Simons Observatory Focal-Plane Module: In-lab Testing and Characterization Program

TL;DR

This paper details the testing and characterization procedures for the SO focal-plane modules, crucial for ensuring the performance of the large array of detectors in the cosmic microwave background experiment.

Contribution

It introduces a high-throughput validation program for the SO modules, including methods for measuring yield, noise, and optical efficiency, with initial results from prototypes.

Findings

Preliminary validation results demonstrate module performance.

Testing methods effectively assess yield and noise properties.

Initial prototypes meet expected performance criteria.

Abstract

The Simons Observatory (SO) is a ground-based cosmic microwave background instrument to be sited in the Atacama Desert in Chile. SO will deploy 60,000 transition-edge sensor bolometers in 49 separate focal-plane modules across a suite of four telescopes covering three dichroic bands termed low frequency (LF), mid frequency (MF) and ultra-high frequency (UHF). Each MF and UHF focal-plane module packages 1720 optical detectors and corresponding 100 mK microwave SQUID multiplexing readout components. In this paper we describe the testing program we have developed for high-throughput validation of the modules after they are assembled. The validation requires measurements of the yield, saturation powers, time constants, noise properties and optical efficiencies. Additional measurements will be performed for further characterizations as needed. We describe the methods developed and demonstrate preliminary results from initial testing of prototype modules.