71 research outputs found
Antenna-coupled TES bolometer arrays for CMB polarimetry
We describe the design and performance of polarization selective
antenna-coupled TES arrays that will be used in several upcoming Cosmic
Microwave Background (CMB) experiments: SPIDER, BICEP-2/SPUD. The fully
lithographic polarimeter arrays utilize planar phased-antennas for collimation
(F/4 beam) and microstrip filters for band definition (25% bandwidth). These
devices demonstrate high optical efficiency, excellent beam shapes, and
well-defined spectral bands. The dual-polarization antennas provide
well-matched beams and low cross polarization response, both important for
high-fidelity polarization measurements. These devices have so far been
developed for the 100 GHz and 150 GHz bands, two premier millimeter-wave
atmospheric windows for CMB observations. In the near future, the flexible
microstrip-coupled architecture can provide photon noise-limited detection for
the entire frequency range of the CMBPOL mission. This paper is a summary of
the progress we have made since the 2006 SPIE meeting in Orlando, FL
Antenna-coupled TES bolometer arrays for CMB polarimetry
We describe the design and performance of polarization selective
antenna-coupled TES arrays that will be used in several upcoming Cosmic
Microwave Background (CMB) experiments: SPIDER, BICEP-2/SPUD. The fully
lithographic polarimeter arrays utilize planar phased-antennas for collimation
(F/4 beam) and microstrip filters for band definition (25% bandwidth). These
devices demonstrate high optical efficiency, excellent beam shapes, and
well-defined spectral bands. The dual-polarization antennas provide
well-matched beams and low cross polarization response, both important for
high-fidelity polarization measurements. These devices have so far been
developed for the 100 GHz and 150 GHz bands, two premier millimeter-wave
atmospheric windows for CMB observations. In the near future, the flexible
microstrip-coupled architecture can provide photon noise-limited detection for
the entire frequency range of the CMBPOL mission. This paper is a summary of
the progress we have made since the 2006 SPIE meeting in Orlando, FL
SPIDER: CMB Polarimetry from the Edge of Space
Spider is a balloon-borne instrument designed to map the polarization of the millimeter-wave sky at large angular scales. Spider targets the B-mode signature of primordial gravitational waves in the cosmic microwave background (CMB), with a focus on mapping a large sky area with high fidelity at multiple frequencies. Spider ’s first long-duration balloon (LDB) flight in January 2015 deployed a total of 2400 antenna-coupled transition-edge sensors (TESs) at 90 GHz and 150 GHz. In this work we review the design and in-flight performance of the Spider instrument, with a particular focus on the measured performance of the detectors and instrument in a space-like loading and radiation environment. Spider ’s second flight in December 2018 will incorporate payload upgrades and new receivers to map the sky at 285 GHz, providing valuable information for cleaning polarized dust emission from CMB maps
280 GHz Focal Plane Unit Design and Characterization for the Spider-2 Suborbital Polarimeter
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 16×16 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 1530 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
A New Limit on CMB Circular Polarization from SPIDER
We present a new upper limit on cosmic microwave background (CMB) circular polarization from the 2015 flight of SPIDER, a balloon-borne telescope designed to search for B-mode linear polarization from cosmic inflation. Although the level of circular polarization in the CMB is predicted to be very small, experimental limits provide a valuable test of the underlying models. By exploiting the nonzero circular-to-linear polarization coupling of the half-wave plate polarization modulators, data from SPIDER's 2015 Antarctic flight provide a constraint on Stokes V at 95 and 150 GHz in the range 33 < ℓ < 307. No other limits exist over this full range of angular scales, and SPIDER improves on the previous limit by several orders of magnitude, providing 95% C.L. constraints on ℓ(ℓ + 1)C^(VV)_ ℓ/(2π) ranging from 141 to 255 μK^2 at 150 GHz for a thermal CMB spectrum. As linear CMB polarization experiments become increasingly sensitive, the techniques described in this paper can be applied to obtain even stronger constraints on circular polarization
SPIDER: a new balloon-borne experiment to measure CMB polarization on large angular scales
We describe SPIDER, a novel balloon-borne experiment designed to measure the polarization of the Cosmic Microwave Background (CMB) on large angular scales. The primary goal of SPIDER is to detect the faint signature of inflationary gravitational waves in the CMB polarization. The payload consists of six telescopes, each operating in a single frequency band and cooled to 4 K by a common LN/LHe cryostat. The primary optic for each telescope is a 25 cm diameter lens cooled to 4 K. Each telescope feeds an array of antenna coupled, polarization sensitive sub-Kelvin bolometers that covers a 20 degree diameter FOV with diffraction limited resolution. The six focal planes span 70 to 300 GHz in a manner optimized to separate polarized galactic emission from CMB polarization, and together contain over 2300 detectors. Polarization modulation is achieved by rotating a cryogenic half-wave plate in front of the primary optic of each telescope. The cryogenic system is designed for 30 days of operation. Observations will be conducted during the night portions of a mid-latitude, long duration balloon flight which will circumnavigate the globe from Australia. By spinning the payload at 1 rpm with the six telescopes fixed in elevation, SPIDER will map approximately half of the sky at each frequency on each night of the flight
Spider Optimization: Probing the Systematics of a Large Scale B-Mode Experiment
Spider is a long-duration, balloon-borne polarimeter designed to measure
large scale Cosmic Microwave Background (CMB) polarization with very high
sensitivity and control of systematics. The instrument will map over half the
sky with degree angular resolution in I, Q and U Stokes parameters, in four
frequency bands from 96 to 275 GHz. Spider's ultimate goal is to detect the
primordial gravity wave signal imprinted on the CMB B-mode polarization. One of
the challenges in achieving this goal is the minimization of the contamination
of B-modes by systematic effects. This paper explores a number of instrument
systematics and observing strategies in order to optimize B-mode sensitivity.
This is done by injecting realistic-amplitude, time-varying systematics in a
set of simulated time-streams. Tests of the impact of detector noise
characteristics, pointing jitter, payload pendulations, polarization angle
offsets, beam systematics and receiver gain drifts are shown. Spider's default
observing strategy is to spin continuously in azimuth, with polarization
modulation achieved by either a rapidly spinning half-wave plate or a rapidly
spinning gondola and a slowly stepped half-wave plate. Although the latter is
more susceptible to systematics, results shown here indicate that either mode
of operation can be used by Spider.Comment: 15 pages, 12 figs, version with full resolution figs available here
http://www.astro.caltech.edu/~lgg/spider_front.ht
SPIDER: a balloon-borne CMB polarimeter for large angular scales
We describe SPIDER, a balloon-borne instrument to map the polarization of the
millimeter-wave sky with degree angular resolution. Spider consists of six
monochromatic refracting telescopes, each illuminating a focal plane of
large-format antenna-coupled bolometer arrays. A total of 2,624 superconducting
transition-edge sensors are distributed among three observing bands centered at
90, 150, and 280 GHz. A cold half-wave plate at the aperture of each telescope
modulates the polarization of incoming light to control systematics. Spider's
first flight will be a 20-30-day Antarctic balloon campaign in December 2011.
This flight will map \sim8% of the sky to achieve unprecedented sensitivity to
the polarization signature of the gravitational wave background predicted by
inflationary cosmology. The Spider mission will also serve as a proving ground
for these detector technologies in preparation for a future satellite mission.Comment: 12 pages, 6 figures; as published in the conference proceedings for
SPIE Millimeter, Submillimeter, and Far-Infrared Detectors and
Instrumentation for Astronomy V (2010
Design and construction of a carbon fiber gondola for the SPIDER balloon-borne telescope
We introduce the light-weight carbon fiber and aluminum gondola designed for
the SPIDER balloon-borne telescope. SPIDER is designed to measure the
polarization of the Cosmic Microwave Background radiation with unprecedented
sensitivity and control of systematics in search of the imprint of inflation: a
period of exponential expansion in the early Universe. The requirements of this
balloon-borne instrument put tight constrains on the mass budget of the
payload. The SPIDER gondola is designed to house the experiment and guarantee
its operational and structural integrity during its balloon-borne flight, while
using less than 10% of the total mass of the payload. We present a construction
method for the gondola based on carbon fiber reinforced polymer tubes with
aluminum inserts and aluminum multi-tube joints. We describe the validation of
the model through Finite Element Analysis and mechanical tests.Comment: 16 pages, 11 figures. Presented at SPIE Ground-based and Airborne
Telescopes V, June 23, 2014. To be published in Proceedings of SPIE Volume
914
The Thermal Design, Characterization, and Performance of the SPIDER Long-Duration Balloon Cryostat
We describe the SPIDER flight cryostat, which is designed to cool six
millimeter-wavelength telescopes during an Antarctic long-duration balloon
flight. The cryostat, one of the largest to have flown on a stratospheric
payload, uses liquid helium-4 to deliver cooling power to stages at 4.2 and 1.6
K. Stainless steel capillaries facilitate a high flow impedance connection
between the main liquid helium tank and a smaller superfluid tank, allowing the
latter to operate at 1.6 K as long as there is liquid in the 4.2 K main tank.
Each telescope houses a closed cycle helium-3 adsorption refrigerator that
further cools the focal planes down to 300 mK. Liquid helium vapor from the
main tank is routed through heat exchangers that cool radiation shields,
providing negative thermal feedback. The system performed successfully during a
17 day flight in the 2014-2015 Antarctic summer. The cryostat had a total hold
time of 16.8 days, with 15.9 days occurring during flight.Comment: 15 pgs, 17 fig
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