SuperSpec is an ultra-compact spectrometer-on-a-chip for mm and submm wavelength astronomy. Its very small size, wide spectral bandwidth, and highly multiplexed detector readout will enable ...construction of powerful multi-object spectrometers for observations of galaxies at high redshift. SuperSpec is a filter bank with planar, lithographed, superconducting transmission line resonator filters and lumped-element kinetic inductance detectors made from Titanium Nitride. We have built an 81 detector prototype that operates in the 195–310 GHz band. The prototype has a wide-band metal feed horn with a transition to microstrip that feeds the filter bank. The prototype has demonstrated optical filter bank channels with a range of resolving powers from 300 to 700, measured fractional frequency noise of
10
-
17
Hz
-
1
at
1
Hz.
SuperSpec is a novel on-chip spectrometer we are developing for (sub)millimeter wavelength astronomy. Our approach utilizes a filterbank of moderate resolution (
R
∼
500
)
channels, coupled to lumped ...element kinetic inductance detectors (KIDs), all integrated onto a single silicon chip. The channels are half-wave resonators formed by lithographically depositing segments of superconducting transmission line, and the KIDs are titanium nitride resonators. Here we present optical measurements of a first generation prototype, operating in the 180–280 GHz frequency range. We have used a coherent source to measure the spectral profiles of 17 channels, which achieve linewidths corresponding to quality factors as high as
Q
filt
=
700
,
consistent with the designed values plus additional dissipation characterized by
Q
i
≈
1440
.
We have also used a Fourier Transform Spectrometer to characterize the spectral purity of all 72 channels on the chip, and measure typical out of band responses
∼
30
dB below the peak response.
ABSTRACT The Keck Array is a system of cosmic microwave background polarimeters, each similar to the Bicep2 experiment. In this paper we report results from the 2012 to 2013 observing seasons, during ...which the Keck Array consisted of five receivers all operating in the same (150 GHz) frequency band and observing field as Bicep2. We again find an excess of B-mode power over the lensed-ΛCDM expectation of >5 in the range 30 < < 150 and confirm that this is not due to systematics using jackknife tests and simulations based on detailed calibration measurements. In map difference and spectral difference tests these new data are shown to be consistent with Bicep2. Finally, we combine the maps from the two experiments to produce final Q and U maps which have a depth of 57 nK deg (3.4 K arcmin) over an effective area of 400 deg2 for an equivalent survey weight of 250,000 K−2. The final BB band powers have noise uncertainty a factor of 2.3 times better than the previous results, and a significance of detection of excess power of >6 .
ABSTRACT We have developed antenna-coupled transition-edge sensor bolometers for a wide range of cosmic microwave background (CMB) polarimetry experiments, including Bicep2, Keck Array, and the ...balloon borne Spider. These detectors have reached maturity and this paper reports on their design principles, overall performance, and key challenges associated with design and production. Our detector arrays repeatedly produce spectral bands with 20%-30% bandwidth at 95, 150, or 230 GHz. The integrated antenna arrays synthesize symmetric co-aligned beams with controlled side-lobe levels. Cross-polarized response on boresight is typically , consistent with cross-talk in our multiplexed readout system. End-to-end optical efficiencies in our cameras are routinely 35% or higher, with per detector sensitivities of NET ∼ 300 . Thanks to the scalability of this design, we have deployed 2560 detectors as 1280 matched pairs in Keck Array with a combined instantaneous sensitivity of , as measured directly from CMB maps in the 2013 season. Similar arrays have recently flown in the Spider instrument, and development of this technology is ongoing.
We show measurements of thermal kinetic inductance detectors (TKIDs) intended for millimeter-wave cosmology in the 200–300 GHz atmospheric window. The TKID is a type of bolometer which uses the ...kinetic inductance of a superconducting resonator to measure the temperature of the thermally isolated bolometer island. We measure bolometer thermal conductance, time constant, and noise equivalent power. We also measure the quality factor of our resonators as the bath temperature varies to show they are limited by effects consistent with coupling to two-level systems.
Bicep2. III. INSTRUMENTAL SYSTEMATICS Ade, P. A. R.; Aikin, R. W.; Barkats, D. ...
The Astrophysical journal,
12/2015, Letnik:
814, Številka:
2
Journal Article
Recenzirano
Odprti dostop
ABSTRACT In a companion paper, we have reported a >5 detection of degree scale B-mode polarization at 150 GHz by the Bicep2 experiment. Here we provide a detailed study of potential instrumental ...systematic contamination to that measurement. We focus extensively on spurious polarization that can potentially arise from beam imperfections. We present a heuristic classification of beam imperfections according to their symmetries and uniformities, and discuss how resulting contamination adds or cancels in maps that combine observations made at multiple orientations of the telescope about its boresight axis. We introduce a technique, which we call "deprojection," for filtering the leading order beam-induced contamination from time-ordered data, and show that it reduces power in Bicep2's actual and null-test BB spectra consistent with predictions using high signal-to-noise beam shape measurements. We detail the simulation pipeline that we use to directly simulate instrumental systematics and the calibration data used as input to that pipeline. Finally, we present the constraints on BB contamination from individual sources of potential systematics. We find that systematics contribute BB power that is a factor of ∼10× below Bicep2's three-year statistical uncertainty, and negligible compared to the observed BB signal. The contribution to the best-fit tensor/scalar ratio is at a level equivalent to r = (3-6) × 10−3.
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