# Performance of Al-Mn Transition-Edge Sensor Bolometers in SPT-3G

## TL;DR

This paper evaluates the performance of Al-Mn transition-edge sensor bolometers in the SPT-3G receiver, highlighting their electrical, thermal, and optical characteristics, and addressing calibration systematic errors in CMB measurements.

## Contribution

It presents the first in-lab and on-sky performance results of Al-Mn TES bolometers in the SPT-3G, demonstrating their viability for CMB observations.

## Key findings

- Al-Mn TES bolometers show comparable or improved sensitivity.
- Calibration systematic errors are identified and corrected.
- Optical efficiency and noise performance are characterized.

## Abstract

SPT-3G is a polarization-sensitive receiver, installed on the South Pole Telescope, that measures the anisotropy of the cosmic microwave background (CMB) from degree to arcminute scales. The receiver consists of ten 150~mm-diameter detector wafers, containing a total of 16,000 transition-edge sensor (TES) bolometers observing at 95, 150, and 220 GHz. During the 2018-2019 austral summer, one of these detector wafers was replaced by a new wafer fabricated with Al-Mn TESs instead of the Ti/Au design originally deployed for SPT-3G. We present the results of in-lab characterization and on-sky performance of this Al-Mn wafer, including electrical and thermal properties, optical efficiency measurements, and noise-equivalent temperature. In addition, we discuss and account for several calibration-related systematic errors that affect measurements made using frequency-domain multiplexing readout electronics.