A cryogenic rotation stage with a large clear aperture for the half-wave plates in the Spider instrument

Abstract

We describe the cryogenic half-wave plate rotation mechanisms built for and used in Spider, a polarization-sensitive balloon-borne telescope array that observed the Cosmic Microwave Background at 95 GHz and 150 GHz during a stratospheric balloon flight from Antarctica in January 2015. The mechanisms operate at liquid helium temperature in flight. A three-point contact design keeps the mechanical bearings relatively small but allows for a large (305 mm) diameter clear aperture. A worm gear driven by a cryogenic stepper motor allows for precise positioning and prevents undesired rotation when the motors are depowered. A custom-built optical encoder system monitors the bearing angle to an absolute accuracy of +/- 0.1 degrees. The system performed well in Spider during its successful 16 day flight.

11 pages, 7 figures, Published in Review of Scientific Instruments. v2 includes reviewer changes and longer literature review

References in corpus (9)

• Advanced ACTPol Cryogenic Detector Arrays and Readout
• CMBPol Mission Concept Study: Probing Inflation with CMB Polarization
• CLASS: The Cosmology Large Angular Scale Surveyor
• SPTpol: an instrument for CMB polarization measurements with the South Pole Telescope
• BICEP2 III: Instrumental Systematics
• Spider Optimization: Probing the Systematics of a Large Scale B-Mode Experiment
• The Thermal Design, Characterization, and Performance of the SPIDER Long-Duration Balloon Cryostat
• Pre-flight integration and characterization of the SPIDER balloon-borne telescope
• BLASTbus electronics: general-purpose readout and control for balloon-borne experiments

Cited by in corpus (16)

• The Cosmology Large Angular Scale Surveyor
• SPIDER: CMB polarimetry from the edge of space
• A New Limit on CMB Circular Polarization from SPIDER
• Exploring Cosmic Origins with CORE: The Instrument
• Design and development of an ambient-temperature continuously-rotating achromatic half-wave plate for CMB polarization modulation on the POLARBEAR-2 experiment
• A Large-Diameter Hollow-Shaft Cryogenic Motor Based on a Superconducting Magnetic Bearing for Millimeter-Wave Polarimetry
• A cryogenic continuously rotating half-wave plate for the POLARBEAR-2b cosmic microwave background receiver
• Impact of half-wave plate systematics on the measurement of cosmic birefringence from CMB polarization
• A large-diameter cryogenic rotation stage for half-wave plate polarization modulation on the POLARBEAR-2 experiment
• Systematic effects induced by Half Wave Plate precession into Cosmic Microwave Background polarization measurements
• Impact of half-wave plate systematics on the measurement of CMB $B$-mode polarization
• Measuring Reionization, Neutrino Mass, and Cosmic Inflation with BFORE
• Design and pre-flight performance of SPIDER 280 GHz receivers
• Consequences of constant elevation scans for instrumental systematics in Cosmic Microwave Background Experiments
• Modeling optical systematics for the Taurus CMB experiment
• In-Flight Performance of Spider's 280 GHz Receivers