Design and performance of wide-band corrugated walls for the BICEP Array detector modules at 30/40 GHz

Abstract

BICEP Array is a degree-scale Cosmic Microwave Background (CMB) experiment that will search for primordial B-mode polarization while constraining Galactic foregrounds. BICEP Array will be comprised of four receivers to cover a broad frequency range with channels at 30/40, 95, 150 and 220/270 GHz. The first low-frequency receiver will map synchrotron emission at 30 and 40 GHz and will deploy to the South Pole at the end of 2019. In this paper, we give an overview of the BICEP Array science and instrument, with a focus on the detector module. We designed corrugations in the metal frame of the module to suppress unwanted interactions with the antenna-coupled detectors that would otherwise deform the beams of edge pixels. This design reduces the residual beam systematics and temperature-to-polarization leakage due to beam steering and shape mismatch between polarized beam pairs. We report on the simulated performance of single- and wide-band corrugations designed to minimize these effects. Our optimized design alleviates beam differential ellipticity caused by the metal frame to about 7% over 57% bandwidth (25 to 45 GHz), which is close to the level due the bare antenna itself without a metal frame. Initial laboratory measurements are also presented.

arXiv comment12 pages and 14 figures

References in corpus (8)

• BICEP2 I: Detection Of B-mode Polarization at Degree Angular Scales
• Benchmark Parameters for CMB Polarization Experiments
• BICEP2 / Keck Array VIII: Measurement of gravitational lensing from large-scale B-mode polarization
• BICEP2 / Keck Array V: Measurements of B-mode Polarization at Degree Angular Scales and 150 GHz by the Keck Array
• BICEP Array: a multi-frequency degree-scale CMB polarimeter
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Cited by in corpus (6)

• BICEP Array: a multi-frequency degree-scale CMB polarimeter
• 2017 upgrade and performance of BICEP3: a 95GHz refracting telescope for degree-scale CMB polarization
• Design and performance of the first BICEP Array receiver
• Optical characterization of the Keck Array and BICEP3 CMB Polarimeters from 2016 to 2019
• Optical Design and Characterization of 40-GHz Detector and Module for the BICEP Array
• Receiver development for BICEP Array, a next-generation CMB polarimeter at the South Pole