UC San Diego

The Simons Array is a polarization-sensitive cosmic microwave background (CMB) experiment located in the Atacama Desert in northern Chile. Observations of the CMB, which consists of the oldest observable light in the universe, have been invaluable for cosmological research in recent decades, producing a wealth of information regarding the universe's beginning and evolution, and providing substantial evidence in support of the Lambda-Cold Dark Matter model of cosmology. The field continues to grow as technological advances enable ever more sensitive measurements of both the intensity and polarization patterns imprinted in the CMB. The Simons Array aims to further our understanding of cosmology by measuring the polarization pattern of the CMB at angular scales ranging from a few arcminutes to a few degrees, with a focus on the faint B-mode polarization signals predicted at these scales.

The Simons Array is composed of three identical telescopes, each coupled to a cryogenic receiver. The receivers are developed and characterized in laboratories before installation at the observatory site in Chile at an altitude of 5,200 m, with significant upgrades compared to POLARBEAR-1, the Simons Array's predecessor, to improve the experiment's sensitivity. In particular, the upgraded receivers employ larger focal planes with increased detector counts and sensitivity across multiple frequency bands. This dissertation describes the Simons Array experiment as a whole, with an emphasis on the telescope accessories and laboratory characterization of the POLARBEAR-2b receiver, the second receiver of the Simons Array.