71 research outputs found
Cryogenic Optics and Detectors for Next-Generation Microwave Cosmology and Astrophysics Observatories
No full text264 pagesMillimeter and sub-millimeter observatories provide a unique and powerful window into the origins, content, and evolution of the universe. In our current era of precision cosmology, measurements of the cosmic microwave background (CMB) yield constraints on frontier physics such as dark energy, the sum of the neutrino masses, and models of inflation. Measurements of the CMB also reveal the astrophysics of galaxy clusters and can then be used to glean information about the early universe. The early universe can also be studied with millimeter-wave observations of redshifted spectral line emissions from early star-forming galaxies during the Epoch of Reionization (EoR). A relatively new method, called spectral line intensity mapping (LIM), can be used to tomographically map the EoR. LIM observations of the EoR will reveal properties of the reionization sources and how reionization impacted the evolution of the intergalactic medium (IGM) into the large-scale structure we see today. In order to improve CMB observations and enable new LIM measurements, microwave observatories require high-throughput cryogenic optics and interferometry, and ultra-sensitive superconducting detectors. This dissertation presents developments of these technologies for three projects: the Atacama Cosmology Telescope (ACT), the CCAT-prime Observatory, and the Simons Observatory (SO). We begin with a presentation of in-situ warm spillover beam measurements of the Advanced ACT receiver, which have been used to improve the optical designs of future telescopes. We then discuss the design, models, and fabrication development of metamaterial-based, silicon-substrate, Fabry-Perot interferometers for CCAT-prime's [CII] LIM instrument. We then describe the characterization of prototype superconducting transition edge sensors (TES) for Simons Observatory including, critical temperature, saturation power, time constant, and complex impedance measurements. The dissertation concludes with a brief discussion of the cosmology and astrophysics science goals that these technologies will enable when they are deployed on microwave telescopes in the coming years
Monolithic Kilopixel Silicon Microlens Arrays for Future Far-Infrared Observatories
No full textFuture far-infrared astrophysics observatories will require focal plane
arrays containing thousands of ultra-sensitive, superconducting detectors, each
of which needs to be optically coupled to the telescope. At longer wavelengths,
many approaches have been developed including feedhorn arrays and macroscopic
arrays of lenslets. However, with wavelengths as short as 25 microns, optical
coupling in the far-infrared remains challenging. In this paper, we present a
novel approach for fabricating far-infrared monolithic silicon microlens arrays
using grayscale lithography and deep reactive ion etching. The design,
fabrication, and characterization of the microlens arrays are discussed. We
compare the designed and fabricated lens profile, and calculate that the
fabricated lenses will achieve 84% encircled power for the designed detector,
which is only 3% less than the designed performance. We also present methods
developed for anti-reflection coating microlens arrays and for a
silicon-to-silicon die bonding process to hybridize microlens arrays with
detector arrays
Paul et virginie: paratextos e textos em traduções brasileiras nos séculos XX e XXI
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Estudos da Tradução, Florianópolis, 2014.A presente tese tem como objetivo principal uma proposta de retradução comentada do romance Paut et Virginie do escritor francês Bernardin de Saint-Pierre. Como objetivo secundário, propõe-se uma análise das traduções brasileiras deste romance de 1906 à 2008 no sistema literário brasileiro sob o aspecto da "Visualização das Traduções" bem como um estudo dos paratextos traduzidos e não traduzidos. Tanto para a análise tradutória quanto para a retradução, são estudados trechos representativos a partir da teoria de Antoine Berman (1995), Gerard Genette (2010), Lawrence Venuti (1995). A análise dos excertos de narrativa poética baseia-se principalmente na teoria de Jean-Yves Tadié (1994).Abstract : The present work aims at proposing a commented retranslation on the novel Paul et Virginie, by the French author Bernardin de Saint-Pierre. As a secondary objective, we propose an analysis of the Brazilian translations of this novel from 1906 to 2008 into the Brazilian literary system under the perspective of "View of Translations" and a study of the translated and not translated paratexts. For both the translational analysis and the retranslation we used representative excerpts from the theoretical principles of Antoine Berman (1995), Gerard Genette (2010), and Lawrence Venuti (1995). The analysis of the excerpts of the poetic narrative is based mainly on Jean-Yves Tadié's theory
Recommended from our members
Readout of two-kilopixel transition-edge sensor arrays for Advanced ACTPol
No full textAdvanced ACTPol is an instrument upgrade for the six-meter Atacama Cosmology Telescope (ACT) designed to measure the cosmic microwave background (CMB) temperature and polarization with arcminute-scale angular resolution. To achieve its science goals, Advanced ACTPol utilizes a larger readout multiplexing factor than any previous CMB experiment to measure detector arrays with approximately two thousand transition-edge sensor (TES) bolometers in each 150 mm detector wafer. We present the implementation and testing of the Advanced ACTPol time-division multiplexing readout architecture with a 64-row multiplexing factor. This includes testing of individual multichroic detector pixels and superconducting quantum interference device (SQUID) multiplexing chips as well as testing and optimizing of the integrated readout electronics. In particular, we describe the new automated multiplexing SQUID tuning procedure developed to select and optimize the thousands of SQUID parameters required to readout each Advanced ACTPol array. The multichroic detector pixels in each array use separate channels for each polarization and each of the two frequencies, such that four TESes must be read out per pixel. Challenges addressed include doubling the number of detectors per multiplexed readout channel compared to ACTPol and optimizing the Nyquist inductance to minimize detector and SQUID noise aliasing
Highly Uniform 150 mm Diameter Multichroic Polarimeter Array Deployed for CMB Detection
No full textThe Advanced Atacama Cosmology Telescope Polarimeter is an upgraded receiver for the Atacama Cosmology Telescope, which has begun making measurements of the small angular scale polarization anisotropies in the Cosmic Microwave Background using the first of four new multichroic superconducting detector arrays. Here, we review all details of the optimization and characterization of this first array, which features 2012 AlMn transition edge sensor bolometers operating at 150 and 230 GHz. We present critical temperatures, thermal conductivities,saturation powers, time constants, and sensitivities for the array. The results show high uniformity across the 150 mm wafer and good performance in the field
Metal-Mesh Linear Variable Filter for Far-Infrared Wavelengths
No full textFuture far-infrared (IR) observatories require compact and cost efficient optical linear variable bandpass filters (LVBFs) to define their instrument spectral bands. We have designed novel far-IR LVBFs that consist of metal-mesh bandpass filters comprised of a gold film with cross-slots of varying sizes along a silicon (Si) substrate with anti-reflection (AR) coatings. We present our work on the simulated and measured transmission of non-AR coated and AR coated LVBFs for bandpass peaks from wavelengths of 24 to 36 m with a resolving power () of R6 for non-AR coated LVBFs and R4 for AR coated LVBFs. We also present a method to decrease the effects of out-of-band high frequency transmission exhibited by metal-mesh filters by depositing a thin layer of hydrogenated amorphous silicon (a-Si:H) on the metal-mesh of the LVBF. We have fabricated and measured the LVBFs at room temperature and cryogenic temperatures (5 K). We measure a high peak transmission of 80-90 \% for the AR coated LVBF at 5 K and demonstrate that the a-Si:H LVBF is a promising method to address out-of-band high frequency transmission.8 pages, 10 figures, accepted to Applied Optic
Far sidelobes from baffles and telescope support structures in the Atacama Cosmology Telescope
No full textRecommended from our members
Simons Observatory HoloSim-ML : machine learning applied to the efficient analysis of radio holography measurements of complex optical systems
No full textNear-field radio holography is a common method for measuring and aligning mirror surfaces for millimeter and sub-millimeter telescopes. In instruments with more than a single mirror, degeneracies arise in the holography measurement, requiring multiple measurements and new fitting methods. We present HoloSim-ML, a Python code for beam simulation and analysis of radio holography data from complex optical systems. This code uses machine learning to efficiently determine the position of hundreds of mirror adjusters on multiple mirrors with few micrometer accuracy. We apply this approach to the example of the Simons Observatory 6 m telescope.</p
High-sensitivity Kinetic Inductance Detector Arrays for the Probe Far-Infrared Mission for Astrophysics
No full textFar-infrared (far-IR) astrophysics missions featuring actively cooled
telescopes will offer orders of magnitude observing speed improvement at
wavelengths where galaxies and forming planetary systems emit most of their
light. The PRobe far-Infrared Mission for Astrophysics (PRIMA), which is
currently under study, emphasizes low and moderate resolution spectroscopy
throughout the far-IR. Full utilization of PRIMA's cold telescope requires
far-IR detector arrays with per-pixel noise equivalent powers (NEPs) at or
below 1 x 10-19 W/rtHz. We are developing low-volume Aluminum kinetic
inductance detector (KID) arrays to reach these sensitivities. We will present
on the development of our long-wavelength (210 um) array approach, with a focus
on multitone measurements of our 1,008-pixel arrays. We measure an NEP below 1
x 10-19 W/rtHz for 73 percent of our pixels.Comment: 9 pages, 5 figures, 20th International Workshop on Low Temperature
Detectors, submitted to the Journal of Low Temperature Physic
- …
