-
R Dünner,
M Hasselfield,
T ~A Marriage,
J Sievers,
V Acquaviva,
G ~E Addison,
P ~A ~R Ade,
P Aguirre,
M Amiri,
J ~W Appel, [......],
S ~T Staggs,
D ~S Swetz,
E ~R Switzer,
R Thornton,
H Trac, C Tucker,
R Warne,
G Wilson,
E Wollack,
Y Zhao
apj. 01/2013; 762:10.
-
Z. Kermish,
P. Ade,
A. Anthony,
K. Arnold,
D. Barron,
D. Boettger,
J. Borrill,
S. Chapman,
Y. Chinone,
M. A. Dobbs, [......],
M. Sholl,
P. Siritanasak,
H. Spieler,
N. Stebor,
B. Steinbach,
R. Stompor,
A. Suzuki,
T. Tomaru, C. Tucker,
O. Zahn
[show abstract]
[hide abstract]
ABSTRACT: We present the design and characterization of the POLARBEAR experiment.
POLARBEAR will measure the polarization of the cosmic microwave background
(CMB) on angular scales ranging from the experiment's 3.5 arcminute beam size
to several degrees. The experiment utilizes a unique focal plane of 1,274
antenna-coupled, polarization sensitive TES bolometers cooled to 250
milliKelvin. Employing this focal plane along with stringent control over
systematic errors, POLARBEAR has the sensitivity to detect the expected small
scale B-mode signal due to gravitational lensing and search for the large scale
B-mode signal from inflationary gravitational waves.
POLARBEAR was assembled for an engineering run in the Inyo Mountains of
California in 2010 and was deployed in late 2011 to the Atacama Desert in
Chile. An overview of the instrument is presented along with characterization
results from observations in Chile.
10/2012;
-
K. Arnold,
P. A. R. Ade,
A. E. Anthony,
D. Barron,
D. Boettger,
J. Borrill,
S. Chapman,
Y. Chinone,
M. A. Dobbs,
J. Errard, [......],
M. Sholl,
P. Siritanasak,
H. Spieler,
N. Stebor,
B. Steinbach,
R. Stompor,
A. Suzuki,
T. Tomaru, C. Tucker,
O. Zahn
[show abstract]
[hide abstract]
ABSTRACT: The Polarbear Cosmic Microwave Background (CMB) polarization experiment is
currently observing from the Atacama Desert in Northern Chile. It will
characterize the expected B-mode polarization due to gravitational lensing of
the CMB, and search for the possible B-mode signature of inflationary
gravitational waves. Its 250 mK focal plane detector array consists of 1,274
polarization-sensitive antenna-coupled bolometers, each with an associated
lithographed band-defining filter. Each detector's planar antenna structure is
coupled to the telescope's optical system through a contacting dielectric
lenslet, an architecture unique in current CMB experiments. We present the
initial characterization of this focal plane.
10/2012;
-
K. Story,
E. Leitch,
P. Ade,
K. A. Aird,
J. E. Austermann,
J. A. Beall,
D. Becker,
A. N. Bender,
B. A. Benson,
L. E. Bleem, [......],
G. Smecher,
B. Stalder, C. Tucker,
K. Vanderlinde,
J. D. Vieira,
G. Wang,
R. Williamson,
V. Yefremenko,
K. W. Yoon,
E. Young
[show abstract]
[hide abstract]
ABSTRACT: We present the software system used to control and operate the South Pole
Telescope. The South Pole Telescope is a 10-meter millimeter-wavelength
telescope designed to measure anisotropies in the cosmic microwave background
(CMB) at arcminute angular resolution. In the austral summer of 2011/12, the
SPT was equipped with a new polarization-sensitive camera, which consists of
1536 transition-edge sensor bolometers. The bolometers are read out using 36
independent digital frequency multiplexing (\dfmux) readout boards, each with
its own embedded processors. These autonomous boards control and read out data
from the focal plane with on-board software and firmware. An overall control
software system running on a separate control computer controls the \dfmux
boards, the cryostat and all other aspects of telescope operation. This control
software collects and monitors data in real-time, and stores the data to disk
for transfer to the United States for analysis.
10/2012;
-
J. T. Sayre,
P. Ade,
K. A. Aird,
J. E. Austermann,
J. A. Beall,
D. Becker,
B. A. Benson,
L. E. Bleem,
J. Britton,
J. E. Carlstrom, [......],
E. Shirokoff,
K. Story, C. Tucker,
K. Vanderlinde,
J. D. Vieira,
G. Wang,
R. Williamson,
V. Yefremenko,
K. W. Yoon,
E. Young
[show abstract]
[hide abstract]
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.
10/2012;
-
J. W. Henning,
P. Ade,
K. A. Aird,
J. E. Austermann,
J. A. Beall,
D. Becker,
B. A. Benson,
L. E. Bleem,
J. Britton,
J. E. Carlstrom, [......],
E. Shirokoff,
K. Story, C. Tucker,
K. Vanderlinde,
J. D. Vieira,
G. Wang,
R. Williamson,
V. Yefremenko,
K. W. Yoon,
E. Young
[show abstract]
[hide abstract]
ABSTRACT: The SPTpol camera is a dichroic polarimetric receiver at 90 and 150 GHz.
Deployed in January 2012 on the South Pole Telescope (SPT), SPTpol is looking
for faint polarization signals in the Cosmic Microwave Background (CMB). The
camera consists of 180 individual Transition Edge Sensor (TES) polarimeters at
90 GHz and seven 84-polarimeter camera modules (a total of 588 polarimeters) at
150 GHz. We present the design, dark characterization, and in-lab optical
properties of the 150 GHz camera modules. The modules consist of
photolithographed arrays of TES polarimeters coupled to silicon platelet arrays
of corrugated feedhorns, both of which are fabricated at NIST-Boulder. In
addition to mounting hardware and RF shielding, each module also contains a set
of passive readout electronics for digital frequency-domain multiplexing. A
single module, therefore, is fully functional as a miniature focal plane and
can be tested independently. Across the modules tested before deployment, the
detectors average a critical temperature of 478 mK, normal resistance R_N of
1.2 Ohm, unloaded saturation power of 22.5 pW, (detector-only) optical
efficiency of ~ 90%, and have electrothermal time constants < 1 ms in
transition.
10/2012;
-
E. M. George,
P. Ade,
K. A. Aird,
J. E. Austermann,
J. A. Beall,
D. Becker,
A. Bender,
B. A. Benson,
L. E. Bleem,
J. Britton, [......],
E. Shirokoff,
K. Story, C. Tucker,
K. Vanderlinde,
J. D. Vieira,
G. Wang,
R. Williamson,
V. Yefremenko,
K. W. Yoon,
E. Young
[show abstract]
[hide abstract]
ABSTRACT: In January 2012, the 10m South Pole Telescope (SPT) was equipped with a
polarization-sensitive camera, SPTpol, in order to measure the polarization
anisotropy of the cosmic microwave background (CMB). Measurements of the
polarization of the CMB at small angular scales (~several arcminutes) can
detect the gravitational lensing of the CMB by large scale structure and
constrain the sum of the neutrino masses. At large angular scales (~few
degrees) CMB measurements can constrain the energy scale of Inflation. SPTpol
is a two-color mm-wave camera that consists of 180 polarimeters at 90 GHz and
588 polarimeters at 150 GHz, with each polarimeter consisting of a dual
transition edge sensor (TES) bolometers. The full complement of 150 GHz
detectors consists of 7 arrays of 84 ortho-mode transducers (OMTs) that are
stripline coupled to two TES detectors per OMT, developed by the TRUCE
collaboration and fabricated at NIST. Each 90 GHz pixel consists of two
antenna-coupled absorbers coupled to two TES detectors, developed with Argonne
National Labs. The 1536 total detectors are read out with digital
frequency-domain multiplexing (DfMUX). The SPTpol deployment represents the
first on-sky tests of both of these detector technologies, and is one of the
first deployed instruments using DfMUX readout technology. We present the
details of the design, commissioning, deployment, on-sky optical
characterization and detector performance of the complete SPTpol focal plane.
10/2012;
-
P ~G Martin,
A Roy,
S Bontemps,
M -A Miville-Deschênes,
P ~A ~R Ade,
J ~J Bock,
E ~L Chapin,
M ~J Devlin,
S ~R Dicker,
M Griffin, [......],
L Olmi,
G Patanchon,
M Rex,
D Scott,
C Semisch,
M ~D ~P Truch, C Tucker,
G ~S Tucker,
M ~P Viero,
D ~V Wiebe
[show abstract]
[hide abstract]
ABSTRACT: The submillimeter opacity of dust in the diffuse interstellar medium (ISM) in the Galactic plane has been quantified using a pixel-by-pixel correlation of images of continuum emission with a proxy for column density. We used multi-wavelength continuum data: three Balloon-borne Large Aperture Submillimeter Telescope bands at 250, 350, and 500 $mu$m and one IRAS band at 100 $mu$m. The proxy is the near-infrared color excess, E(J - K $_s$), obtained from the Two Micron All Sky Survey. Based on observations of stars, we show how well this color excess is correlated with the total hydrogen column density for regions of moderate extinction. The ratio of emission to column density, the emissivity, is then known from the correlations, as a function of frequency. The spectral distribution of this emissivity can be fit by a modified blackbody, whence the characteristic dust temperature T and the desired opacity $sigma$$_e$(1200) at 1200 GHz or 250 $mu$m can be obtained. We have analyzed 14 regions near the Galactic plane toward the Vela molecular cloud, mostly selected to avoid regions of high column density (N $_H$ gt 10$^22$ cm$^-2$) and small enough to ensure a uniform dust temperature. We find $sigma$$_e$(1200) is typically (2-4) times 10$^-25$ cm$^2$ H$^-1$ and thus about 2-4 times larger than the average value in the local high Galactic latitude diffuse atomic ISM. This is strong evidence for grain evolution. There is a range in total power per H nucleon absorbed (and re-radiated) by the dust, reflecting changes in the strength of the interstellar radiation field and/or the dust absorption opacity. These changes in emission opacity and power affect the equilibrium T, which is typically 15 K, colder than at high latitudes. Our analysis extends, to higher opacity and lower temperature, the trend of increasing $sigma$$_e$(1200) with decreasing T that was found at high latitudes. The recognition of changes in the emission opacity raises a cautionary flag because all column densities deduced from dust emission maps, and the masses of compact structures within them, depend inversely on the value adopted.
apj. 01/2012; 751:28.
-
B. Keating,
S. Moyerman,
D. Boettger,
J Edwards,
G. Fuller,
F. Matsuda,
N. Miller,
H. Paar,
G. Rebeiz,
I. Schanning, [......],
M. Hazumi,
T Matsumura,
H Morii,
A Shimizu,
T Tomaru,
P. Hyland,
M. Dobbs,
P. Ade,
W. Grainger, C. Tucker
[show abstract]
[hide abstract]
ABSTRACT: Observations of the temperature anisotropy of the Cosmic Microwave Background
(CMB) lend support to an inflationary origin of the universe, yet no direct
evidence verifying inflation exists. Many current experiments are focussing on
the CMB's polarization anisotropy, specifically its curl component (called
"B-mode" polarization), which remains undetected. The inflationary paradigm
predicts the existence of a primordial gravitational wave background that
imprints a unique B-mode signature on the CMB's polarization at large angular
scales. The CMB B-mode signal also encodes gravitational lensing information at
smaller angular scales, bearing the imprint of cosmological large scale
structures (LSS) which in turn may elucidate the properties of cosmological
neutrinos. The quest for detection of these signals; each of which is orders of
magnitude smaller than the CMB temperature anisotropy signal, has motivated the
development of background-limited detectors with precise control of systematic
effects. The POLARBEAR experiment is designed to perform a deep search for the
signature of gravitational waves from inflation and to characterize lensing of
the CMB by LSS. POLARBEAR is a 3.5 meter ground-based telescope with 3.8
arcminute angular resolution at 150 GHz. At the heart of the POLARBEAR receiver
is an array featuring 1274 antenna-coupled superconducting transition edge
sensor (TES) bolometers cooled to 0.25 Kelvin. POLARBEAR is designed to reach a
tensor-to-scalar ratio of 0.025 after two years of observation -- more than an
order of magnitude improvement over the current best results, which would test
physics at energies near the GUT scale. POLARBEAR had an engineering run in the
Inyo Mountains of Eastern California in 2010 and will begin observations in the
Atacama Desert in Chile in 2011.
10/2011;
-
D Schwan,
P A R Ade,
K Basu,
A N Bender,
F Bertoldi,
H-M Cho,
G Chon,
John Clarke,
M Dobbs,
D Ferrusca, [......],
C L Reichardt,
P L Richards,
R Schaaf,
P Schilke,
M W Sommer,
H Spieler, C Tucker,
A Weiss,
B Westbrook,
O Zahn
[show abstract]
[hide abstract]
ABSTRACT: The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the Sunyaev-Zel'dovich effect from the 12 m APEX telescope on the Atacama plateau in Chile. The receiver contains a focal plane of 280 superconducting transition-edge sensor (TES) bolometers instrumented with a frequency-domain multiplexed readout system. The bolometers are cooled to 280 mK via a three-stage helium sorption refrigerator and a mechanical pulse-tube cooler. Three warm mirrors, two 4 K lenses, and a horn array couple the TES bolometers to the telescope. APEX-SZ observes in a single frequency band at 150 GHz with 1' angular resolution and a 22' field-of-view, all well suited for cluster mapping. The APEX-SZ receiver has played a key role in the introduction of several new technologies including TES bolometers, the frequency-domain multiplexed readout, and the use of a pulse-tube cooler with bolometers. As a result of these new technologies, the instrument has a higher instantaneous sensitivity and covers a larger field-of-view than earlier generations of Sunyaev-Zel'dovich instruments. The TES bolometers have a median sensitivity of 890 μK(CMB)√s (NEy of 3.5 × 10(-4) √s). We have also demonstrated upgraded detectors with improved sensitivity of 530 μK(CMB)√s (NEy of 2.2 × 10(-4) √s). Since its commissioning in April 2007, APEX-SZ has been used to map 48 clusters. We describe the design of the receiver and its performance when installed on the APEX telescope.
The Review of scientific instruments 09/2011; 82(9):091301. · 1.52 Impact Factor
-
A. A. Fraisse,
P. A. R. Ade,
M. Amiri,
S. J. Benton,
J. J. Bock,
J. R. Bond,
J. A. Bonetti,
S. Bryan,
B. Burger,
H. C. Chiang, [......],
J. E. Ruhl,
M. C. Runyan,
M. A. Schenker,
J. A. Shariff,
J. D. Soler,
A. Trangsrud, C. Tucker,
R. S. Tucker,
A. D. Turner,
D. Wiebe
[show abstract]
[hide abstract]
ABSTRACT: We evaluate the ability of SPIDER, a balloon-borne polarimeter, to detect a
divergence-free polarization pattern ("B-modes") in the Cosmic Microwave
Background (CMB). In the inflationary scenario, the amplitude of this signal is
proportional to that of the primordial scalar perturbations through the
tensor-to-scalar ratio r. We show that the expected level of systematic error
in the SPIDER instrument is significantly below the amplitude of an interesting
cosmological signal with r=0.03. We present a scanning strategy that enables us
to minimize uncertainty in the reconstruction of the Stokes parameters used to
characterize the CMB, while accessing a relatively wide range of angular
scales. Evaluating the amplitude of the polarized Galactic emission in the
SPIDER field, we conclude that the polarized emission from interstellar dust is
as bright or brighter than the cosmological signal at all SPIDER frequencies
(90 GHz, 150 GHz, and 280 GHz), a situation similar to that found in the
"Southern Hole." We show that two ~20-day flights of the SPIDER instrument can
constrain the amplitude of the B-mode signal to r<0.03 (99% CL) even when
foreground contamination is taken into account. In the absence of foregrounds,
the same limit can be reached after one 20-day flight.
06/2011;
-
J. E. Gudmundsson,
P. A. R. Ade,
M. Amiri,
S. J. Benton,
R. Bihary,
J. J. Bock,
J. R. Bond,
J. A. Bonetti,
S. A. Bryan,
H C Chiang, [......],
C.D. Reintsema,
J. E. Ruhl,
M. C. Runyan,
M. A. Schenker,
J. A. Shariff,
J. D. Soler,
A. Trangsrud, C. Tucker,
R. S. Tucker,
A. D. Turner
[show abstract]
[hide abstract]
ABSTRACT: We describe the cryogenic system for SPIDER, a balloon-borne microwave
polarimeter that will map 8% of the sky with degree-scale angular resolution.
The system consists of a 1284 L liquid helium cryostat and a 16 L
capillary-filled superfluid helium tank, which provide base operating
temperatures of 4 K and 1.5 K, respectively. Closed-cycle helium-3 adsorption
refrigerators supply sub-Kelvin cooling power to multiple focal planes, which
are housed in monochromatic telescope inserts. The main helium tank is
suspended inside the vacuum vessel with thermally insulating fiberglass
flexures, and shielded from thermal radiation by a combination of two vapor
cooled shields and multi-layer insulation. This system allows for an extremely
low instrumental background and a hold time in excess of 25 days. The total
mass of the cryogenic system, including cryogens, is approximately 1000 kg.
This enables conventional long duration balloon flights. We will discuss the
design, thermal analysis, and qualification of the cryogenic system.
06/2011;
-
J. P. Filippini,
P. A. R. Ade,
M. Amiri,
S. J. Benton,
R. Bihary,
J. J. Bock,
J. R. Bond,
J. A. Bonetti,
S. A. Bryan,
B. Burger, [......],
C.D. Reintsema,
J. E. Ruhl,
M. C. Runyan,
M. A. Schenker,
J. A. Shariff,
J. D. Soler,
A. Trangsrud, C. Tucker,
R. S. Tucker,
A. D. Turner
[show abstract]
[hide abstract]
ABSTRACT: 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.
06/2011;
-
M. C. Runyan,
P. A. R. Ade,
M. Amiri,
S. Benton,
R. Bihary,
J. J. Bock,
J. R. Bond,
J. A. Bonetti,
S. A. Bryan,
H C Chiang, [......],
A. S. Rahlin,
C.D. Reintsema,
J. E. Ruhl,
M. A. Schenker,
J. Shariff,
J. D. Soler,
A. Trangsrud,
R. S. Tucker, C. Tucker,
A Turner
[show abstract]
[hide abstract]
ABSTRACT: Here we describe the design and performance of the Spider instrument. Spider
is a balloon-borne cosmic microwave background polarization imager that will
map part of the sky at 90, 145, and 280 GHz with sub-degree resolution and high
sensitivity. This paper discusses the general design principles of the
instrument inserts, mechanical structures, optics, focal plane architecture,
thermal architecture, and magnetic shielding of the TES sensors and SQUID
multiplexer. We also describe the optical, noise, and magnetic shielding
performance of the 145 GHz prototype instrument insert.
06/2011;
-
D. S. Swetz,
P. A. R. Ade,
M. Amiri,
J. W. Appel,
E. S. Battistelli,
B. Burger,
J. Chervenak,
M. J. Devlin,
S. R. Dicker,
W. B. Doriese, [......],
M. R. Nolta,
L. A. Page,
L. Parker,
S. T. Staggs,
O. Stryzak,
E. R. Switzer,
R. Thornton, C. Tucker,
E. Wollack,
and Y. Zhao
[show abstract]
[hide abstract]
ABSTRACT: The Atacama Cosmology Telescope was designed to measure small-scale anisotropies in the cosmic microwave background and detect galaxy clusters through the Sunyaev-Zel'dovich effect. The instrument is located on Cerro Toco in the Atacama Desert, at an altitude of 5190 m. A 6 m off-axis Gregorian telescope feeds a new type of cryogenic receiver, the Millimeter Bolometer Array Camera. The receiver features three 1000-element arrays of transition-edge sensor bolometers for observations at 148 GHz, 218 GHz, and 277 GHz. Each detector array is fed by free space millimeter-wave optics. Each frequency band has a field of view of approximately 22' × 26'. The telescope was commissioned in 2007 and has completed its third year of operations. We discuss the major components of the telescope, camera, and related systems, and summarize the instrument performance.
The Astrophysical Journal Supplement Series 05/2011; 194(2):41. · 13.46 Impact Factor
-
A. Monfardini,
A. Benoit,
A. Bideaud,
L. Swenson,
A. Cruciani,
P. Camus,
C. Hoffmann,
F. X. Désert,
S. Doyle,
P. Ade, [......],
A. Endo,
A. Baryshev,
J. J. A. Baselmans,
L. Ferrari,
S. J. C Yates,
O. Bourrion,
J. Macias-Perez,
C. Vescovi,
M. Calvo,
and C. Giordano
[show abstract]
[hide abstract]
ABSTRACT: The Néel IRAM KIDs Array (NIKA) is a fully integrated measurement system based on kinetic inductance detectors (KIDs) currently being developed for millimeter wave astronomy. The instrument includes dual-band optics allowing simultaneous imaging at 150 GHz and 220 GHz. The imaging sensors consist of two spatially separated arrays of KIDs. The first array, mounted on the 150 GHz branch, is composed of 144 lumped-element KIDs. The second array (220 GHz) consists of 256 antenna-coupled KIDs. Each of the arrays is sensitive to a single polarization; the band splitting is achieved by using a grid polarizer. The optics and sensors are mounted in a custom dilution cryostat, with an operating temperature of ~70 mK. Electronic readout is realized using frequency multiplexing and a transmission line geometry consisting of a coaxial cable connected in series with the sensor array and a low-noise 4 K amplifier. The dual-band NIKA was successfully tested in 2010 October at the Institute for Millimetric Radio Astronomy (IRAM) 30 m telescope at Pico Veleta, Spain, performing in-line with laboratory predictions. An optical NEP was then calculated to be around 2 × 10–16 W Hz–1/2 (at 1 Hz) while under a background loading of approximately 4 pW pixel–1. This improvement in comparison with a preliminary run (2009) verifies that NIKA is approaching the target sensitivity for photon-noise limited ground-based detectors. Taking advantage of the larger arrays and increased sensitivity, a number of scientifically relevant faint and extended objects were then imaged including the Galactic Center SgrB2 (FIR1), the radio galaxy Cygnus A, and the NGC1068 Seyfert galaxy. These targets were all observed simultaneously in the 150 GHz and 220 GHz atmospheric windows.
The Astrophysical Journal Supplement Series 05/2011; 194(2):24. · 13.46 Impact Factor
-
A. Monfardini,
A. Benoit,
A. Bideaud,
L. J. Swenson,
M. Roesch,
F. X. Desert,
S. Doyle,
A. Endo,
A. Cruciani,
P. Ade, [......],
L Ferrari,
C. Giordano,
C. Hoffmann,
S. Leclercq,
J. F. Macias-Perez,
P. Mauskopf,
K. F. Schuster, C. Tucker,
C. Vescovi,
S. J. C. Yates
[show abstract]
[hide abstract]
ABSTRACT: Context. The Neel IRAM KIDs Array (NIKA) is a fully-integrated measurement
system based on kinetic inductance detectors (KIDs) currently being developed
for millimeter wave astronomy. In a first technical run, NIKA was successfully
tested in 2009 at the Institute for Millimetric Radio Astronomy (IRAM) 30-meter
telescope at Pico Veleta, Spain. This prototype consisted of a 27-42 pixel
camera imaging at 150 GHz. Subsequently, an improved system has been developed
and tested in October 2010 at the Pico Veleta telescope. The instrument
upgrades included dual-band optics allowing simultaneous imaging at 150 GHz and
220 GHz, faster sampling electronics enabling synchronous measurement of up to
112 pixels per measurement band, improved single-pixel sensitivity, and the
fabrication of a sky simulator to replicate conditions present at the
telescope. Results. The new dual-band NIKA was successfully tested in October
2010, performing in-line with sky simulator predictions. Initially the sources
targeted during the 2009 run were re-imaged, verifying the improved system
performance. An optical NEP was then calculated to be around 2 \dot 10-16
W/Hz1/2. This improvement in comparison with the 2009 run verifies that NIKA is
approaching the target sensitivity for photon-noise limited ground-based
detectors. Taking advantage of the larger arrays and increased sensitivity, a
number of scientifically-relevant faint and extended objects were then imaged
including the Galactic Center SgrB2(FIR1), the radio galaxy Cygnus A and the
NGC1068 Seyfert galaxy. These targets were all observed simultaneously in the
150 GHz and 220 GHz atmospheric windows.
02/2011;
-
D. T. O'Dea,
P. A. R. Ade,
M. Amiri,
S. J. Benton,
J. J. Bock,
J. R. Bond,
J. A. Bonetti,
S. Bryan,
B. Burger,
H C Chiang, [......],
J. E. Ruhl,
M. C. Runyan,
M. A. Schenker,
J. A. Shariff,
J. D. Soler,
A. Trangsrud, C. Tucker,
R. S. Tucker,
A. D. Turner,
D. Wiebe
[show abstract]
[hide abstract]
ABSTRACT: Spider is a balloon-borne instrument designed to map the polarization of the
cosmic microwave background (CMB) with degree-scale resolution over a large
fraction of the sky. Spider's main goal is to measure the amplitude of
primordial gravitational waves through their imprint on the polarization of the
CMB if the tensor-to-scalar ratio, r, is greater than 0.03. To achieve this
goal, instrumental systematic errors must be controlled with unprecedented
accuracy. Here, we build on previous work to use simulations of Spider
observations to examine the impact of several systematic effects that have been
characterized through testing and modeling of various instrument components. In
particular, we investigate the impact of the non-ideal spectral response of the
half-wave plates, coupling between focal plane components and the Earth's
magnetic field, and beam mismatches and asymmetries. We also present a model of
diffuse polarized foreground emission based on a three-dimensional model of the
Galactic magnetic field and dust, and study the interaction of this foreground
emission with our observation strategy and instrumental effects. We find that
the expected level of foreground and systematic contamination is sufficiently
low for Spider to achieve its science goals.
02/2011;
-
A. D. Hincks,
V. Acquaviva,
P. A. R. Ade,
P. Aguirre,
M. Amiri,
J. W. Appel,
L. F. Barrientos,
E. S. Battistelli,
J. R. Bond,
B. Brown, [......],
D. S. Swetz,
E. R. Switzer,
R. Thornton,
H. Trac, C. Tucker,
L. Verde,
R. Warne,
G. Wilson,
E. Wollack,
and Y. Zhao
[show abstract]
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ABSTRACT: The Atacama Cosmology Telescope (ACT) is currently observing the cosmic microwave background with arcminute resolution at 148 GHz, 218 GHz, and 277 GHz. In this paper, we present ACT's first results. Data have been analyzed using a maximum-likelihood map-making method which uses B-splines to model and remove the atmospheric signal. It has been used to make high-precision beam maps from which we determine the experiment's window functions. This beam information directly impacts all subsequent analyses of the data. We also used the method to map a sample of galaxy clusters via the Sunyaev-Zel'dovich (SZ) effect and show five clusters previously detected with X-ray or SZ observations. We provide integrated Compton-y measurements for each cluster. Of particular interest is our detection of the z = 0.44 component of A3128 and our current non-detection of the low-redshift part, providing strong evidence that the further cluster is more massive as suggested by X-ray measurements. This is a compelling example of the redshift-independent mass selection of the SZ effect.
The Astrophysical Journal Supplement Series 12/2010; 191(2):423. · 13.46 Impact Factor
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The Polarbear Collaboration,
J. Errard,
P. A. R. Ade,
A. Anthony,
K. Arnold,
F. Aubin,
D. Boettger,
J. Borrill,
C. Cantalupo,
M. A. Dobbs, [......],
H. Spieler,
B. Steinbach,
R. Stompor,
A Suzuki,
T Tomaru,
H T Tran, C. Tucker,
E. Quealy,
P. L. Richards,
O. Zahn
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ABSTRACT: We describe the Cosmic Microwave Background (CMB) polarization experiment
called Polarbear. This experiment will use the dedicated Huan Tran Telescope
equipped with a powerful 1,200-bolometer array receiver to map the CMB
polarization with unprecedented accuracy. We summarize the experiment, its
goals, and current status.
11/2010;
