Advanced ACTPol Cryogenic Detector Arrays and Readout

TL;DR

Advanced ACTPol is a sophisticated upgrade to the Atacama Cosmology Telescope, featuring new cryogenic detector arrays and readout systems to enhance measurements of the cosmic microwave background for cosmological research.

Contribution

This paper introduces the design and implementation of advanced cryogenic detector arrays and readout architecture for the upgraded ACTPol instrument.

Findings

Deployment of four multichroic cryogenic arrays

Implementation of a 64-row multiplexing readout system

Enhanced sensitivity and resolution in CMB mapping

Abstract

Advanced ACTPol is a polarization-sensitive upgrade for the 6 m aperture Atacama Cosmology Telescope (ACT), adding new frequencies and increasing sensitivity over the previous ACTPol receiver. In 2016, Advanced ACTPol will begin to map approximately half the sky in five frequency bands (28-230 GHz). Its maps of primary and secondary cosmic microwave background (CMB) anisotropies -- imaged in intensity and polarization at few arcminute-scale resolution -- will enable precision cosmological constraints and also a wide array of cross-correlation science that probes the expansion history of the universe and the growth of structure via gravitational collapse. To accomplish these scientific goals, the Advanced ACTPol receiver will be a significant upgrade to the ACTPol receiver, including four new multichroic arrays of cryogenic, feedhorn-coupled AlMn transition edge sensor (TES) polarimeters (fabricated on 150 mm diameter wafers); a system of continuously rotating meta-material silicon half-wave plates; and a new multiplexing readout architecture which uses superconducting quantum interference devices (SQUIDs) and time division to achieve a 64-row multiplexing factor. Here we present the status and scientific goals of the Advanced ACTPol instrument, emphasizing the design and implementation of the Advanced ACTPol cryogenic detector arrays.