Development Toward a Ground-Based Interferometric Phased Array for Radio Detection of High Energy Neutrinos

The in-ice radio interferometric phased array technique for detection of high energy neutrinos looks for Askaryan emission from neutrinos interacting in large volumes of glacial ice, and is being developed as a way to achieve a low energy threshold and a large effective volume at high energies. The technique is based on coherently summing the impulsive Askaryan signal from multiple antennas, which increases the signal-to-noise ratio for weak signals. We report here on measurements and a simulation of thermal noise correlations between nearby antennas, beamforming of impulsive signals, and a measurement of the expected improvement in trigger efficiency through the phased array technique. We also discuss the noise environment observed with an analog phased array at Summit Station, Greenland, a possible site for an interferometric phased array for radio detection of high energy neutrinos.Comment: 13 Pages, 14 Figure

Design and Bolometer Characterization of the SPT-3G First-year Focal Plane

During the austral summer of 2016-17, the third-generation camera, SPT-3G, was installed on the South Pole Telescope, increasing the detector count in the focal plane by an order of magnitude relative to the previous generation. Designed to map the polarization of the cosmic microwave background, SPT-3G contains ten 6-in-hexagonal modules of detectors, each with 269 trichroic and dual-polarization pixels, read out using 68x frequency-domain multiplexing. Here we discuss design, assembly, and layout of the modules, as well as early performance characterization of the first-year array, including yield and detector properties.Comment: Conference proceeding for Low Temperature Detectors 2017. Accepted for publication: 27 August 201

Measurements of B-mode Polarization of the Cosmic Microwave Background from 500 Square Degrees of SPTpol Data

We report a B-mode power spectrum measurement from the cosmic microwave background (CMB) polarization anisotropy observations made using the SPTpol instrument on the South Pole Telescope. This work uses 500 deg$^2$ of SPTpol data, a five-fold increase over the last SPTpol B-mode release. As a result, the bandpower uncertainties have been reduced by more than a factor of two, and the measurement extends to lower multipoles: $52 < \ell < 2301$. Data from both 95 and 150 GHz are used, allowing for three cross-spectra: 95 GHz x 95 GHz, 95 GHz x 150 GHz, and 150 GHz x 150 GHz. B-mode power is detected at very high significance; we find $P(BB < 0) = 5.8 \times 10^{-71}$, corresponding to a $18.1 \sigma$ detection of power. An upper limit is set on the tensor-to-scalar ratio, $r < 0.44$ at 95% confidence (the expected $1 \sigma$ constraint on $r$ given the measurement uncertainties is 0.22). We find the measured B-mode power is consistent with the Planck best-fit $\Lambda$CDM model predictions. Scaling the predicted lensing B-mode power in this model by a factor Alens, the data prefer Alens = $1.17 \pm 0.13$. These data are currently the most precise measurements of B-mode power at $\ell > 320$.Comment: 16 pages, 4 figures, Submitted to PR

Measurements of B-mode polarization of the cosmic microwave background from 500 square degrees of SPTpol data

We report a B-mode power spectrum measurement from the cosmic microwave background (CMB) polarization anisotropy observations made using the SPTpol instrument on the South Pole Telescope. This work uses 500 deg² of SPTpol data, a five-fold increase over the last SPTpol B-mode release. As a result, the bandpower uncertainties have been reduced by more than a factor of two, and the measurement extends to lower multipoles: 52 < ℓ < 2301. Data from both 95 and 150 GHz are used, allowing for three cross-spectra: 95 GHz × 95 GHz, 95 GHz × 150 GHz, and 150 GHz × 150 GHz. B-mode power is detected at very high significance; we find P(BB < 0) = 5.8 × 10⁻⁷¹, corresponding to a 18.1σ detection of power. With a prior on the galactic dust from Planck, WMAP and BICEP2/Keck observations, the SPTpol B-mode data can be used to set an upper limit on the tensor-to-scalar ratio, r < 0.44 at 95% confidence (the expected 1σ constraint on r given the measurement uncertainties is 0.22). We find the measured B-mode power is consistent with the Planck best-fit Λ CDM model predictions. Scaling the predicted lensing B-mode power in this model by a factor A_(lens), the data prefer A_(lens) = 1.17 ± 0.13. These data are currently the most precise measurements of B-mode power at ℓ > 320

Optimal CMB Lensing Reconstruction and Parameter Estimation with SPTpol Data

We perform the first simultaneous Bayesian parameter inference and optimal reconstruction of the gravitational lensing of the cosmic microwave background (CMB), using 100 deg$^2$ of polarization observations from the SPTpol receiver on the South Pole Telescope. These data reach noise levels as low as 5.8 $\mu$K-arcmin in polarization, which are low enough that the typically used quadratic estimator (QE) technique for analyzing CMB lensing is significantly sub-optimal. Conversely, the Bayesian procedure extracts all lensing information from the data and is optimal at any noise level. We infer the amplitude of the gravitational lensing potential to be $A_\phi\,{=}\,0.949\,{\pm}\,0.122$ using the Bayesian pipeline, consistent with our QE pipeline result, but with 17\% smaller error bars. The Bayesian analysis also provides a simple way to account for systematic uncertainties, performing a similar job as frequentist "bias hardening," and reducing the systematic uncertainty on $A_\phi$ due to polarization calibration from almost half of the statistical error to effectively zero. Finally, we jointly constrain $A_\phi$ along with $A_{\rm L}$, the amplitude of lensing-like effects on the CMB power spectra, demonstrating that the Bayesian method can be used to easily infer parameters both from an optimal lensing reconstruction and from the delensed CMB, while exactly accounting for the correlation between the two. These results demonstrate the feasibility of the Bayesian approach on real data, and pave the way for future analysis of deep CMB polarization measurements with SPT-3G, Simons Observatory, and CMB-S4, where improvements relative to the QE can reach 1.5 times tighter constraints on $A_\phi$ and 7 times lower effective lensing reconstruction noise.Comment: 27 pages, 14 figures, accompanying software package available at https://cosmicmar.com/CMBLensing.j