In-Flight Performance of Spider's 280 GHz Receivers

TL;DR

The paper evaluates the in-flight performance of SPIDER's 280 GHz detectors, a balloon-borne instrument for mapping cosmic microwave background polarization and Galactic dust, during its second Antarctic flight.

Contribution

It provides detailed analysis of the 280 GHz receivers' performance, including optical loading and detector noise, during SPIDER's second flight.

Findings

Successful operation of 280 GHz detectors in flight

Data on optical loading and noise levels obtained

Enhanced understanding of detector performance in balloon conditions

Abstract

SPIDER is a balloon-borne instrument designed to map the cosmic microwave background at degree-angular scales in the presence of Galactic foregrounds. SPIDER has mapped a large sky area in the Southern Hemisphere using more than 2000 transition-edge sensors (TESs) during two NASA Long Duration Balloon flights above the Antarctic continent. During its first flight in January 2015, SPIDER observed in the 95 GHz and 150 GHz frequency bands, setting constraints on the B-mode signature of primordial gravitational waves. Its second flight in the 2022-2023 season added new receivers at 280 GHz, each using an array of TESs coupled to the sky through feedhorns formed from stacks of silicon wafers. These receivers are optimized to produce deep maps of polarized Galactic dust emission over a large sky area, providing a unique data set with lasting value to the field. We describe the instrument's performance during SPIDER's second flight, focusing on the performance of the 280 GHz receivers. We include details on the flight, in-band optical loading at float, and an early analysis of detector noise.