Design and characterization of 90 GHz feedhorn-coupled TES polarimeter pixels in the SPTpol camera

TL;DR

This paper details the design and characterization of 90 GHz feedhorn-coupled TES polarimeter pixels for the SPTpol camera, aimed at studying faint polarization signals in the Cosmic Microwave Background.

Contribution

It introduces a new design and characterization methodology for 90 GHz TES polarimeter pixels used in the SPTpol instrument.

Findings

Successful fabrication of 90 GHz TES pixels

Performance characterization aligning with design expectations

Enhanced sensitivity for CMB polarization measurements

Abstract

The SPTpol camera is a two-color, polarization-sensitive bolometer receiver, and was installed on the 10 meter South Pole Telescope in January 2012. SPTpol is designed to study the faint polarization signals in the Cosmic Microwave Background, with two primary scientific goals. One is to constrain the tensor-to-scalar ratio of perturbations in the primordial plasma, and thus constrain the space of permissible inflationary models. The other is to measure the weak lensing effect of large-scale structure on CMB polarization, which can be used to constrain the sum of neutrino masses as well as other growth-related parameters. The SPTpol focal plane consists of seven 84-element monolithic arrays of 150 GHz pixels (588 total) and 180 individual 90 GHz single-pixel modules. In this paper we present the design and characterization of the 90 GHz modules.