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.
Void galaxies, residing within the deepest underdensities of the Cosmic Web, present an ideal population for the study of galaxy formation and evolution in an environment undisturbed by the complex ...processes modifying galaxies in clusters and groups, as well as provide an observational test for theories of cosmological structure formation. We have completed a pilot survey for the H I imaging aspects of a new Void Galaxy Survey (VGS), imaging 15 void galaxies in H I in local (d < 100 Mpc) voids. H I masses range from 3.5 X 108 to 3.8 X 109 M , with one nondetection with an upper limit of 2.1 X 108 M . Our galaxies were selected using a structural and geometric technique to produce a sample that is purely environmentally selected and uniformly represents the void galaxy population. In addition, we use a powerful new backend of the Westerbork Synthesis Radio Telescope that allows us to probe a large volume around each targeted galaxy, simultaneously providing an environmentally constrained sample of fore- and background control samples of galaxies while still resolving individual galaxy kinematics and detecting faint companions in H I. This small sample makes up a surprisingly interesting collection of perturbed and interacting galaxies, all with small stellar disks. Four galaxies have significantly perturbed H I disks, five have previously unidentified companions at distances ranging from 50 to 200 kpc, two are in interacting systems, and one was found to have a polar H I disk. Our initial findings suggest void galaxies are a gas-rich, dynamic population which present evidence of ongoing gas accretion, major and minor interactions, and filamentary alignment despite the surrounding underdense environment.
BCR-ABL fusion proteins show increased signaling through their ABL tyrosine kinase domain, which can be blocked by specific inhibitors, thereby providing effective treatment. This makes detection of ...BCR-ABL aberrations of utmost importance for diagnosis, classification and treatment of leukemia patients. BCR-ABL aberrations are currently detected by karyotyping, fluorescence in situ hybridization (FISH) or PCR techniques, which are time consuming and require specialized facilities. We developed a simple flow cytometric immunobead assay for detection of BCR-ABL fusion proteins in cell lysates, using a bead-bound anti-BCR catching antibody and a fluorochrome-conjugated anti-ABL detection antibody. We noticed protein stability problems in lysates caused by proteases from mature myeloid cells. This problem could largely be solved by adding protease inhibitors in several steps of the immunobead assay. Testing of 145 patient samples showed fully concordant results between the BCR-ABL immunobead assay and reverse transcriptase PCR of fusion gene transcripts. Dilution experiments with BCR-ABL positive cell lines revealed sensitivities of at least 1%. We conclude that the BCR-ABL immunobead assay detects all types of BCR-ABL proteins in leukemic cells with high specificity and sensitivity. The assay does not need specialized laboratory facilities other than a flow cytometer, provides results within approximately 4 h, and can be run in parallel to routine immunophenotyping.
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 .
We present the strongest constraints to date on anisotropies of cosmic microwave background (CMB) polarization rotation derived from 150 GHz data taken by the BICEP2 & Keck Array CMB experiments up ...to and including the 2014 observing season (BK14). The definition of the polarization angle in BK14 maps has gone through self-calibration in which the overall angle is adjusted to minimize the observed TB and EB power spectra. After this procedure, the QU maps lose sensitivity to a uniform polarization rotation but are still sensitive to anisotropies of polarization rotation. This analysis places constraints on the anisotropies of polarization rotation, which could be generated by CMB photons interacting with axionlike pseudoscalar fields or Faraday rotation induced by primordial magnetic fields. The sensitivity of BK14 maps (∼3 μK−arc min) makes it possible to reconstruct anisotropies of the polarization rotation angle and measure their angular power spectrum much more precisely than previous attempts. Our data are found to be consistent with no polarization rotation anisotropies, improving the upper bound on the amplitude of the rotation angle spectrum by roughly an order of magnitude compared to the previous best constraints. Our results lead to an order of magnitude better constraint on the coupling constant of the Chern-Simons electromagnetic term gaγ≤7.2×10−2/HI (95% confidence) than the constraint derived from the B-mode spectrum, where HI is the inflationary Hubble scale. This constraint leads to a limit on the decay constant of 10−6≲fa/Mpl at mass range of 10−33≤ma≤10−28 eV for r=0.01, assuming gaγ∼α/(2πfa) with α denoting the fine structure constant. The upper bound on the amplitude of the primordial magnetic fields is 30 nG (95% confidence) from the polarization rotation anisotropies.
The BICEP2 CMB polarization experiment
Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE,
01/2010
Conference Proceeding
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