Katayama, N.; Keating, B.; Keskitalo, R.; Kisner, T.; Krachmalnicoff, N.; Kusaka, A.; Le Jeune, M.; Lee, A. T.; Leon, D.; Linder, E.; Lowry, L.; Madurowicz, A.; Mak, D.; Matsuda, F.; May, A.; Miller, N. J.; Minami, Y.; Montgomery, J.; Navaroli, M.; Nishino, H.; Peloton, J.; Pham, A.; Piccirillo, L.; Plambeck, D.; Poletti, D.; Puglisi, G.; Raum, C.; Rebeiz, G.; Reichardt, C. L.; Richards, P. L.; Roberts, H.; Ross, C.; Rotermund, K. M.; Segawa, Y.; Sherwin, B.; Silva-Feaver, M.; Siritanasak, P.; Stompor, R.; Suzuki, A.; Tajima, O.; Takakura, S.; Takatori, S.; Tanabe, D.; Tat, R.; Teply, G. P.; Tikhomirov, A.; Tomaru, T.; Tsai, C.; Whitehorn, N.; Zahn, A.

The status of POLARBEAR-2 A (PB2-A) focal plane fabrication is discussed. 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 (SiO_x) for the transmission lines and crossover process for orthogonal polarizations. The second we call Version 13 (V13) uses silicon nitride (SiN_x) 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 Ω, 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±0.2Ω, 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: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1526554
• Journal Information: Journal of Low Temperature Physics, Vol. 193, Issue 5-6; ISSN 0022-2291
• Publisher: Springer
• Country of Publication: United States
• Language: English

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