The Simons Observatory 220 and 280 GHz Focal-Plane Module: Design and Initial Characterization
Erin Healy, Daniel Dutcher, Zachary Atkins, Jason Austermann, Steve K. Choi, Cody J. Duell, Shannon Duff, Nicholas Galitzki, Zachary B. Huber, Johannes Hubmayr,… 展开作者
Erin Healy, Daniel Dutcher, Zachary Atkins, Jason Austermann, Steve K. Choi, Cody J. Duell, Shannon Duff, Nicholas Galitzki, Zachary B. Huber, Johannes Hubmayr, Bradley R. Johnson, Heather McCarrick, Michael D. Niemack, Rita Sonka, Suzanne T. Staggs, Eve Vavagiakis, Yuhan Wang, Zhilei Xu, Kaiwen Zheng
The Simons Observatory (SO) will detect and map the temperature and polarization of the millimeter-wavelength sky from Cerro Toco, Chile across a range of angular scales, providing rich data sets for cosmological and astrophysical analysis. The SO focal planes will be tiled with compact hexagonal packages, called Universal Focal-plane Modules (UFMs), in which the transition-edge sensor (TES) detectors are coupled to 100 mK microwave-multiplexing electronics. Three different types of dichroic TES detector arrays with bands centered at 30/40, 90/150, and 220/280 GHz will be implemented across the 49 planned UFMs. The 90/150GHz and 220/280 GHz arrays each contain 1,764 TESes, which are read out with two 910x multiplexer circuits. The modules contain a series of densely routed silicon chips, which are packaged together in a controlled electromagnetic environment with robust heat-sinking to 100 mK. Following an overview of the module design, we report on early results from the first 220/280GHz UFM, including detector yield, as well as readout and detector noise levels.
The Simons Observatory (SO) is a suite of telescopes located in the Atacama Desert in Chile that will make sensitive measurements of the cosmic microwave background. There are a host of cosmological and astrophysical questions that SO is forecasted to address. The universal focal-plane modules (UFMs) populate the four SO telescope receiver focal planes. There are three varieties of UFMs, each of which contains transition-edge-sensor bolometers observing in two spectral bands between 30 and 290~GHz. We describe the novel mid-frequency UFMs, which target two of the six spectral bands at 90 and 1…
The Simons Observatory is a ground-based cosmic microwave background survey experiment that consists of three 0.5 m small-aperture telescopes and one 6 m large-aperture telescope, sited at an elevation of 5200 m in the Atacama Desert in Chile. SO will deploy 60,000 transition-edge sensor (TES) bolometers in 49 separate focal-plane modules across a suite of four telescopes covering 30/40 GHz low frequency (LF), 90/150 GHz mid frequency (MF), and 220/280 GHz ultra-high frequency (UHF). Each MF and UHF focal-plane module packages 1720 optical detectors spreading across 12 detector bias lines that…
The Simons Observatory (SO) is a ground based Cosmic Microwave Background experiment that will be deployed to the Atacama Desert in Chile. SO will field over 60,000 transition edge sensor (TES) bolometers that will observe in six spectral bands between 27 GHz and 280 GHz with the goal of revealing new information about the origin and evolution of the universe. SO detectors are grouped based on their observing frequency and packaged into Universal Focal Plane Modules, each containing up to 1720 detectors which are read out using microwave SQUID multiplexing and the SLAC Microresonator Radio Fre…
High quality, repeatable point-spread functions are important for science cases like direct exoplanet imaging, high-precision astrometry, and high-resolution spectroscopy of exoplanets. For such demanding applications, the initial on-sky point-spread function delivered by the adaptive optics system can require further optimization to correct unsensed static aberrations and calibration biases. We investigated using the Fast and Furious focal-plane wavefront sensing algorithm as a potential solution. This algorithm uses a simple model of the optical system and focal plane information to measure …
A common optical design for a coma-corrected, 6-meter aperture, crossed-Dragone telescope has been adopted for the CCAT-prime telescope of CCAT Observatory, Inc., and for the Large Aperture Telescope of the Simons Observatory. Both are to be built in the high altitude Atacama Desert in Chile for submillimeter and millimeter wavelength observations, respectively. The design delivers a high throughput, relatively flat focal plane, with a field of view 7.8 degrees in diameter for 3 mm wavelengths, and the ability to illuminate >100k diffraction-limited beams for < 1 mm wavelengths. The optics con…
The Simons Observatory (SO) is a ground-based cosmic microwave background survey experiment that consists of three 0.5 m small-aperture telescopes and one 6 m large-aperture telescope, sited at an elevation of 5200 m in the Atacama Desert in Chile. SO will study the polarization and temperature anisotropies of the Cosmic Microwave Background (CMB). The observatory will require well-understood telescope pointing and scanning. Good antenna control will allow us to execute the scan strategy devised to optimize sensitivity to our scientific goals, calibrate the system with celestial targets, and m…
The Simons Observatory (SO) will measure the cosmic microwave background (CMB) in both temperature and polarization over a wide range of angular scales and frequencies from 27-270 GHz with unprecedented sensitivity. One technology for coupling light onto the $\sim$50 detector wafers that SO will field is spline-profiled feedhorns, which offer tunability between coupling efficiency and control of beam polarization leakage effects. We will present efforts to scale up feedhorn production for SO and their viability for future CMB experiments, including direct-machining metal feedhorn arrays and la…
The Simons Observatory: Studies of Phase Drift in RF Transmission Lines from the First Large-Scale Deployment of Microwave Frequency Multiplexing for Cosmology
Stanford University（斯坦福大学）；Kavli Institute for Particle Astrophysics & Cosmology, Stanford（斯坦福粒子天体物理与宇宙学卡弗里研究所）；SLAC National Accelerator Laboratory（SLAC国家加速器实验室）；Cornell University（康奈尔大学）；Wright Laboratory, Department of Physics, Yale University（耶鲁大学物理莱特实验室）
The Simons Observatory (SO) will be a cosmic microwave background (CMB) survey experiment with three small-aperture telescopes and one large-aperture telescope, which will observe from the Atacama Desert in Chile. In total, SO will field over 60,000 transition-edge sensor (TES) bolometers in six spectral bands centered between 27 and 280 GHz in order to achieve the sensitivity necessary to measure or constrain numerous cosmological quantities, as outlined in The Simons Observatory Collaboration et al. (2019). These telescopes require 33 highly transparent, large aperture, refracting optics. To…
The Simons Observatory: Studies of Detector Yield and Readout Noise From the First Large-Scale Deployment of Microwave Multiplexing at the Large Aperture Telescope
The Simons Observatory (SO) is a suite of instruments sensitive to temperature and polarization of the cosmic microwave background (CMB) to be located at Cerro Toco in the Atacama Desert in Chile. Five telescopes, one large aperture telescope and four small aperture telescopes, will host roughly 70,000 highly multiplexed transition edge sensor (TES) detectors operated at 100 mK. Each SO focal plane module (UFM) couples 1,764 TESes to microwave resonators in a microwave multiplexing (uMux) readout circuit. Before detector integration, the 100 mK uMux components are packaged into multiplexing mo…
The Simons Observatory will consist of a single large (6 m diameter) telescope and a number of smaller (0.5 m diameter) refracting telescopes designed to measure the polarization of the Cosmic Microwave Background to unprecedented accuracy. The large aperture telescope is the same design as the CCAT-prime telescope, a modified Crossed Dragone design with a field-of-view of over 7.8 degrees diameter at 90 GHz. This paper presents an overview of the cold reimaging optics for this telescope and what drove our choice of 350-400 mm diameter silicon lenses in a 2.4 m cryostat over other possibilitie…
The Simons Observatory is building both large (6 m) and small (0.5 m) aperture telescopes in the Atacama desert in Chile to observe the cosmic microwave background (CMB) radiation with unprecedented sensitivity. Simons Observatory telescopes in total will use over 60,000 transition edge sensor (TES) detectors spanning center frequencies between 27 and 285 GHz and operating near 100 mK. TES devices have been fabricated for the Simons Observatory by NIST, Berkeley, and HYPRES/SeeQC corporation. Iterations of these devices have been tested cryogenically in order to inform the fabrication of furth…
The Simons Observatory (SO) is a ground-based cosmic microwave background (CMB) survey experiment that consists of three 0.5 m small-aperture telescopes (SATs) and one 6 m large-aperture telescope (LAT), sited at an elevation of 5200 m in the Atacama Desert in Chile. In order to meet the sensitivity requirements set for next-generation CMB telescopes, the LAT will deploy 30,000 transition edge sensor (TES) detectors at 100 mK across 7 optics tubes (OT), all within the Large Aperture Telescope Receiver (LATR). Additionally, the LATR has the capability to expand to 62,000 TES across 13 OTs. The …
The Simons Observatory: Overview of the Cryogenic Half-wave Plate Polarization Modulators
University of California Riverside（加州大学河滨分校）；Princeton University（普林斯顿大学）；University of California San Diego（加州大学圣地亚哥分校）；The University of Tokyo（东京大学）；The Suwa University of Science（信州大学（原諏訪科學大學））；University of Texas at Austin（德克萨斯大学奥斯汀分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）
The Simons Observatory: On-sky performance of radio-transparent multi-layer insulation (RT-MLI) using Styroace-II Styrofoam
Princeton University（普林斯顿大学）；University of Texas at Austin（德克萨斯大学奥斯汀分校）；The University of Tokyo（东京大学）；University of California San Diego（加州大学圣地亚哥分校）；Argonne National Laboratory（阿贡国家实验室）；University of Chicago（芝加哥大学）；High Energy Accelerator Research Organization (KEK)（高能加速器研究机构（KEK））；University of Virginia（弗吉尼亚大学）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）
The Simons Observatory (SO) will perform ground-based observations of the cosmic microwave background (CMB) with several small and large aperture telescopes, each outfitted with thousands to tens of thousands of superconducting aluminum manganese (AlMn) transition-edge sensor bolometers (TESs). In-situ characterization of TES responsivities and effective time constants will be required multiple times each observing-day for calibrating time-streams during CMB map-making. Effective time constants are typically estimated in the field by briefly applying small amplitude square-waves on top of the …
The Simons Observatory (SO) will be a cosmic microwave background (CMB) survey experiment with three small-aperture telescopes and one large-aperture telescope, which will observe from the Atacama Desert in Chile. In total, SO will field over 60,000 transition-edge sensor (TES) bolometers in six spectral bands centered between 27 and 280 GHz in order to achieve the sensitivity necessary to measure or constrain numerous cosmological quantities, as outlined in The Simons Observatory Collaboration et al. (2019). The 6~m Large Aperture Telescope (LAT), which will target the smaller angular scales …
We present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These measurements demonstrate that radio holography of complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization of wave propagation before deployment. We used the measured amplitude and phase, at 4K, of the receiver near-field beam pattern to predict two key performance parameters: 1) the amount of scattered light that will spill past the telescope to 300K and 2) the beam pattern expected from the rece…
The Simons Observatory (SO) is an upcoming polarized cosmic microwave background (CMB) survey experiment with three small-aperture telescopes and one large-aperture telescope that will observe from the Atacama Desert in Chile. In total, SO will field over 60,000 transition-edge sensor (TES) bolometers in six spectral bands centered between 27 and 280 GHz to achieve the sensitivity necessary to measure or constrain numerous cosmological parameters, including the tensor-to-scalar ratio, effective number of relativistic species, and sum of the neutrino masses. The SO scientific goals require coor…
The Simons Observatory (SO) will make precision temperature and polarization measurements of the cosmic microwave background (CMB) over angular scales between 1 arcminute and tens of degrees using over 60,000 detectors and sampling frequencies between 27 and 270 GHz. SO will consist of a six-meter-aperture telescope coupled to over 30,000 detectors and an array of half-meter aperture refractive cameras, coupled to an additional 30,000+ detectors. The unique combination of large and small apertures in a single CMB observatory will allow us to sample a wide range of angular scales over a common …
We present geometrical and physical optics simulation results for the Simons Observatory Large Aperture Telescope. This work was developed as part of the general design process for the telescope; allowing us to evaluate the impact of various design choices on performance metrics and potential systematic effects. The primary goal of the simulations was to evaluate the final design of the reflectors and the cold optics which are now being built. We describe non-sequential ray tracing used to inform the design of the cold optics, including absorbers internal to each optics tube. We discuss ray tr…
The Simons Observatory (SO) will make precision temperature and polarization measurements of the cosmic microwave background (CMB) using a series of telescopes which will cover angular scales between one arcminute and tens of degrees and sample frequencies between 27 and 270 GHz. Here we present the current design of the large aperture telescope receiver (LATR), a 2.4 m diameter cryostat that will be mounted on the SO 6 m telescope and will be the largest CMB receiver to date. The cryostat size was chosen to take advantage of the large focal plane area having high Strehl ratios, which is inher…
The Simons Observatory (SO) is a set of cosmic microwave background instruments that will be deployed in the Atacama Desert in Chile. The key science goals include setting new constraints on cosmic inflation, measuring large scale structure with gravitational lensing, and constraining neutrino masses. Meeting these science goals with SO requires high sensitivity and improved calibration techniques. In this paper, we highlight a few of the most important instrument calibrations, including spectral response, gain stability, and polarization angle calibrations. We present their requirements for S…
The Simons Observatory (SO) will observe the cosmic microwave background (CMB) from Cerro Toco in the Atacama Desert of Chile. The observatory consists of three 0.5 m Small Aperture Telescopes (SATs) and one 6 m Large Aperture Telescope (LAT), covering six frequency bands centering around 30, 40, 90, 150, 230, and 280 GHz. The SO observations will transform the understanding of our universe by characterizing the properties of the early universe, measuring the number of relativistic species and the mass of neutrinos, improving our understanding of galaxy evolution, and constraining the properti…
The Simons Observatory: Development of a Pipeline to Detect Rapid Transients in Time-Ordered Data
The University of Melbourne（墨尔本大学）；The International School for Advanced Studies (SISSA)（国际高等研究院）；The National Institute for Nuclear Physics (INFN)（意大利国家核物理研究所）；The National Institute for Astrophysics (INAF)（意大利国家天体物理研究所）；The Institute for Fundamental Physics of the Universe (IFPU)（宇宙基础物理研究所）；University of Pennsylvania（宾夕法尼亚大学）；University of Milano-Bicocca（米兰比可卡大学）；Princeton University（普林斯顿大学）；University of Toronto（多伦多大学）；Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；Specola Vaticana (Vatican Observatory)（梵蒂冈天文台）
The Simons Observatory (SO) will make precision temperature and polarization measurements of the cosmic microwave background (CMB) using a series of telescopes which will cover angular scales between one arcminute and tens of degrees, contain over 60,000 detectors, and sample frequencies between 27 and 270 GHz. SO will consist of a six-meter-aperture telescope coupled to over 30,000 detectors along with an array of half-meter aperture refractive cameras, which together couple to an additional 30,000+ detectors. SO will measure fundamental cosmological parameters of our universe, find high reds…
We report on the upgraded One Degree Imager (ODI) at the WIYN 3.5 meter telescope at the Kitt Peak Observatory after the focal plane was expanded by an additional seventeen detectors in spring 2015. The now thirty Orthogonal Transfer Array CCD detectors provide a total field of view of 40' x 48' on the sky. The newly added detectors underwent a design revision to mitigate reduced charge transfer efficiency under low light conditions. We discuss the performance of the focal plane and challenges in the photometric calibration of the wide field of view, helped by the addition of telescope baffles…
The Simons Observatory (SO) is an upcoming experiment that will study temperature and polarization fluctuations in the cosmic microwave background (CMB) from the Atacama Desert in Chile. SO will field both a large aperture telescope (LAT) and an array of small aperture telescopes (SATs) that will observe in six bands with center frequencies spanning from 27 to 270~GHz. Key considerations during the SO design phase are vast, including the number of cameras per telescope, focal plane magnification and pixel density, in-band optical power and camera throughput, detector parameter tolerances, and …
The differential Optical Transfer Function (dOTF) is a focal plane wavefront sensing method that uses a diversity in the pupil plane to generate two different focal plane images. The difference of their Fourier transforms recovers the complex amplitude of the pupil down to the spatial scale of the diversity. We produce two simultaneous PSF images with diversity using a polarizing filter at the edge of the telescope pupil, and a polarization camera to simultaneously record the two images. Here we present the first on-sky demonstration of polarization dOTF at the 1.0m South African Astronomical …
The Simons Observatory: Detector Polarization Angle Calibration using Sparse Wire Grid with Initial Data Sets of the Small Aperture Telescope
Kyoto University（京都大学）；Okayama University（冈山大学）；Princeton University（普林斯顿大学）；University of California San Diego（加州大学圣迭戈分校）；KEK（高能加速器研究机构）；The University of Tokyo（东京大学）；University of Milano-Bicocca（米兰比可卡大学）
The Simons Observatory (SO) is a Cosmic Microwave Background (CMB) experiment to observe the microwave sky in six frequency bands from 30GHz to 290GHz. The Observatory -- at $\sim$5200m altitude -- comprises three Small Aperture Telescopes (SATs) and one Large Aperture Telescope (LAT) at the Atacama Desert, Chile. This research note describes the design and current status of the LAT along with its future timeline.
Near-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 micron accuracy. We apply this approach to the example…
The Simons Observatory (SO) is an upcoming cosmic microwave background (CMB) experiment located on Cerro Toco, Chile, that will map the microwave sky in temperature and polarization in six frequency bands spanning 27 to 285 GHz. SO will consist of one 6-meter Large Aperture Telescope (LAT) fielding $\sim$30,000 detectors and an array of three 0.42-meter Small Aperture Telescopes (SATs) fielding an additional 30,000 detectors. This synergy will allow for the extremely sensitive characterization of the CMB over angular scales ranging from an arcmin to tens of degrees, enabling a wide range of sc…
The Simons Observatory (SO) is a ground-based cosmic microwave background (CMB) survey experiment that consists of three 0.5 m small-aperture telescopes and one 6 m large-aperture telescope, sited at an elevation of 5200 m in the Atacama Desert in Chile. SO will utilize more than 60,000 transition edge sensors (TES) to observe CMB temperature and polarization in six frequency bands from 27-280 GHz. Common to both the small and large aperture telescope receivers (LATR) is the 300K-4K Universal Readout Harness (URH), which supports up to 600 DC bias lines and 24 radio frequency (RF) channels con…
The Simons Observatory: Rotation Performance of Cryogenic Half-Wave Plate Polarization Modulators
Princeton University（普林斯顿大学）；University of California, San Diego（加利福尼亚大学圣地亚哥分校）；The University of Tokyo（东京大学）；The Suwa University of Science（诹访科学大学）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS（宇宙物理与数学研究所（WPI））；University of Texas at Austin（德克萨斯大学奥斯汀分校）；Weinberg Institute for Theoretical Physics（温伯格理论物理研究所）；Texas Center for Cosmology and Astroparticle Physics（德克萨斯宇宙学与高能天体物理中心）
The ATHENA X-ray Observatory-IXO is a planned multinational orbiting X-ray observatory with a focal length of 11.5m. ATHENA aims to perform pointed observations in an energy range from 0.1 keV to 15 keV with high sensitivity. For high spatial and timing resolution imaging and spectroscopic observations the 640x640 pixel^2 large DePFET-technology based Wide field Imager (WFI) focal plane detector, providing a field of view of 18 arcsec will be the main detector. Based on the actual mechanics, thermal and shielding design we present estimates for the WFI cosmic ray induced background obtained by…
We present the design, fabrication, and measured performance of metamaterial Anti-Reflection Cuttings (ARCs) for large-format alumina filters operating over more than an octave of bandwidth to be deployed on the Simons Observatory (SO). The ARC consists of sub-wavelength features diced into the optic's surface using a custom dicing saw with near-micron accuracy. The designs achieve percent-level control over reflections at angles of incidence up to 20$^\circ$. The ARCs were demonstrated on four 42 cm diameter filters covering the 75-170 GHz band and a 50 mm diameter prototype covering the 200-…
The Simons Observatory (SO) is an upcoming polarization-sensitive Cosmic Microwave Background (CMB) experiment on the Cerro Toco Plateau (Chile) with large overlap with other optical and infrared surveys (e.g., DESI, LSST, HSC). To enable the readout of \bigO(10,000) detectors in each of the four telescopes of SO, we will employ the microwave SQUID multiplexing technology. With a targeted multiplexing factor of \bigO{(1,000)}, microwave SQUID multiplexing has never been deployed on the scale needed for SO. Here we present the design of the cryogenic coaxial cable and RF component chain that co…
The Simons Observatory: Frequency-resolved beam calibration for the SO SATs with POLOCALC
University of Milano-Bicocca（米兰比可卡大学）；Istituto Nazionale di Fisica Nucleare, INFN, Sezione Milano-Bicocca（意大利国家核物理研究所，INFN，米兰-比可卡分部）；University of Texas at Austin（德克萨斯大学奥斯汀分校）；Weinberg Institute for Theoretical Physics and Texas Center for Cosmology and Astroparticle Physics（魏因伯格理论物理研究所和德克萨斯宇宙学与天体粒子物理中心）；Princeton University（普林斯顿大学）
Controlling stray light at millimeter wavelengths requires special optical design and selection of absorptive materials that should be compatible with cryogenic operating environments. While a wide selection of absorptive materials exists, these typically exhibit high indices of refraction and reflect/scatter a significant fraction of light before absorption. For many lower index materials such as commercial microwave absorbers, their applications in cryogenic environments are challenging. In this paper, we present a new tool to control stray light: metamaterial microwave absorber tiles. These…
The Simons Observatory (SO) is a cosmic microwave background (CMB) experiment from the Atacama Desert in Chile comprising three small-aperture telescopes (SATs) and one large-aperture telescope (LAT). In total, SO will field over 60,000 transition-edge sensor (TES) bolometers in six spectral bands centered between 27 and 280 GHz in order to achieve the sensitivity necessary to measure or constrain numerous cosmological quantities. In this work, we focus on the SATs which are optimized to search for primordial gravitational waves that are detected as parity-odd polarization patterns called a B-…
We present the design and measured performance of a new carbon fiber strut design that is used in a cryogenically cooled truss for the Simons Observatory Small Aperture Telescope (SAT). The truss consists of two aluminum 6061 rings separated by 24 struts. Each strut consists of a central carbon fiber tube fitted with two aluminum end caps. We tested the performance of the strut and truss by (i) cryogenically cycling and destructively pull-testing strut samples, (ii) non-destructively pull-testing the final truss, and (iii) measuring the thermal conductivity of the carbon fiber tubes. We found …
