The cosmic microwave background: observing directly the early universe

The Cosmic Microwave Background (CMB) is a relict of the early universe. Its perfect 2.725K blackbody spectrum demonstrates that the universe underwent a hot, ionized early phase; its anisotropy (about 80 \mu K rms) provides strong evidence for the presence of photon-matter oscillations in the primeval plasma, shaping the initial phase of the formation of structures; its polarization state (about 3 \mu K rms), and in particular its rotational component (less than 0.1 \mu K rms) might allow to study the inflation process in the very early universe, and the physics of extremely high energies, impossible to reach with accelerators. The CMB is observed by means of microwave and mm-wave telescopes, and its measurements drove the development of ultra-sensitive bolometric detectors, sophisticated modulators, and advanced cryogenic and space technologies. Here we focus on the new frontiers of CMB research: the precision measurements of its linear polarization state, at large and intermediate angular scales, and the measurement of the inverse-Compton effect of CMB photons crossing clusters of Galaxies. In this framework, we will describe the formidable experimental challenges faced by ground-based, near-space and space experiments, using large arrays of detectors. We will show that sensitivity and mapping speed improvement obtained with these arrays must be accompanied by a corresponding reduction of systematic effects (especially for CMB polarimeters), and by improved knowledge of foreground emission, to fully exploit the huge scientific potential of these missions.Comment: In press. Plenary talk. Copyright 2012 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibite

Electronics and data acquisition demonstrator for a kinetic inductance camera

A prototype of digital frequency multiplexing electronics allowing the real time monitoring of kinetic inductance detector (KIDs) arrays for mm-wave astronomy has been developed. It requires only 2 coaxial cables for instrumenting a large array. For that, an excitation comb of frequencies is generated and fed through the detector. The direct frequency synthesis and the data acquisition relies heavily on a large FPGA using parallelized and pipelined processing. The prototype can instrument 128 resonators (pixels) over a bandwidth of 125 MHz. This paper describes the technical solution chosen, the algorithm used and the results obtained

Design and performance of kinetic inductance detectors for cosmic microwave background polarimetry

This thesis presents the development of kinetic inductance detectors (KIDs) for cosmic microwave background (CMB) polarimetry. Increasingly precise measurements of the CMB have led to much of our understanding of the observable universe; future measurements of the CMB will require the development of new detectors as progressively fainter signals are targeted. In particular, a measurement of the primordial B-mode polarization signal, which would offer strong evidence of inflation, will require at least a 50 times increase in detector count. KIDs are an attractive detector option for next-generation CMB experiments due to their low-noise and high-multiplexing factor. In this thesis, I present KIDs optimized for ground-based CMB observations, which are sensitive to a 150 GHz spectral band where the CMB spectrum peaks. This research demonstrates the first systematic studies of lumped-element KIDs (LEKIDs) optimized for CMB surveys and shows the readiness of the detectors for on-sky observations. First, I present the design and performance of horn-coupled LEKIDs, which are sensitive to a single polarization. I show that KIDs can meet the stringent noise and sensitivity requirements necessary for a competitive CMB detector. Second, I present a novel method for reducing crosstalk between LEKIDs, which is important for controlling instrument systematics. Third, I present the design and performance of dual-polarization LEKIDs, which are sensitive to orthogonal polarizations within a single spectral band and double the number of detectors per array, increasing the sensitivity. Finally, I present the initial analysis of millimeter-wave observations of a nearby galaxy cluster, Abell 2443, taken with the LEKID-based NIKA2 instrument on the IRAM 30 m telescope. This is part of ongoing research to make high-resolution measurements of the Sunyaev–Zel'dovich effect, seen as a distortion in the CMB spectrum

Large-format, transmission-line-coupled kinetic inductance detector arrays for HEP at millimeter wavelengths

The kinetic inductance detector (KID) is a versatile and scalable detector technology with a wide range of applications. These superconducting detectors offer significant advantages: simple and robust fabrication, intrinsic multiplexing that will allow thousands of detectors to be read out with a single microwave line, and simple and low cost room temperature electronics. These strengths make KIDs especially attractive for HEP science via mm-wave cosmological studies. Examples of these potential cosmological observations include studying cosmic acceleration (Dark Energy) through measurements of the kinetic Sunyaev-Zeldovich effect, precision cosmology through ultra-deep measurements of small-scale CMB anisotropy, and mm-wave spectroscopy to map out the distribution of cosmological structure at the largest scales and highest redshifts. The principal technical challenge for these kinds of projects is the successful deployment of large-scale high-density focal planes -- a need that can be addressed by KID technology. In this paper, we present an overview of microstrip-coupled KIDs for use in mm-wave observations and outline the research and development needed to advance this class of technology and enable these upcoming large-scale experiments

The CCAT-Prime Submillimeter Observatory

The Cerro Chajnantor Atacama Telescope-prime (CCAT-prime) is a new 6-m, off-axis, low-emissivity, large field-of-view submillimeter telescope scheduled for first light in the last quarter of 2021. In summary, (a) CCAT-prime uniquely combines a large field-of-view (up to 8-deg), low emissivity telescope (< 2%) and excellent atmospheric transmission (5600-m site) to achieve unprecedented survey capability in the submillimeter. (b) Over five years, CCAT-prime first generation science will address the physics of star formation, galaxy evolution, and galaxy cluster formation; probe the re-ionization of the Universe; improve constraints on new particle species; and provide for improved removal of dust foregrounds to aid the search for primordial gravitational waves. (c) The Observatory is being built with non-federal funds (~ \$40M in private and international investments). Public funding is needed for instrumentation (~ \$8M) and operations (\$1-2M/yr). In return, the community will be able to participate in survey planning and gain access to curated data sets. (d) For second generation science, CCAT-prime will be uniquely positioned to contribute high-frequency capabilities to the next generation of CMB surveys in partnership with the CMB-S4 and/or the Simons Observatory projects or revolutionize wide-field, sub-millimetter line intensity mapping surveys.Comment: Astro2020 APC White Pape

A microwave kinetic inductance camera for sub/millimeter astrophysics

The MKID Camera is a millimeter/submillimeter instrument being built for astronomical observations from the Caltech Submillimeter Observatory. It utilizes microwave kinetic inductance detectors, which are rapidly achieving near-BLIP sensitivity for ground-based observations, and a software-defined radio readout technique for elegant multiplexing of a large number of detectors. The Camera will have 592 pixels distributed over 16 tiles in the focal plane, with four colors per pixel matched to the 750 μm, 850 μm, and 1.0 - 1.5 mm (split in two) atmospheric transmission windows. As a precursor to building the full-up camera and to enable ongoing detector testing, we have built a DemoCam comprised of a 16-pixel MKID array with which we have made preliminary astronomical observations. These observations demonstrate the viability of MKIDs for submillimeter astronomy, provide insight into systematic design issues that must be considered for MKID-based instruments, and they are the first astronomical observations with antenna-coupled superconducting detectors. In this paper, we describe the basic systems and specifications of the MKID Camera, we describe our DemoCam observations, and we comment on the status of submillimeter MKID sensitivities

Developments of Microwave Kinetic Inductance Detectors

In this thesis, I will cover the fabrication, testing, and analysis of microwave kinetic inductance detectors (MKIDs) for both THz and mm-wave spectroscopy. MKIDs are a detector technology that enables large numbers of highly-sensistive mm/submm detectors to be read out using a small number of readout lines, which enables large-format spectroscopy. They can be produced such that a small piece of silicon contains both the spectrometer and detector. The RAxDEx project produced prototype THz spectrometers with a novel, in-chip rectangular waveguide. THz spectroscopy with MKIDs will enable the coupling of large fields-of-view to multi-kilopixel detectors. These devices would drastically improve our ability to map the cooling gas around galactic fountains by using hyperfine cooling lines among other uses for far-infrared spectroscopy. I present prototype dark MKIDs for RaxDEx that match design and noise specifications. In addition, SPT-SLIM is a project to create a mm-wave spectrometer for line intensity mapping with the South Pole Telescope. Line intensity mapping is expected to dramatically increase our knowledge of large scale cosmological structure, particularly in regards to galaxies that are too dim to be detected directly. I will present both dark and optical measurements from SPT-SLIM devices from initial prototypes to the final design submodules. Finally, I will cover an initial analysis of how SPT-SLIM will use unresolved, high-redshift galaxies to constrain the CO power spectrum and the luminosity function