Advanced ACTPol TES Device Parameters and Noise Performance in Fielded Arrays

TL;DR

This paper reports on the parameters and noise performance of aluminum manganese TES arrays used in the AdvACT upgrade of the Atacama Cosmology Telescope, highlighting their responsiveness and noise characteristics in fielded arrays for CMB observations.

Contribution

It provides detailed measurements of TES parameters, compares modeled and observed noise spectra, and presents noise performance data for multiple AdvACT arrays in laboratory and field conditions.

Findings

Detectors show high responsiveness with expected in-band noise levels.

Excess noise observed around 100 Hz, outside the main CMB signal band.

Full-array noise measurements demonstrate performance in both laboratory and field environments.

Abstract

The Advanced ACTPol (AdvACT) upgrade to the Atacama Cosmology Telescope (ACT) features arrays of aluminum manganese transition-edge sensors (TESes) optimized for ground-based observations of the Cosmic Microwave Background (CMB). Array testing shows highly responsive detectors with anticipated in-band noise performance under optical loading. We report on TES parameters measured with impedance data taken on a subset of TESes. We then compare modeled noise spectral densities to measurements. We find excess noise at frequencies around 100 Hz, nearly outside of the signal band of CMB measurements. In addition, we describe full-array noise measurements in the laboratory and in the field for two new AdvACT mid-frequency arrays, sensitive at bands centered on 90 and 150 GHz, and data for the high-frequency array (150/230 GHz) as deployed.