BICEP Array: a multi-frequency degree-scale CMB polarimeter

TL;DR

BICEP Array is a multi-frequency CMB polarimeter with over 30,000 detectors designed to measure polarization and improve constraints on primordial gravitational waves, featuring advanced optics and modular design.

Contribution

It introduces a new multi-frequency instrument with upgraded detectors and modular focal planes, enhancing sensitivity for CMB polarization measurements.

Findings

First receiver at 30/40 GHz to observe at South Pole in 2019-20

Projected σ(r) of 0.003 for primordial gravitational waves

Over 30,000 detectors across four frequency bands

Abstract

BICEP Array is the newest multi-frequency instrument in the BICEP/Keck Array program. It is comprised of four 550 mm aperture refractive telescopes observing the polarization of the cosmic microwave background (CMB) at 30/40, 95, 150 and 220/270 GHz with over 30,000 detectors. We present an overview of the receiver, detailing the optics, thermal, mechanical, and magnetic shielding design. BICEP Array follows BICEP3's modular focal plane concept, and upgrades to 6" wafer to reduce fabrication with higher detector count per module. The first receiver at 30/40 GHz is expected to start observing at the South Pole during the 2019-20 season. By the end of the planned BICEP Array program, we project $\sigma(r) \sim 0.003$, assuming current modeling of polarized Galactic foreground and depending on the level of delensing that can be achieved with higher resolution maps from the South Pole Telescope.