Design and characterization of the SPT-3G receiver

Sobrin, J. A.; Ahmed, Zeeshan; Anderson, A. J.; Avva, J. S.; Thakur, R. Basu; Bender, A. N.; Benson, B. A.; Carlstrom, J. E.; Carter, F. W.; Cecil, T. W.; Chang, C. L.; Cliche, J. F.; Cukierman, A.; Haan, T. de; Ding, J.; Dobbs, M.; Dutcher, D.; Everett, W.; Foster, A.; Gallichio, J.; Gilbert, A.; Groh, J. C.; Guns, S.; Halverson, N. W.; Harke-Hosemann, A. H.; Harrington, N. L.; Henning, J. W.; Holzapfel, W. L.; Huang, N.; Irwin, K. D.; Jeong, O. B.; Jonas, M.; Khaire, T. S.; Kofman, A. M.; Korman, M.; Kubik, D. L.; Kuhlmann, S.; Kuo, Chao-Lin; Lee, A. T.; Lowitz, A. E.; Meyer, S. S.; Michalik, D.; Montgomery, J.; Nadolski, A.; Natoli, T.; Nguyen, H. T.; Noble, G. I.; Novosad, V.; Padin, S.; Pan, Z.; Pearson, John E.; Posada, C. M.; Quan, Wei; Rahlin, A.; Ruhl, J. E.; Sayre, J. T.; Shirokoff, E.; Smecher, G.; Stark, A. A.; Story, K. T.; Suzuki, Aritoki; Thompson, K. L.; Tucker, C.; Vanderlinde, K.; Vieira, J. D.; Wang, G.; Whitehorn, N.; Yefremenko, V.; Yoon, K. W.; Young, M. R.

doi:10.1117/12.2314366

Cited by 12 publications

(7 citation statements)

References 11 publications

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“…SPT-3G is a significant upgrade over the previous instruments, utilizing redesigned wide-field optics to increase the field of view from ∼1 deg 2 to 2.8 deg 2 and populating the 3.5× larger focal plane area with multichroic pixels. Light rays from the 10 m primary mirror are redirected by a 2 m ellipsoidal secondary mirror and 1 m flat tertiary mirror into the receiver cryostat [30], in which three 0.72 m diameter anti-reflection-coated alumina lenses [31] reimage the Gregorian focus onto the detectors. The SPT-3G receiver can be divided functionally into two cryostats that share a common vacuum: an optics cryostat that contains the cold optical elements, and a detector cryostat that contains the detectors and associated readout electronics.…”

Section: The Spt-3g Instrumentmentioning

confidence: 99%

Measurements of the E -mode polarization and temperature- E -mode correlation of the CMB from SPT-3G 2018 data

Dutcher¹,

Balkenhol²,

Ade³

et al. 2021

Phys. Rev. D

188

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We present measurements of the E-mode (EE) polarization power spectrum and temperature-E-mode (TE) cross-power spectrum of the cosmic microwave background using data collected by SPT-3G, the latest instrument installed on the South Pole Telescope. This analysis uses observations of a 1500 deg 2 region at 95, 150, and 220 GHz taken over a four-month period in 2018. We report binned values of the EE and TE power spectra over the angular multipole range 300 ≤ l < 3000, using the multifrequency data to construct six semi-independent estimates of each power spectrum and their minimum-variance combination. These measurements improve upon the previous results of SPTpol across the multipole ranges 300 ≤ l ≤ 1400 for EE and 300 ≤ l ≤ 1700 for TE, resulting in constraints on cosmological parameters comparable to those from other current leading ground-based experiments. We find that the SPT-3G data set is well fit by a ΛCDM cosmological model with parameter constraints consistent with those from Planck and SPTpol data. From SPT-3G data alone, we find H 0 ¼ 68.8 AE 1.5 km s −1 Mpc −1 and σ 8 ¼ 0.789 AE 0.016, with a gravitational lensing amplitude consistent with the ΛCDM prediction (A L ¼ 0.98 AE 0.12). We combine the SPT-3G and the Planck data sets and obtain joint constraints on the ΛCDM model. The volume of the 68% confidence region in six-dimensional ΛCDM parameter space is reduced by a factor of 1.5 compared to Planck-only constraints, with no significant shifts in central values. We note that the results presented here are obtained from data collected during just half of a typical observing season with only part of the focal plane operable, and that the active detector count has since nearly doubled for observations made with SPT-3G after 2018.

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Section: The Spt-3g Instrumentmentioning

confidence: 99%

Measurements of the E -mode polarization and temperature- E -mode correlation of the CMB from SPT-3G 2018 data

Dutcher¹,

Balkenhol²,

Ade³

et al. 2021

Phys. Rev. D

188

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“…With three generations of space mission, COBE, WMAP [5,6] and Planck [7,8], the accuracy of CMB measurement has been improved step by step, especially the temperature anisotropy, which has made a great contribution to pushing the study of modern cosmology into precision epoch. Now, CMB research is entering a new era, the socalled stage 3 [9][10][11][12], in which more detectors are planned for improving the sensitivity, and the key scientific goal is searching for primordial gravitational waves. Also, with the collaborative efforts of CMB-S4 [13,14], which are focused on ground-based CMB observations, the detector sensitivity on CMB will be logically improved ambitiously with at least ten times more detectors.…”

Section: Introductionmentioning

confidence: 99%

Detecting Primordial Gravitational Waves: a forecast study on optimizing frequency distribution of next generation ground-based CMB telescope

et al. 2020

Eur. Phys. J. C

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Probing primordial gravitational waves is one of the core scientific objectives of the next generation CMB polarization experiment. Integrating more detector modules on the focal plane and performing high accurate observations are the main directions of the next generation CMB polarization telescope, like CMB S4. Also, multi-band observation is required by foreground analysis and reduction, as it is understood that foregrounds have become the main obstacles of CMB polarization measurements. However, ground observation is limited by the atmospheric window and can be usually carried out in one or two bands, like what BICEP or Keck array have done in the south pole. In this paper, we forecast the sensitivity of tensor-to-scalar ratio r that may be achieved by a multi-frequency CMB polarization experiment, basing on which to provide guidance for further expanding frequency bands and optimize the focal plane of a telescope. At the same time, the realization of having two frequency bands in one atmospheric window is discussed. With fixed number of detectors, the simulation results show that, in order to get a good limit, more frequency bands are needed. Better constraints can be obtained when it includes at least three bands, i.e., one CMB channel (95 GHz) + one dust channel (high frequency) and one synchrotron channel (low frequency). For example, 41 + 95 + 220 GHz, which is better than only focusing around the CMB band, like 85 + 105 + 150 GHz, and 95 + 135 + 155 GHz, and this frequency combination is even better than the combination of 41 + 95 + 150 + 220 GHz. As CMB S4 plans to consider two frequency bands in each atmospheric window, and along this way, we find that one CMB band and more bands in synchrotron and dust channels are helpful, for example, 2 bands in lower frequency, 30 + 41 GHz, 2 bands in higher frequency, 220 + 270 GHz, i.e. 30 + 41

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“…Sapphire has 10% birefringence making it an ideal half-wave plate (HWP) material for polarimetric applications. A number of astrophysical instruments operating in the MSM waveband are using these materials [4][5][6][7] .…”

Section: Introductionmentioning

confidence: 99%

“…Two classes of MSM instruments that require broadbandwidths and cryogenic optical elements are those mapping the spatial polarization of the cosmic microwave background radiation (CMB) [5][6][7][10][11][12][13] , and others measuring the properties of Galactic dust [14][15][16] . A number of these instruments have used, or plan to use, sapphire as HWP polarization modulator.…”

Section: Introductionmentioning

confidence: 99%

Broadband, millimeter-wave anti-reflective structures on sapphire ablated with femto-second laser

Takaku,

Hanany,

Imada

et al. 2020

Preprint

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We designed, fabricated, and measured anti-reflection coating (ARC) on sapphire that has 116% fractional bandwidth and transmission of at least 97% in the millimeter wave band. The ARC was based on patterning pyramid-like subwavelength structures (SWS) using ablation with a 15 W femto-second laser operating at 1030 nm. One side of each of two discs was fabricated with SWS that had a pitch of 0.54 mm and height of 2 mm. The average ablation volume removal rate was 1.6 mm 3 /min. Measurements of the two-disc sandwich show transmission higher than 97% between 43 and 161 GHz. We characterize instrumental polarization (IP) arising from differential transmission due to asymmetric SWS. We find that with proper alignment of the two disc sandwich RMS IP across the band is predicted to be 0.07% at normal incidence, and less than 0.6% at incidence angles up to 20 degrees. These results indicate that laser ablation of SWS on sapphire and on other hard materials such as alumina is an effective way to fabricate broad-band ARC.

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Design and characterization of the SPT-3G receiver

Cited by 12 publications

References 11 publications

Measurements of the E -mode polarization and temperature- E -mode correlation of the CMB from SPT-3G 2018 data

Measurements of the E -mode polarization and temperature- E -mode correlation of the CMB from SPT-3G 2018 data

Detecting Primordial Gravitational Waves: a forecast study on optimizing frequency distribution of next generation ground-based CMB telescope

Broadband, millimeter-wave anti-reflective structures on sapphire ablated with femto-second laser

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