Year two instrument status of the SPT-3G cosmic microwave background receiver

TL;DR

This paper reports on the current status of the SPT-3G receiver, a high-resolution CMB instrument with advanced detector technology, after initial implementation and optimization efforts since its 2017 deployment.

Contribution

It provides an update on the technological implementation and performance status of the SPT-3G receiver, highlighting recent modifications for optimization.

Findings

Successful deployment of 16,000 polarization-sensitive bolometers

Implementation of advanced detectors, readout electronics, and optics

Ongoing optimization of instrument performance

Abstract

The South Pole Telescope (SPT) is a millimeter-wavelength telescope designed for high-precision measurements of the cosmic microwave background (CMB). The SPT measures both the temperature and polarization of the CMB with a large aperture, resulting in high resolution maps sensitive to signals across a wide range of angular scales on the sky. With these data, the SPT has the potential to make a broad range of cosmological measurements. These include constraining the effect of massive neutrinos on large-scale structure formation as well as cleaning galactic and cosmological foregrounds from CMB polarization data in future searches for inflationary gravitational waves. The SPT began observing in January 2017 with a new receiver (SPT-3G) containing $\sim$16,000 polarization-sensitive transition-edge sensor bolometers. Several key technology developments have enabled this large-format focal plane, including advances in detectors, readout electronics, and large millimeter-wavelength optics. We discuss the implementation of these technologies in the SPT-3G receiver as well as the challenges they presented. In late 2017 the implementations of all three of these technologies were modified to optimize total performance. Here, we present the current instrument status of the SPT-3G receiver.