280 GHz Focal Plane Unit Design and Characterization for the SPIDER-2 Suborbital Polarimeter

Abstract

We describe the construction and characterization of the 280 GHz bolometric focal plane units (FPUs) to be deployed on the second flight of the balloon-borne SPIDER instrument. These FPUs are vital to SPIDER's primary science goal of detecting or placing an upper limit on the amplitude of the primordial gravitational wave signature in the cosmic microwave background (CMB) by constraining the B-mode contamination in the CMB from Galactic dust emission. Each 280 GHz focal plane contains a 16 x 16 grid of corrugated silicon feedhorns coupled to an array of aluminum-manganese transition-edge sensor (TES) bolometers fabricated on 150 mm diameter substrates. In total, the three 280 GHz FPUs contain 1,530 polarization sensitive bolometers (765 spatial pixels) optimized for the low loading environment in flight and read out by time-division SQUID multiplexing. In this paper we describe the mechanical, thermal, and magnetic shielding architecture of the focal planes and present cryogenic measurements which characterize yield and the uniformity of several bolometer parameters. The assembled FPUs have high yields, with one array as high as 95% including defects from wiring and readout. We demonstrate high uniformity in device parameters, finding the median saturation power for each TES array to be ~3 pW at 300 mK with a less than 6% variation across each array at one standard deviation. These focal planes will be deployed alongside the 95 and 150 GHz telescopes in the SPIDER-2 instrument, slated to fly from McMurdo Station in Antarctica in December 2018.

References in corpus (10)

• BICEP2 / Keck Array VI: Improved Constraints On Cosmology and Foregrounds When Adding 95 GHz Data From Keck Array
• BICEP2 II: Experiment and Three-Year Data Set
• SPIDER: Probing the Early Universe with a Suborbital Polarimeter
• Antenna-coupled TES bolometers used in BICEP2, Keck array, and SPIDER
• SPIDER: A Balloon-borne Large-scale CMB Polarimeter
• The Thermal Design, Characterization, and Performance of the SPIDER Long-Duration Balloon Cryostat
• Time-division SQUID multiplexers with reduced sensitivity to external magnetic fields
• Design and performance of the Spider instrument
• Design of 280 GHz feedhorn-coupled TES arrays for the balloon-borne polarimeter SPIDER
• Spider Optimization II: Optical, Magnetic and Foreground Effects

Cited by in corpus (5)

• SPIDER: CMB polarimetry from the edge of space
• Absolute calibration of the polarisation angle for future CMB $B$-mode experiments from current and future measurements of the Crab nebula
• Likelihood methods for CMB experiments
• Overview of the Medium and High Frequency Telescopes of the LiteBIRD satellite mission
• Crosstalk effects in microwave SQUID multiplexed TES bolometer readout