This PDF file contains the front matter associated with SPIE Proceedings Volume 9153, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

The New IRAM KID Array (NIKA) is a dual-band camera operating with frequency multiplexed arrays of Lumped Element Kinetic Inductance Detectors (LEKIDs) cooled to 100 mK. NIKA is designed to observe the intensity and polarisation of the sky at 1.25 and 2.14 mm from the IRAM 30 m telescope. We present the improvements on the control of systematic effects and astrophysical results made during the last observation campaigns between 2012 and 2014.

instrument’s twin focal planes, each with over 5000 superconducting Transition Edge Sensors (TES) that work simultaneously at 450 and 850 microns are producing excellent science results and in particular a unique series of JCMT legacy surveys. In this paper we give an update on the performance of the instrument over the past 2 years of science operations and present the results of a study into the noise properties of the TES arrays. We highlight changes that have been implemented to increase the efficiency and performance of SCUBA-2 and discus the potential for future enhancements.

The Multiwavelength Sub/millimeter Inductance Camera (MUSIC) is a four-band photometric imaging camera operating from the Caltech Submillimeter Observatory (CSO). MUSIC is designed to utilize 2304 microwave kinetic inductance detectors (MKIDs), with 576 MKIDs for each observing band centered on 150, 230, 290, and 350 GHz. MUSIC’s field of view (FOV) is 14′ square, and the point-spread functions (PSFs) in the four observing bands have 45′′, 31′′, 25′′, and 22′′ full-widths at half maximum (FWHM). The camera was installed in April 2012 with 25% of its nominal detector count in each band, and has subsequently completed three short sets of engineering observations and one longer duration set of early science observations. Recent results from on-sky characterization of the instrument during these observing runs are presented, including achieved map- based sensitivities from deep integrations, along with results from lab-based measurements made during the same period. In addition, recent upgrades to MUSIC, which are expected to significantly improve the sensitivity of the camera, are described.

ArTeMiS is a wide-field submillimeter camera operating at three wavelengths simultaneously (200, 350 and 450 μm). A preliminary version of the instrument equipped with the 350 μm focal plane, has been successfully installed and tested on APEX telescope in Chile during the 2013 and 2014 austral winters. This instrument is developed by CEA (Saclay and Grenoble, France), IAS (France) and University of Manchester (UK) in collaboration with ESO. We introduce the mechanical and optical design, as well as the cryogenics and electronics of the ArTéMiS camera. ArTeMiS detectors consist in Si:P:B bolometers arranged in 16×18 sub-arrays operating at 300 mK. These detectors are similar to the ones developed for the Herschel PACS photometer but they are adapted to the high optical load encountered at APEX site. Ultimately, ArTeMiS will contain 4 sub-arrays at 200 μm and 2×8 sub-arrays at 350 and 450 μm. We show preliminary lab measurements like the responsivity of the instrument to hot and cold loads illumination and NEP calculation. Details on the on-sky commissioning runs made in 2013 and 2014 at APEX are shown. We used planets (Mars, Saturn, Uranus) to determine the flat-field and to get the flux calibration. A pointing model was established in the first days of the runs. The average relative pointing accuracy is 3 arcsec. The beam at 350 μm has been estimated to be 8.5 arcsec, which is in good agreement with the beam of the 12 m APEX dish. Several observing modes have been tested, like “On- The-Fly” for beam-maps or large maps, spirals or raster of spirals for compact sources. With this preliminary version of ArTeMiS, we concluded that the mapping speed is already more than 5 times better than the previous 350 μm instrument at APEX. The median NEFD at 350 μm is 600 mJy.s1/2, with best values at 300 mJy.s^1/2. The complete instrument with 5760 pixels and optimized settings will be installed during the first half of 2015.

Large area spiderweb bolometers of 8 mm diameter and a mesh size of 250 μm are fabricated in order to couple with approximately the first 20 modes of a multimode EM cavity at about 140 GHz. The sensor is a Ti/Au/Ti 3 layer TES with Tc tuned in the 330-380 mK and 2 mK transition width. We describe the detector design and the fabrication process, early TES electro-thermal measurements. We also report optical coupling measurement and show the multimode coupling.

In this paper we give a detailed analysis of the expected sensitivity and operating conditions in the power detection mode of a hot-electron bolometer (HEB) made from a few μm² of monolayer graphene (MLG) flake which can be embedded into either a planar antenna or waveguide circuit via NbN (or NbTiN) superconducting contacts with critical temperature ~ 14 K. Recent data on the strength of the electron-phonon coupling are used in the present analysis and the contribution of the readout noise to the Noise Equivalent Power (NEP) is explicitly computed. The readout scheme utilizes Johnson Noise Thermometry (JNT) allowing for Frequency-Domain Multiplexing (FDM) using narrowband filter coupling of the HEBs. In general, the filter bandwidth and the summing amplifier noise have a significant effect on the overall system sensitivity. The analysis shows that the readout contribution can be reduced to that of the bolometer phonon noise if the detector device is operated at 0.05 K and the JNT signal is read at about 10 GHz where the Johnson noise emitted in equilibrium is substantially reduced. Beside the high sensitivity (NEP < 10^-20 W/Hz^1/2), this bolometer does not have any hard saturation limit and thus can be used for far-IR sky imaging with arbitrary contrast. By changing the operating temperature of the bolometer the sensitivity can be fine tuned to accommodate the background photon flux in a particular application. By using a broadband low-noise kinetic inductance parametric amplifier, ~100s of graphene HEBs can be read simultaneously without saturation of the system output.

Future sky surveys in the mm/sub-mm range, like the forthcoming balloon-borne missions LSPE, OLIMPO, SPIDER etc., will need detectors insensitive to cosmic rays (CRs) and with a NEP of the order of 10^-17 ¥ 10^-18 W/sqrt(Hz). The Cold-Electron Bolometers (CEBs) technology is promising, having the required proper- ties, since the absorber volume is extremely small and the electron system of the absorber is thermally insulated from the phonon system. We have developed an experimental setup to test the optical performance and the CRs insensitivity of CEBs, with the target of integrating them in the OLIMPO and LSPE focal planes.

We report on the status and development of polarization-sensitive detectors for millimeter-wave applications. The detectors are fabricated on single-crystal silicon, which functions as a low-loss dielectric substrate for the microwave circuitry as well as the supporting membrane for the Transition-Edge Sensor (TES) bolometers. The orthomode transducer (OMT) is realized as a symmetric structure and on-chip filters are employed to define the detection bandwidth. A hybridized integrated enclosure reduces the high-frequency THz mode set that can couple to the TES bolometers. An implementation of the detector architecture at Q-band achieves 90% efficiency in each polarization. The design is scalable in both frequency coverage, 30-300 GHz, and in number of detectors with uniform characteristics. Hence, the detectors are desirable for ground-based or space-borne instruments that require large arrays of efficient background-limited cryogenic detectors.

We have characterized the optical response of prototype detectors for SAFARI, the far-infrared imaging spectrometer for the SPICA satellite. SAFARI's three bolometer arrays will image a 2’×2’ field of view with spectral information over the wavelength range 34—210 μm. SAFARI requires extremely sensitive detectors (goal NEP ~ 0.2 aW/√Hz), with correspondingly low saturation powers (~5 fW), to take advantage of SPICA's cooled optics. We have constructed an ultra-low background optical test facility containing an internal cold black-body illuminator and have recently added an internal hot black-body source and a light-pipe for external illumination. We illustrate the performance of the test facility with results including spectral-response measurements. Based on an improved understanding of the optical throughput of the test facility we find an optical efficiency of 60% for prototype SAFARI detectors.

The Tomographic Ionized carbon Mapping Experiment (TIME) is a multi-phased experiment that will topographically map [CII] emission from the Epoch of Reionization. We are developing lithographed spectrometers that couple to TES bolometers in anticipation of the second generation instrument. Our design intentionally mirrors many features of the parallel SuperSpec project, inductively coupling power from a trunk-line microstrip onto half-wave resonators. The resonators couple to a rat-race hybrids that feeds TES bolometers. Our 25 channel prototype shows spectrally positioned lines roughly matching design with a receiver optical efficiency of 15-20%, a level that is dominated by loss in components outside the spectrometer.

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) is a suborbital mapping experiment designed to study the role magnetic fields play in star formation. BLASTPol has had two science flights from McMurdo Station, Antarctica in 2010 and 2012. These flights have produced thousands of polarization vectors at 250, 350 and 500 microns in several molecular cloud targets. We present the design, specifications, and progress towards the next-generation BLASTPol experiment (BLAST-TNG). BLAST-TNG will fly a 40% larger diameter primary mirror, with almost 8 times the number of polarization-sensitive detectors resulting in a factor of 16 increase in mapping speed. With a spatial resolution of 2200 and four times the field of view (340 arcmin2) of BLASTPol, BLAST-TNG will bridge the angular scales between Planck's all-sky maps with 50 resolution and ALMA's ultra-high resolution narrow (~ 2000) fields. The new receiver has a larger cryogenics volume, allowing for a 28 day hold time. BLAST-TNG employs three arrays of Microwave Kinetic Inductance Detectors (MKIDs) with 30% fractional bandwidth at 250, 350 and 500 microns. In this paper, we will present the new BLAST-TNG instrument and science objectives.

MUSTANG 2 is a 223 element focal plane that operates between 75 and 105 GHz on the 100 meter Green Bank Telescope. It shares many of the science goals of its predecessor, MUSTANG, but will have fifteen times the sensitivity and five times the field-of-view. Angular scales from 900 to 60 will be recovered with high fidelity providing a unique overlap between high resolution instruments such as ALMA and lower resolution single dish telescopes such as ACT or SPT. Individual TES bolometers are placed behind feedhorns spaced by 1.9λ f and are read out using a microwave SQUID multiplexing system.

We report on the laboratory testing of KAPPa, a 16-pixel proof-of-concept array to enable the creation THz imaging spectrometer with ~1000 pixels. Creating an array an order of magnitude larger than the existing state of the art of 64 pixels requires a simple and robust design as well as improvements to mixer selection, testing, and assembly. Our testing employs a single pixel test bench where a novel 2D array architecture is tested. The minimum size of the footprint is dictated by the diameter of the drilled feedhorn aperture. In the adjoining detector block, a 6mm × 6mm footprint houses the SIS mixer, LNA, matching and bias networks, and permanent magnet. We present an initial characterization of the single pixel prototype using a computer controlled test bench to determine Y-factors for a parameter space of LO power, LO frequency, IF bandwidth, magnet field strength, and SIS bias voltage. To reduce the need to replace poorly preforming pixels that are already mounted in a large format array, we show techniques to improve SIS mixer selection prior to mounting in the detector block. The 2D integrated 16-pixel array design has been evolved as we investigate the properties of the single pixel prototype. Carful design of the prototype has allowed for rapid translation of single pixel design improvements to be easily incorporated into the 16-pixel model.

We describe the Short Wavelength Camera (SWCam) for the CCAT observatory including the primary science drivers, the coupling of the science drivers to the instrument requirements, the resulting implementation of the design, and its performance expectations at first light. CCAT is a 25 m submillimeter telescope planned to operate at 5600 meters, near the summit of Cerro Chajnantor in the Atacama Desert in northern Chile. CCAT is designed to give a total wave front error of 12.5 μm rms, so that combined with its high and exceptionally dry site, the facility will provide unsurpassed point source sensitivity deep into the short submillimeter bands to wavelengths as short as the 200 μm telluric window. The SWCam system consists of 7 sub-cameras that address 4 different telluric windows: 4 subcameras at 350 μm, 1 at 450 μm, 1 at 850 μm, and 1 at 2 mm wavelength. Each sub-camera has a 6’ diameter field of view, so that the total instantaneous field of view for SWCam is equivalent to a 16’ diameter circle. Each focal plane is populated with near unit filling factor arrays of Lumped Element Kinetic Inductance Detectors (LEKIDs) with pixels scaled to subtend an solid angle of (λ/D)2 on the sky. The total pixel count is 57,160. We expect background limited performance at each wavelength, and to be able to map < 35(°)2 of sky to 5 σ on the confusion noise at each wavelength per year with this first light instrument. Our primary science goal is to resolve the Cosmic Far-IR Background (CIRB) in our four colors so that we may explore the star and galaxy formation history of the Universe extending to within 500 million years of the Big Bang. CCAT's large and high-accuracy aperture, its fast slewing speed, use of instruments with large format arrays, and being located at a superb site enables mapping speeds of up to three orders of magnitude larger than contemporary or near future facilities and makes it uniquely sensitive, especially in the short submm bands.

SuperSpec is a novel on-chip spectrometer we are developing for multi-object, moderate resolution (R = 100 − 500), large bandwidth (~1.65:1) submillimeter and millimeter survey spectroscopy of high-redshift galaxies. The spectrometer employs a filter bank architecture, and consists of a series of half-wave resonators formed by lithographically-patterned superconducting transmission lines. The signal power admitted by each resonator is detected by a lumped element titanium nitride (TiN) kinetic inductance detector (KID) operating at 100 – 200 MHz. We have tested a new prototype device that is more sensitive than previous devices, and easier to fabricate. We present a characterization of a representative R = 282 channel at f = 236 GHz, including measurements of the spectrometer detection efficiency, the detector responsivity over a large range of optical loading, and the full system optical efficiency. We outline future improvements to the current system that we expect will enable construction of a photon-noise-limited R = 100 filter bank, appropriate for a line intensity mapping experiment targeting the [CII] 158 μm transition during the Epoch of Reionization.

This paper summarizes the performance of all the 73 ALMA band 10 cartridges in terms of noise performance and/or optical efficiencies compared to the required ALMA specifications. In particular, the measured optical performance is compared with the results of novel statistical Monte Carlo analyses carried out before receiver production. Some of the technical difficulties encountered during production are briefly described. Finally, some of the first light results of the first receivers used in Chile are presented.

Ultra-sensitive superconducting tunnel junction heterodyne receivers used for astronomy research require relatively low levels of local oscillator (LO) power. When configured as an imaging array, however, the LO power required substantially increases and the provision and distribution of a harmonically generated LO signal to multiple pixel elements becomes a technically challenging task. Furthermore, the difficulty of generating LO power is compounded as the operational frequency is increased into the supra-THz region (<1 THz). We will present our programme of research directed towards the provision of future THz astronomy receivers, in which we have been pursuing the development of enhanced harmonic up-conversion LO technology.

We report on the development of Argus, a 16-pixel spectrometer, which will enable fast astronomical imaging over the 85–116 GHz band. Each pixel includes a compact heterodyne receiver module, which integrates two InP MMIC low-noise amplifiers, a coupled-line bandpass filter and a sub-harmonic Schottky diode mixer. The receiver signals are routed to and from the multi-chip MMIC modules with multilayer high frequency printed circuit boards, which includes LO splitters and IF amplifiers. Microstrip lines on flexible circuitry are used to transport signals between temperature stages. The spectrometer frontend is designed to be scalable, so that the array design can be reconfigured for future instruments with hundreds of pixels. Argus is scheduled to be commissioned at the Robert C. Byrd Green Bank Telescope in late 2014. Preliminary data for the first Argus pixels are presented.

The noise temperature of existing radio telescope receivers has actually achieved very low values. In any case, there are other practical ways to increase the observational speed of a single dish antennas without using longer integration time: observe with multi-beam and large bandwidth receiver. In this paper we present the front end and the cryogenic dewar design of the 5 beams FPA double linear polarization receiver for the primary focus of the 64 m Sardinia Radio Telescope.

Challenging the conventional bandwidth limit, we design an extremely wide-band circular waveguide septum polarizer, covering 42% bandwidth, from 77 GHz to 118 GHz, without any high-order resonance. The performance of this polarizer has been verified in between 75 GHz and 115 GHz. The Stokes parameters constructed from the measured data show that the leakages from I to Q are below ±2% and the Q U mutual leakage below ±1%. This result removes the major weakness of the septum polarizer and opens up a new domain of astronomical instrumentation for polarization measurement. Despite this polarizer is designed to cover 77-118 GHz, it can be straightforwardly downsized to cover higher frequencies with minor change. The measurement result of a G-band (140-220 GHz) polarizer is also presented.

We present the latest improvements of lumped element kinetic inductance detectors (LEKIDs) for the NIKA camera at the 30-m telescope of IRAM at Pico Veleta (Spain) [1]. LEKIDs are direct absorption detectors for millimeter wavelength and represent a particularly efficient concept of planar array continuum detectors for the millimeter and submillimeter wavelength range. To improve the detector radiation coupling over a wider frequency range, a combination of backplane reflector and a supplementary layer of dielectric between silicon substrate and backplane has been successfully explored. To this end we apply deep silicon etching to the substrate in order to decrease its effective dielectric constant in an intermediate layer. In the first generation of LEKIDs array, the response is disturbed by the presence of slot-modes in the frequency multiplexing coplanar feed/readout line, an effect which was reduced when applying wire bonding across the readout line. Superconducting air-bridges can be integrated into the array fabrication process. The suppression of slot-modes also reduces undesired cross-talk between pixels. Our current KID detectors are made of very thin aluminum films, but with a thickness of less than 20 nm we have reached some limitations concerning the layout and material processing. Following the results from Leduc et al. [2], we developed non-stoichiometric titanium nitride (TiN) at IRAM as an alternative material. We focus on the work done to achieve reproducible and homogenous films with the required transition temperature for mm-wave detection. We present characterization techniques that allow room temperature measurements to be correlated to the transition temperature of TiN_x and first measurements on a test sample.

In the next decades millimeter and sub-mm astronomy requires large format imaging arrays and broad-band spectrometers to complement the high spatial and spectral resolution of the Atacama Large Millimeter/submillimeter Array. The desired sensors for these instruments should have a background limited sensitivity and a high optical efficiency and enable arrays thousands of pixels in size. Hybrid microwave kinetic inductance detectors consisting of NbTiN and Al have shown to satisfy these requirements. We present the second generation hybrid NbTiN-Al MKIDs, which are photon noise limited in both phase and amplitude readout for loading levels P850GHz < 10 fW. Thanks to the increased responsivity, the photon noise level achieved in phase allows us to simultaneously read out approximately 8000 pixels using state-of-the-art electronics. In addition, the choice of superconducting materials and the use of a Si lens in combination with a planar antenna gives these resonators the flexibility to operate within the frequency range 0:09 < v < 1:1 THz. Given these specifications, hybrid NbTiN-Al MKIDs will enable astronomically usable kilopixel arrays for sub-mm imaging and moderate resolution spectroscopy.

We present the results of a feasibility study, which examined deployment of a ground-based millimeter-wave polarimeter, tailored for observing the cosmic microwave background (CMB), to Isi Station in Greenland. The instrument for this study is based on lumped-element kinetic inductance detectors (LEKIDs) and an F/2.4 catoptric, crossed-Dragone telescope with a 500 mm aperture. The telescope is mounted inside the receiver and cooled to < 4 K by a closed-cycle 4He refrigerator to reduce background loading on the detectors. Linearly polarized signals from the sky are modulated with a metal-mesh half-wave plate that is rotated at the aperture stop of the telescope with a hollow-shaft motor based on a superconducting magnetic bearing. The modular detector array design includes at least 2300 LEKIDs, and it can be configured for spectral bands centered on 150 GHz or greater. Our study considered configurations for observing in spectral bands centered on 150, 210 and 267 GHz. The entire polarimeter is mounted on a commercial precision rotary air bearing, which allows fast azimuth scan speeds with negligible vibration and mechanical wear over time. A slip ring provides power to the instrument, enabling circular scans (360 degrees of continuous rotation). This mount, when combined with sky rotation and the latitude of the observation site, produces a hypotrochoid scan pattern, which yields excellent cross-linking and enables 34% of the sky to be observed using a range of constant elevation scans. This scan pattern and sky coverage combined with the beam size (15 arcmin at 150 GHz) makes the instrument sensitive to 5 < ` < 1000 in the angular power spectra.

The Atacama B-mode Search (ABS), which began observations in February of 2012, is a crossed-Dragone telescope located at an elevation of 5190 m in the Atacama Desert in Chile. ABS is searching for the B-mode polarization spectrum of the cosmic microwave background (CMB) at large angular scales from multipole moments of ` ~ 50 ~ 500, a range that includes the primor- dial B-mode peak from inflationary gravity waves at ~ 100. The ABS focal plane consists of 240 pixels sensitive to 145 GHz, each containing two transition-edge sensor bolometers coupled to orthogonal polarizations with a planar ortho-mode transducer. An ambient-temperature con- tinuously rotating half-wave plate and 4 K optics make the ABS instrument unique. We discuss the characterization of the detector spectral responses with a Fourier transform spectrometer and demonstrate that the pointing model is adequate. We also present measurements of the beam from point sources and compare them with simulations.

ACTPol is the polarization-sensitive receiver on the Atacama Cosmology Telescope. ACTPol enables sensitive millimeter wavelength measurements of the temperature and polarization anisotropies of the Cosmic Microwave Background (CMB) at arcminute angular scales. These measurements are designed to explore the process of cosmic structure formation, constrain or determine the sum of the neutrino masses, probe dark energy, and provide a foundation for a host of other cosmological tests. We present an overview of the first season of ACTPol observations focusing on the optimization and calibration of the first detector array as well as detailing the on-sky performance.

EBEX is a balloon-borne telescope designed to measure the polarization of the cosmic microwave background radiation. During its eleven day science flight in the Austral Summer of 2012, it operated 955 spider-web transition edge sensor (TES) bolometers separated into bands at 150, 250 and 410 GHz. This is the first time that an array of TES bolometers has been used on a balloon platform to conduct science observations. Polarization sensitivity was provided by a wire grid and continuously rotating half-wave plate. The balloon implementation of the bolometer array and readout electronics presented unique development requirements. Here we present an outline of the readout system, the remote tuning of the bolometers and Superconducting QUantum Interference Device (SQUID) amplifiers, and preliminary current noise of the bolometer array and readout system.

Searching for evidence of inflation by measuring B-modes in the cosmic microwave background (CMB) polarization at degree angular scales remains one of the most compelling experimental challenges in cosmology. BICEP2 and the Keck Array are part of a program of experiments at the South Pole whose main goal is to achieve the sensitivity and systematic control necessary for measurements of the tensor-to-scalar ratio at σ(r) ~0:01. Beam imperfections that are not sufficiently accounted for are a potential source of spurious polarization that could interfere with that goal. The strategy of BICEP2 and the Keck Array is to completely characterize their telescopes' polarized beam response with a combination of in-lab, pre-deployment, and on-site calibrations. We Sereport the status of these experiments, focusing on continued improved understanding of their beams. Far-field measurements of the BICEP2 beam with a chopped thermal source, combined with analysis improvements, show that the level of residual beam-induced systematic errors is acceptable for the goal of σ(r) ~ 0:01 measurements. Beam measurements of the Keck Array side lobes helped identify a way to reduce optical loading with interior cold baffles, which we installed in late 2013. These baffles reduced total optical loading, leading to a ~ 10% increase in mapping speed for the 2014 observing season. The sensitivity of the Keck Array continues to improve: for the 2013 season it was 9:5 μK _/s noise equivalent temperature (NET). In 2014 we converted two of the 150-GHz cameras to 100 GHz for foreground separation capability. We have shown that the BICEP2 and the Keck Array telescope technology is sufficient for the goal of σ(r) ~ 0:01 measurements. Furthermore, the program is continuing with BICEP3, a 100-GHz telescope with 2560 detectors.

We present the results of integration and characterization of the Spider instrument after the 2013 pre-flight campaign. Spider is a balloon-borne polarimeter designed to probe the primordial gravitational wave signal in the degree-scale B-mode polarization of the cosmic microwave background. With six independent telescopes housing over 2000 detectors in the 94 GHz and 150 GHz frequency bands, Spider will map 7.5% of the sky with a depth of 11 to 14 μK•arcmin at each frequency, which is a factor of ~5 improvement over Planck. We discuss the integration of the pointing, cryogenic, electronics, and power sub-systems, as well as pre-flight characterization of the detectors and optical systems. Spider is well prepared for a December 2014 flight from Antarctica, and is expected to be limited by astrophysical foreground emission, and not instrumental sensitivity, over the survey region.

This paper presents the key findings of an ESA-funded programme of work to investigate refractive systems and their application to precision polarimetry experiments. We briefly summarize the derivation of requirements on the optical system for CMB polarimetry, and the design of a refractive telescope system which meets these stringent requirements. An extensive programme of experimental work was undertaken in order to better understand the optical, thermal and mechanical characteristics of the lens material, and of lenses made from this material. A repeatable and controllable antireflection coating procedure was developed and validated, and used to coat lenses used in this study. Optical measurements before and after coating have been used to validate a new module for an industry-standard antenna modelling software package.

Astronomical observations in the far-infrared are critical for investigation of cosmic microwave background (CMB) radiation and the formation and evolution of planets, stars and galaxies. In the case of space telescope receivers, a strong heritage exists for corrugated horn antenna feeds to couple the far-infrared signals to the detectors mounted in a waveguide or cavity structure. Such antenna feeds have been utilized, for example, in the Planck satellite in both single-mode channels for the observation of the CMB and the multi-mode channels optimized for the detection of foreground sources. Looking to the demands of the future space missions, it is clear that the development of new technology solutions for the optimization and simplification of horn antenna structures will be required for large arrays. Horn antennas will continue to offer excellent control of beam and polarization properties for CMB polarisation experiments satisfying stringent requirements on low sidelobe levels, symmetry, and low cross polarization in large arrays. Similarly for far infrared systems, multi-mode horn and waveguide cavity structures are proposed to enhance optical coupling of weak signals for cavity coupled bolometers. In this paper we present a computationally efficient approach for modelling and optimising horn character-istics. We investigate smooth-walled horns that have an equivalent optical performance to that of corrugated horns traditionally used for CMB measurements. We discuss the horn optimisation process and the algorithms available to maximise performance of a merit parameter such as low cross polarisation or high Gaussicity. A single moded horn resulting from this design process has been constructed and experimentally verified in the W band. The results of the measurement campaign are presented in this paper and compared to the simulated results, showing a high level of agreement in co and cross polarisation radiation patterns, with low levels of integrated cross polar power. For future Far IR receivers using waveguide bounded bolometers and absorbers, an optimisation of the waveg-uide structures and absorber location within the integrating cavity is critical to maximise coupling performance particularly for multimoded systems. We outline the benefit of using multi-moded horns in focal plane arrays and illustrate the increased optical sensitivity associated with a many-moded approach, which may be optimized for coupling to particular incident beams.

The successful European Space Agency (ESA) Planck mission has mapped the Cosmic Microwave Background (CMB) temperature anisotropy with unprecedented accuracy. However, Planck was not designed to detect the polarised components of the CMB with comparable precision. The BICEP2 collaboration has recently reported the first detection of the B-mode polarisation. ESA is funding the development of critical enabling technologies associated with B-mode polarisation detection, one of these being large diameter half-wave plates. We compare different polarisation modulators and discuss their respective trade-offs in terms of manufacturing, RF performance and thermo-mechanical properties. We then select the most appropriate solution for future satellite missions, optimized for the detection of B-modes.

The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission to characterize the cosmic microwave background (CMB). PIXIE will map linear polarization on degree angular scales and larger to search for the gravity-wave signature of primordial inflation, and measure distortions from the blackbody spectrum to constrain energy-releasing processes in the early universe. PIXIE uses multi-moded optics to achieve sensitivity comparable to a kilo-pixel focal plane of diffraction-limited detectors, but using only 4 semiconductor bolometers illuminated by a non-imaging feed horn. PIXIE's frequency coverage extends from 30 GHz to 6 THz. Although the co- and cross-polar response of the feed horn and coupling optics is easily evaluated in the short-wavelength (geometric optics) limit, the response at longer wavelengths is more difficult to model analytically. We have built a coupled feed horn/reflector optical system based on the PIXIE design and measured the co- and cross-polar response at several wavelengths spanning the transition from the few-mode limit at long wavelengths to the geometric optics limit at short wavelengths. We compare the measured co- and cross-polar beam patterns to model predictions and discuss the implications for the PIXIE mission and similar missions using multi-moded optics.

ArTeMiS is a submillimeter camera planned to work simultaneously at 450 μm, 350 μm and 200 μm by use of 3 focal planes of, respectively, 8, 8 and 4 bolometric arrays, each one made of 16 x18 pixels. In July 2013, with a preliminary setting reduced to 4 modules and to the 350 μm band, ArTeMiS was installed successfully at the Cassegrain focus of APEX, a 12 m antenna located on the Chajnantor plateau, Chile. After the summary of the scientific requirements, we describe the main lines of the ArTeMiS nominal optical design with its rationale and performances. This optical design is highly constrained by the room allocation available in the Cassegrain cabin. It is an all-reflective design including a retractable pick off mirror, a warm Fore Optics to image the focal plane of the telescope inside the cryostat, and the cold optics. The large size of the field of view at the focal plane of the telescope, 72 mm x 134 mm for the 350 μm and 450 μm beams, leads to the use of biconical toroidal mirrors. In this way, the nominal image quality obtained on the bolometric arrays is only just diffraction limited at some corners of the field of view. To keep a final PSF as much uniform as possible across the field of view, we have used the technic of manufacturing by diamond turning to machine the mirrors. This approach, while providing high accuracy on the shape of the mirrors, made easier the control of the two sub units, the Fore Optics and the cold optics, in the visible domain and at room temperature. Moreover, the use of the similar material (Aluminium alloy 6061) for the optical bench and the mirrors with their mount ensures a homothetic shrinking during the cooling down. The alignment protocol, drew up at the early step of the study, is also presented. It required the implementation of two additional mechanisms inside the cryostat to check the optical axis of the cold optics, in the real conditions of operation of ArTeMiS. In this way, it was possible to pre-align the Fore Optics sub unit with respect to the cold optics. Finally, despite the high constraints of the operating conditions of APEX, this protocol allowed to align ArTeMiS with respect to the telescope in a single adjustment. The first images obtained on the sky, Saturn with its rings, are given.

Frequency domain multiplexing (fMux) is an established technique for the readout of transition-edge sensor (TES) bolometers in millimeter-wavelength astrophysical instrumentation. In fMux, the signals from multiple detectors are read out on a single pair of wires reducing the total cryogenic thermal loading as well as the cold component complexity and cost of a system. The current digital fMux system, in use by POLARBEAR, EBEX, and the South Pole Telescope, is limited to a multiplexing factor of 16 by the dynamic range of the Superconducting Quantum Interference Device pre-amplifier and the total system bandwidth. Increased multiplexing is key for the next generation of large format TES cameras, such as SPT-3G and POLARBEAR2, which plan to have on the of order 15,000 detectors. Here, we present the next generation fMux readout, focusing on the warm electronics. In this system, the multiplexing factor increases to 64 channels per module (2 wires) while maintaining low noise levels and detector stability. This is achieved by increasing the system bandwidth, reducing the dynamic range requirements though active feedback, and digital synthesis of voltage biases with a novel polyphase filter algorithm. In addition, a version of the new fMux readout includes features such as low power consumption and radiation-hard components making it viable for future space-based millimeter telescopes such as the LiteBIRD satellite.

For the next generation of Cosmic Microwave Background (CMB) experiments, kilopixel arrays of Transition Edge Sensor (TES) bolometers are necessary to achieve the required sensitivity and their science goals. We are developing read-out electronics for POLARBEAR-2 CMB experiment, which multiplexes 32-TES bolometers through a single superconducting quantum interface device (SQUID). To increase both the bandwidth of the SQUID electronics and the multiplexing factor, we are modifying cold wiring and developing LC filters, and a low-inductance superconducting cable. Using these components, we will show frequency domain multiplexing up to 3 MHz.

For the read out of the Transition Edge Sensors (TES) bolometer arrays of the SAFARI instrument on the Japanese background-limited far-IR SPICA mission SRON is developing a Frequency Domain Multiplexing (FDM) read-out system. The next step after the successful demonstration of the read out of 38 TES bolometers using FDM was to demonstrate the FDM readout of the required 160 TES bolometers. Of the 160 LC filter and TES bolometer chains 151 have been connected and after cooldown 148 of the resonances could be identified. Although initial operation and locking of the pixels went smoothly the experiment revealed several complications. In this paper we describe the 160 pixel FDM set-up, show the results and discuss the issues faced during operation of the 160 pixel FDM experiment.

The Simons Array is an expansion of the POLARBEAR cosmic microwave background (CMB) polarization experiment currently observing from the Atacama Desert in Northern Chile. This expansion will create an array of three 3.5m telescopes each coupled to a multichroic bolometric receiver. The Simons Array will have the sensitivity to produce a ≥ 5σ detection of inationary gravitational waves with a tensor-to-scalar ratio r ≥ 0:01, detect the known minimum 58 meV sum of the neutrino masses with 3σ confidence when combined with a next-generation baryon acoustic oscillation measurement, and make a lensing map of large-scale structure over the 80% of the sky available from its Chilean site. These goals require high sensitivity and the ability to extract the CMB signal from contaminating astrophysical foregrounds; these requirements are met by coupling the three high-throughput telescopes to novel multichroic lenslet-coupled pixels each measuring CMB photons in both linear polarization states over multiple spectral bands. We present the status of this instrument already under construction, and an analysis of its capabilities.

Future cosmology space missions will concentrate on measuring the polarization of the Cosmic Microwave Back- ground, which potentially carries invaluable information about the earliest phases of the evolution of our universe. Such ambitious projects will ultimately be limited by the sensitivity of the instrument and by the accuracy at which polarized foreground emission from our own Galaxy can be subtracted out. We present the PILOT balloon project which will aim at characterizing one of these foreground sources, the polarization of the dust continuum emission in the diffuse interstellar medium. The PILOT experiment will also constitute a test-bed for using multiplexed bolometer arrays for polarization measurements. We present the results of ground tests obtained just before the first flight of the instrument.

The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to measure the signature of a gravitationalwave background from inflation in the polarization of the cosmic microwave background (CMB). CLASS is a multi-frequency array of four telescopes operating from a high-altitude site in the Atacama Desert in Chile. CLASS will survey 70% of the sky in four frequency bands centered at 38, 93, 148, and 217 GHz, which are chosen to straddle the Galactic-foreground minimum while avoiding strong atmospheric emission lines. This broad frequency coverage ensures that CLASS can distinguish Galactic emission from the CMB. The sky fraction of the CLASS survey will allow the full shape of the primordial B-mode power spectrum to be characterized, including the signal from reionization at low ɺ. Its unique combination of large sky coverage, control of systematic errors, and high sensitivity will allow CLASS to measure or place upper limits on the tensor-to-scalar ratio at a level of r = 0:01 and make a cosmic-variance-limited measurement of the optical depth to the surface of last scattering, Ƭ .

The Cosmology Large Angular Scale Surveyor (CLASS) experiment aims to map the polarization of the Cosmic Microwave Background (CMB) at angular scales larger than a few degrees. Operating from Cerro Toco in the Atacama Desert of Chile, it will observe over 65% of the sky at 38, 93, 148, and 217 GHz. In this paper we discuss the design, construction, and characterization of the CLASS 38 GHz detector focal plane, the first ever Q-band bolometric polarimeter array.

The Primordial Inflation Polarization Explorer (Piper) is a balloon-borne cosmic microwave background (CMB) polarimeter designed to search for evidence of inflation by measuring the large-angular scale CMB polarization signal. Bicep2 recently reported a detection of B-mode power corresponding to the tensor-to-scalar ratio r = 0:2 on 2 degree scales. If the Bicep2 signal is caused by inflationary gravitational waves (IGWs), then there should be a corresponding increase in B-mode power on angular scales larger than 18 degrees. Piper is currently the only suborbital instrument capable of fully testing and extending the Bicep2 results by measuring the B-mode power spectrum on angular scales ϴ =~0:6° to 90°, covering both the reionization bump and recombination peak, with sensitivity to measure the tensor-to-scalar ratio down to r = 0:007, and four frequency bands to distinguish foregrounds. Piper will accomplish this by mapping 85% of the sky in four frequency bands (200, 270, 350, 600 GHz) over a series of 8 conventional balloon flights from the northern and southern hemispheres. The instrument has background-limited sensitivity provided by fully cryogenic (1.5 K) optics focusing the sky signal onto four 32x40-pixel arrays of time-domain multiplexed Transition-Edge Sensor (TES) bolometers held at 140 mK. Polarization sensitivity and systematic control are provided by front-end Variable- delay Polarization Modulators (VPMs), which rapidly modulate only the polarized sky signal at 3 Hz and allow Piper to instantaneously measure the full Stokes vector (I; Q;U; V ) for each pointing. We describe the Piper instrument and progress towards its first flight.

Bicep3 is a 550 mm-aperture refracting telescope for polarimetry of radiation in the cosmic microwave background at 95 GHz. It adopts the methodology of Bicep1, Bicep2 and the Keck Array experiments | it possesses sufficient resolution to search for signatures of the inflation-induced cosmic gravitational-wave background while utilizing a compact design for ease of construction and to facilitate the characterization and mitigation of systematics. However, Bicep3 represents a significant breakthrough in per-receiver sensitivity, with a focal plane area 5x larger than a Bicep2/Keck Array receiver and faster optics (f=1:6 vs. f=2:4). Large-aperture infrared-reflective metal-mesh filters and infrared-absorptive cold alumina filters and lenses were developed and implemented for its optics. The camera consists of 1280 dual-polarization pixels; each is a pair of orthogonal antenna arrays coupled to transition-edge sensor bolometers and read out by multiplexed SQUIDs. Upon deployment at the South Pole during the 2014-15 season, Bicep3 will have survey speed comparable to Keck Array 150 GHz (2013), and will signifcantly enhance spectral separation of primordial B-mode power from that of possible galactic dust contamination in the Bicep2 observation patch

We describe the design of a new polarization sensitive receiver, spt-3g, for the 10-meter South Pole Telescope (spt). The spt-3g receiver will deliver a factor of ~20 improvement in mapping speed over the current receiver, spt-pol. The sensitivity of the spt-3g receiver will enable the advance from statistical detection of B-mode polarization anisotropy power to high signal-to-noise measurements of the individual modes, i.e., maps. This will lead to precise (~0.06 eV) constraints on the sum of neutrino masses with the potential to directly address the neutrino mass hierarchy. It will allow a separation of the lensing and inflationary B-mode power spectra, improving constraints on the amplitude and shape of the primordial signal, either through spt-3g data alone or in combination with bicep2/keck, which is observing the same area of sky. The measurement of small-scale temperature anisotropy will provide new constraints on the epoch of reionization. Additional science from the spt-3g survey will be significantly enhanced by the synergy with the ongoing optical Dark Energy Survey (des), including: a 1% constraint on the bias of optical tracers of large-scale structure, a measurement of the differential Doppler signal from pairs of galaxy clusters that will test General Relativity on ~200Mpc scales, and improved cosmological constraints from the abundance of clusters of galaxies

Terahertz high-resolution spectroscopy of interstellar molecular clouds greatly relies on hot-electron superconducting bolometric (HEB) mixers. Current state-of-the-art receivers use mixer devices made from ultrathin (~ 3-5 nm) films of NbN with critical temperature ~ 9-11 K. Such mixers have been deployed on a number of groundbased, suborbital, and orbital platforms including the HIFI instrument on the Hershel Space Observatory. Despite its good sensitivity and well-established fabrication process, the NbN HEB mixer suffers from the narrow intermediate frequency (IF) bandwidth ~ 2-3 GHz and is limited to operation at liquid Helium temperature. As the heterodyne receivers are now trending towards “high THz” frequencies, the need in a larger IF bandwidth becomes more pressing since the same velocity resolution for a Doppler shifted line at 5 THz requires a 5-times greater IF bandwidth than at 1 THz. Our work is focusing on the realization of practical HEB mixers using ultrathin (10-20 nm) MgB₂ films. They are prepared using a Hybrid Physical-Chemical Vapor Deposition (HPCVD) process yielding ultrathin films with critical temperature ~ 37-39 K. The expectation is that the combination of small thickness, high acoustic phonon transparency at the interface with the substrate, and very short electron-phonon relaxation time may lead to IF bandwidth ~ 10 GHz or even higher. SiC continues to be the most favorable substrate for MgB₂ growth and as a result, a study has been conducted on the transparency of SiC at THz frequencies. FTIR measurements show that semi-insulating SiC substrates are at least as transparent as Si up to 2.5 THz. Currently films are passivated using a thin (10 nm) SiO2 layer which is deposited ex-situ via RF magnetron sputtering. Micron-sized spiral antenna-coupled HEB mixers have been fabricated using MgB2 films as thin as 10 nm. Fabrication was done using contact UV lithography and Ar Ion milling, with E-beam evaporated Au films deposited for the antenna. Measurements have been carried out on these devices in the DC, Microwave, and THz regimes. The devices are capable of mixing signals above 20 K indicating that operation may be possible using a cryogen-free cooling system. We will report the results of all measurements taken to indicate the local oscillator power requirements and the IF bandwidth of MgB₂ HEB mixers.

We report on the performance of a high sensitivity 4.7 THz heterodyne receiver based on a NbN hot electron bolometer mixer and a quantum cascade laser (QCL) as local oscillator. The receiver is developed to observe the astronomically important neutral atomic oxygen [OI] line at 4.7448 THz on a balloon based telescope. The single-line frequency control and improved beam pattern of QCL have taken advantage of a third-order distributed feedback structure. We measured a double sideband receiver noise temperature (T_rec(DSB)) of 815 K, which is ~ 7 times the quantum noise limit (hν/2kB). An Allan time of 15 s at an effective noise fluctuation bandwidth of 18 MHz is demonstrated. Heterodyne performance was further supported by a measured methanol line spectrum around 4.7 THz.

CNES (French Space Agency) continuously drives the development of detectors for Space based Astronomy. Several detector concepts are developped by French Laboratories, from far infrared to mm wavelength. This paper gives a status on these developments as well as an overview of the associated roadmap.

The Greenland Telescope project will deploy and operate a 12m sub-millimeter telescope at the highest point of the Greenland i e sheet. The Greenland Telescope project is a joint venture between the Smithsonian As- trophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA). In this paper we discuss the concepts, specifications, and science goals of the instruments being developed for single-dish observations with the Greenland Telescope, and the coupling optics required to couple both them and the mm-VLBI receivers to antenna. The project will outfit the ALMA North America prototype antenna for Arctic operations and deploy it to Summit Station,1 a NSF operated Arctic station at 3,100m above MSL on the Greenland I e Sheet. This site is exceptionally dry, and promises to be an excellent site for sub-millimeter astronomical observations. The main science goal of the Greenland Telescope is to carry out millimeter VLBI observations alongside other telescopes in Europe and the Americas, with the aim of resolving the event horizon of the super-massive black hole at the enter of M87. The Greenland Telescope will also be outfitted for single-dish observations from the millimeter-wave to Tera-hertz bands. In this paper we will discuss the proposed instruments that are currently in development for the Greenland Telescope - 350 GHz and 650 GHz heterodyne array receivers; 1.4 THz HEB array receivers and a W-band bolometric spectrometer. SAO is leading the development of two heterodyne array instruments for the Greenland Telescope, a 48- pixel, 325-375 GHz SIS array receiver, and a 4 pixel, 1.4 THz HEB array receiver. A key science goal for these instruments is the mapping of ortho and para H2D+ in old protostellar ores, as well as general mapping of CO and other transitions in molecular louds. An 8-pixel prototype module for the 350 GHz array is currently being built for laboratory and operational testing on the Greenland Telescope. Arizona State University are developing a 650 GHz 256 pixel SIS array receiver based on the KAPPa SIS mixer array technology and ASIAA are developing 1.4 THz HEB single pixel and array receivers. The University of Cambridge and SAO are collaborating on the development of the CAMbridge Emission Line Surveyor (CAMELS), a W-band `on- hip' spectrometer instrument with a spectral resolution of R ~ 3000. CAMELS will consist of two pairs of horn antennas, feeding super conducting niobium nitride filter banks read by tantalum based Kinetic Inductance Detectors.

TIME-Pilot is designed to make measurements from the Epoch of Reionization (EoR), when the first stars and galaxies formed and ionized the intergalactic medium. This will be done via measurements of the redshifted 157.7 um line of singly ionized carbon ([CII]). In particular, TIME-Pilot will produce the first detection of [CII] clustering fluctuations, a signal proportional to the integrated [CII] intensity, summed over all EoR galaxies. TIME-Pilot is thus sensitive to the emission from dwarf galaxies, thought to be responsible for the balance of ionizing UV photons, that will be difficult to detect individually with JWST and ALMA. A detection of [CII] clustering fluctuations would validate current theoretical estimates of the [CII] line as a new cosmological observable, opening the door for a new generation of instruments with advanced technology spectroscopic array focal planes that will map [CII] fluctuations to probe the EoR history of star formation, bubble size, and ionization state. Additionally, TIME-Pilot will produce high signal-to-noise measurements of CO clustering fluctuations, which trace the role of molecular gas in star-forming galaxies at redshifts 0 < z < 2. With its unique atmospheric noise mitigation, TIME-Pilot also significantly improves sensitivity for measuring the kinetic Sunyaev-Zel’dovich (kSZ) effect in galaxy clusters. TIME-Pilot will employ a linear array of spectrometers, each consisting of a parallel-plate diffraction grating. The spectrometer bandwidth covers 185-323 GHz to both probe the entire redshift range of interest and to include channels at the edges of the band for atmospheric noise mitigation. We illuminate the telescope with f/3 horns, which balances the desire to both couple to the sky with the best efficiency per beam, and to pack a large number of horns into the fixed field of view. Feedhorns couple radiation to the waveguide spectrometer gratings. Each spectrometer grating has 190 facets and provides resolving power above 100. At this resolution, the longest dimension of the grating is 31 cm, which allows us to stack gratings in two blocks (one for each polarization) of 16 within a single cryostat, providing a 1x16 array of beams in a 14 arcminute field of view. Direct absorber TES sensors sit at the output of the grating on six linear facets over the output arc, allowing us to package and read out the detectors as arrays in a modular manner. The 1840 detectors will be read out with the NIST time-domain-multiplexing (TDM) scheme and cooled to a base temperature of 250 mK with a 3He sorption refrigerator. We present preliminary designs for the TIME-Pilot cryogenics, spectrometers, bolometers, and optics.

We present the result of a design study for X-Spec, a multi-beam, R=400{700 survey spectrometer covering 190{520 GHz under development for CCAT. It is designed to measure the bright atomic fine-structure and molecular rotational transitions that cool galaxies' interstellar gas, in particular, the 158 um rest-frame [CII] transition, in thousands to tens of thousands of galaxies ranging from z=9 to z=3.5. With the wide bandwidth and multi-object capability, X-Spec / CCAT will be more powerful than ALMA for redshift-blind galaxy surveys and tomographic intensity mapping. X-Spec uses SuperSpec filterbank spectrometer technology with TiN KIDs described by Hailey-Dunsheath et al. in this conference. Because the density of sources is small, galaxy follow-up will be most efficient with a front-end steering unit which we have prototyped, also described in a separate paper (Chapman et al. in this conference). Our baseline instrument concept has 84 steered beams arrayed over the 1 degree CCAT field, each beam couples to 4 chips (2 bands x 2 polarizations) each chip with approximately 500 detectors, making a total of -170,000 KIDs in the full instrument. A direct imaging spectrometer (integral-field spectrometer) with a comparably-sized backend is also considered.

Astronomical surveys are demanding more throughput from telescope receivers. Currently, microwave/millimeter telescopes with mature cryogenic single pixel receivers are upgrading to multi-pixel receivers by replacing the conventional feed horns with phased array feeds (PAFs) to increase the field of view and, thus, imaging speeds. This step in astronomy instrumentation has been taken by only a few research laboratories world-wide and primarily in Lband (0.7-1.5 GHz). We present a K-band (18-26 GHz) 5x5 modular PAF to demonstrate the feasibility of higher frequency receiving arrays. The KPAF system includes a tapered slot antenna array, a cryogenic commercial GaAs MMIC amplifier block, and a mixing stage to down-convert to L band for an existing beamformer. The noise temperature and power budget are outlined. Full antenna S-parameters and far-field beam patterns are simulated and measured using both planar near-field and far-field techniques. Cryogenic and room temperature amplifier noise measurements with varying bias levels are presented.

A two arm, opto-mechanical positioner mechanism is presented in this proceedings as a candidate steering system for the millimeter-wave XSPEC spectrograph. The design is well matched to the expected target density on the sky, and meeting all requirements of the Cerro Chajnantor Atacama Telescope (CCAT), site environmental conditions (e.g., operating temperature and power dissipation), and the positioning requirements themselves for acquiring and tracking astronomical objects whose light is fed into the XSPEC spectrograph units. The prototype design has been fabricated and tested for basic operations.

Many applications in cosmology and astrophysics at millimeter wavelengths — CMB polarization, studies of galaxy clusters using the Sunyaev-Zeldovich effect, studies of star formation at high redshift and in our local universe and our galaxy— require large-format arrays of millimeter-wave detectors. Feedhorn, lens-coupled twinslot antenna, and phased-array antenna architectures for receiving mm-wave light present numerous advantages for control of systematics and for simultaneous coverage of both polarizations and/or multiple spectral bands. Simultaneously, kinetic inductance detectors using high-resistivity materials like titanium nitride are an attractive sensor option for large-format arrays because they are highly multiplexable and because their high responsivity can render two-level-system noise subdominant to photon and recombination noise. However, coupling the two is a challenge because of the impedance mismatch between the microstrip exiting these architectures and the high resistivity of titanium nitride. Mitigating direct absorption in the KID is also a challenge. We present a detailed titanium nitride KID design that addresses these challenges. The KID inductor is capacitively coupled to the microstrip in such a way as to form a lossy termination without creating an impedance mismatch. A parallelplate capacitor design mitigates direct absorption, uses hydrogenated amorphous silicon, and yields acceptable two-level-system noise. We show that an optimized design can yield expected sensitivities very close to the fundamental limit from photon and recombination noises for two relevant examples: single spectral band designs appropriate for 90 and 150 GHz for CMB polarization and a multi-spectral-band design that covers 90 GHz to 405 GHz in six bands for SZ effect studies.

We present the latest commissioning results and instrument performance for the SCUBA-2 imaging Fourier Transform Spectrometer (FTS-2) installed at the James Clerk Maxwell Telescope (JCMT). This ancillary instrument provides intermediate spectral resolution (R ~10 to 5000) across both the 450 and 850 μm atmospheric transmission windows with a FOV of ~5 arcmin². The superconducting TES sensors and SQUID readout of SCUBA-2 present unique challenges for operation of an FTS; the sensitivity requirements demand high detector linearity and stability in addition to control of systematic atmospheric and optical spillover effects. We discuss the challenges encountered during commissioning and ongoing efforts to mitigate their effects.

SCUBA-2 is a wide-field submillimeter bolometer camera operating at the James Clerk Maxwell Telescope. The camera has twin focal planes, each with 5120 superconducting Transition Edge Sensors, which provide simultaneous images in two filter bands at 450 and 850 microns matched to the atmospheric windows. Detailed knowledge of the optical filter profiles that define these bands is important for estimating potential contamination from the prevalent CO J = 3-2 and CO 6-5 line emission, and correctly interpreting the effects of the source spectral index on photometric observations. We present measurements of the spectral response of SCUBA-2 obtained with FTS-2, the ancillary Fourier transform spectrometer instrument at the JCMT. The spectral measurements will be compared with the predicted filter profile determined from the linear combination of the individual filter profiles present in the SCUBA-2 optical train.

A new photonic camera has been developed in the framework of the ArTéMis project (Bolometers architecture for large field of view ground based telescopes in the sub-millimeter). This camera scans the sky in the sub-millimeter range at simultaneously three different wavelengths, namely 200 μm, 350 μm, 450 μm, and is installed inside the APEX telescope located at 5100m above sea level in Chile. Bolometric detectors cooled to 300 mK are used in the camera, which is integrated in an original cryostat developed at the low temperature laboratory (SBT) of the INAC institut. This cryostat contains filters, optics, mirrors and detectors which have to be implemented according to mass, size and stiffness requirements. As a result the cryostat exhibits an unusual geometry. The inner structure of the cryostat is a 40 K plate which acts as an optical bench and is bound to the external vessel through two hexapods, one fixed and the other one mobile thanks to a ball bearing. Once the cryostat is cold, this characteristic enabled all the different elements to be aligned with the optical axis. The cryogenic chain is built around a pulse tube cooler (40 K and 4 K) coupled to a double stage helium sorption cooler (300 mK). The cryogenic and vacuum processes are managed by a Siemens PLC and all the data are showed and stored on a CEA SCADA system. This paper describes the mechanical and thermal design of the cryostat, its command control, and the first thermal laboratory tests. This work was carried out in collaboration with the Astrophysics laboratory SAp of the IRFU institut. SAp and SBT have installed the camera in July 2013 inside the Cassegrain cabin of APEX.

ArTeMiS is a sub-millimetre camera to be operated, on the Atacama Pathfinder Experiment Telescope (APEX). The ultimate goal is to observe simultaneously in three atmospheric spectral windows in the region of 200, 350 and 450 microns. We present the filtering scheme, which includes the cryostat window, thermal rejection elements, band separation and spectral isolation, which has been adopted for this instrument. This was achieved using a combination of scattering, Yoshinaga filters, organic dyes and Ulrich type embedded metallic mesh devices. Design of the quasi-optical mesh components has been developed by modelling with an in-house developed code. For the band separating dichroics, which are used with an incidence angle of 35 deg, further modelling has been performed with HFSS (Ansoft). Spectral characterization of the components for the 350 and 450 bands have been performed with a Martin-Puplett Polarizing Fourier Transform Spectrometer. While for the first commissioning and observation campaign, one spectral band only was operational (350 microns), we report on the design of the 200, 350 and 450 micron bands.

CCAT1 is a submillimeter telescope currently under development that will be located at an altitude of 5600 meters in the Andes mountains of northern Chile. The atmospheric transmission at this site will allow CCAT to achieve high sensitivity over a wide field of view and a broad wavelength range to provide an unprecedented capability for deep, large area multicolor submillimeter surveys. In order to achieve high aperture efficiencies out to frequencies of ~ 1 THz, the 162 individual panels that form the 25 meter aperture of CCAT must be aligned to a tolerance of a few microns rms. The design of a wavefront sensor to achieve this goal is presented.

The 1.1 THz multi-pixel heterodyne receiver will be mounted in the Nasmyth A cabin of the 12 m APEX telescope on the Chajnantor plateau, 5000 meters altitude in northern Chile. The receiver will cover the spectral window of 1000 - 1080 GHz, where important spectral lines like CO 9-8 at 1036.9 GHz, a tracer of warm and dense gas and OH+ at 1033 GHz and NH+ at 1012.6 GHz, both important for the study of chemical networks in the ISM, are located. The multi-pixel receiver greatly enhances the science output under the difficult observing conditions in this frequency range. Two 9-pixel focal plane sub-arrays on orthogonal polarizations are installed in easily removable cartridges. We developed a new thermal link to connect the cartridges to the cryostat. Our thermal link is an all-metal design: aluminum and Invar. All the optics is fully reflective, thus avoiding the absorption and reflection losses of dielectric lenses and reducing standing waves in the receiver. To guaranty internal optics alignment, we employ a monolithic integrated optics approach for the cold optics and the Focal Plane Unit (FPU) optics modeled after the CHARM (Compact Heterodyne Array Receiver Module) concept. The receiver uses synthesizer-driven solid-state local oscillators (LO) and the mixers will be balanced SIS mixers, which are essentially based on the design of the on-chip balanced SIS mixers at 490 GHz developed in our institute. Singleended HEB mixers are used for the laboratory tests of the optics. The LO power distribution is accommodated behind the FPU optics. It is composed of the LO optics, which includes a collimating Fourier grating, and an LO distribution plate to supply LO signal to each of the 9 pixels of the sub-array. Different options for the LO coupling design and fabrication are being analyzed and will be based on in-house hybrid waveguide/planar technology. We summarize the receiver project with emphasis on the cryogenics and the optics and present laboratory test results of the cryogenics, including the thermal link's performance. Beam pattern measurements of the receiver optics are scheduled for the coming days, but unfortunately could not be included in the current paper.

We present the design of a cryogenic system for testing different technologies of millimeter wavelength detectors. The proposed design is developed at the Astronomical Instrumentation Laboratory for Millimeter Wavelength at the National Institute of Astrophysics, Optics and Electronics, in México. The cryogenic system is integrated by a closed cycle pulse tube cooler with a 4 Kelvin 12 inches cold plate and a He-4/He-3 fridge and would be able to characterize KIDs (Kinetic Inductor Detectors), TES (Transition Edge Sensors) or semiconductor bolometers using a thermal link to a 250 mK stage. Readout electronics will be installed at the 4 Kelvin cold plate along with connectors and cables for the thermometry. In this paper we present a preliminary 3D model design which its main goal is to use efficiently the limited space in the cryostat with emphasis on the interchangeability for installing each time any of the three different detector technologies in the same cold plate; results for the thermal calculations and finite-element modeling are also shown. The system would allow, with some minor changes, to replace the He-4/He-3 fridge by a dilution fridge in order to reach temperatures about 100 mK to have more flexibility in the detector testing. The importance of the cryogenic test bench relies in the need for an easier and quicker characterization of detectors arrays as part of the research for the development of instruments for millimeter telescopes.

There have been several exciting developments in the technologies commonly used n in the hardware hacking community. Advances in low cost additive-manufacturing processes (i.e. 3D-printers) and the development of openhardware projects, which have produced inexpensive and easily programmable micro-controllers and micro-computers (i.e. Arduino and Raspberry Pi) have opened a new door for individuals seeking to make their own devices. Here we describe the potential for these technologies to reduce costs in construction and development of submillimeter/millimeter astronomical instrumentation. Specifically we have begun a program to measure the optical properties of the custom plastics used in 3D-printers as well as the printer accuracy and resolution to assess the feasibility of directly printing sub- /millimeter transmissive optics. We will also discuss low cost designs for cryogenic temperature measurement and control utilizing Arduino and Raspberry Pi.

The CCAT observatory is a 25-m class Gregorian telescope designed for submillimeter observations that will be deployed at Cerro Chajnantor (~5600 m) in the high Atacama Desert region of Chile. The Short Wavelength Camera (SWCam) for CCAT is an integral part of the observatory, enabling the study of star formation at high and low redshifts. SWCam will be a facility instrument, available at first light and operating in the telluric windows at wavelengths of 350, 450, and 850 μm. In order to trace the large curvature of the CCAT focal plane, and to suit the available instrument space, SWCam is divided into seven sub-cameras, each configured to a particular telluric window. A fully refractive optical design in each sub-camera will produce diffraction-limited images. The material of choice for the optical elements is silicon, due to its excellent transmission in the submillimeter and its high index of refraction, enabling thin lenses of a given power. The cryostat’s vacuum windows double as the sub-cameras’ field lenses and are ~30 cm in diameter. The other lenses are mounted at 4 K. The sub-cameras will share a single cryostat providing thermal intercepts at 80, 15, 4, 1 and 0.1 K, with cooling provided by pulse tube cryocoolers and a dilution refrigerator. The use of the intermediate temperature stage at 15 K minimizes the load at 4 K and reduces operating costs. We discuss our design requirements, specifications, key elements and expected performance of the optical, thermal and mechanical design for the short wavelength camera for CCAT.

An automated test system was developed to characterize detectors for the Kilopixel Array Pathfinder Project (KAPPa), a 16-pixel 2D integrated heterodyne focal plane array. Although primarily designed for KAPPa, the system can be used with other instruments to automate tests that might be tedious and time-consuming by hand. Mechanical components include an adjustable structure of aluminum t-slot framing that supports a rotating chopper. Driven by a stepper motor, the wheel alternates between blackbodies at room temperature and 77 K. The cold load consists of absorbing material submerged in liquid nitrogen in an open Styrofoam cooler. Python scripts control the mechanical system, interface with receiver components, and process data. Test system operation was verified by sweeping the local oscillator frequency with a Virginia Diodes room temperature receiver. The system was then integrated with the KAPPa receiver to allow complete and automated testing of all array pixels with minimal user intervention.

We report the development of the software-based polarization spectrometer‘ PolariS ’and early results from commissioning on the Nobeyama 45-m radio telescope. PolariS aims to detect the Zeeman effect of CCS line to measure ~ 100 μG magnetic fields in star-forming molecular cores. The PolariS consists of the K5/VSSP32 digitizer and a Linux-based PC with a GPU to process full-Stokes spectroscopy of 2 x 131072 ch for bandwidth of 4 or 8 MHz. We have verified performance of PolariS and succeeded to take full-stokes spectra of SiO masers. Since the code is open at GitHub everybody can utilize it.

Sideband-separating receivers are usually preferred in the presence of high atmospheric noise. However, one of the most important figures of merit for this kind of receiver, the sideband ratio, is still low and typically around 10 dB. This is because keeping low amplitude and phase imbalances over large RF and IF frequencies is extremely difficult. However, by introducing a digital back-end that mimics the performance of an IF-hybrid, such imbalances can be calibrated out. We have recently presented a digital sideband-separating receiver, working at the W band, that can achieve sideband ratios well above 35 dB. Here we extend this work by demonstrating that it can also be applied to receivers that incorporate a second down-conversion stage with the same performance.

Heterodyne focal plane arrays used in the terahertz (THz) regime currently require a discrete set of rigid coaxial cables for the transmission of individual intermediate frequency (IF) signals. Consequently, the size of an array is limited to ~10s of pixels due to limited physical space and the complexity of assembly. In order to achieve an array with ~1000 pixels or greater, new interconnections must be developed capable of carrying multiple IF signals on a single carrier which is flexible, robust to noise, and terminated with a high density RF connector. As an intermediate step to the development of a ~1000 pixel heterodyne focal plane array, the Kilopixel Array Pathfinder Project (KAPPa) has developed a 16 channel IF flex circuit. Initially, design simulations were performed to evaluate various means of high-frequency (1~10 GHz) signal transmission, including microstrip, stripline and coplanar waveguides. The method allowing for the closest signal spacing and greatest resistance to radio frequency interference (RFI) was determined to be stripline. Designs were considered where stripline transitioned to microstrip in order to terminate the signal. As microstrip transmission lines are sensitive to RFI, a design featuring just stripline was evaluated. In both the stripline-to-microstrip and stripline-only designs, a three-layer copper-coated polyimide substrate was used. Signal transitions were accomplished by a signal carrying “hot” via passing through a series of three conductive pads, similar to work by Leib et al. (2010). The transition design essentially mimics a coaxial line, where the radial distance between the pads and the ground plane is optimized in order to achieve desired impedances. In simulation, 50 Ohm impedances were achieved throughout, with crosstalk and return loss limited to -30dB. Terminations are made via an array of Corning Gilbert G3PO blind mate connectors, which are small enough to match the 6mm pixel pitch of the KAPPa focal plane unit. In addition, circuits with SMA terminations were designed to enable straightforward testing with a vector network analyzer (VNA). Initial designs use ½ oz. (18 microns thickness) copper conductors. In the KAPPa application, the copper conductor is still suitable for cryogenic applications because of the very small cross section presented by the copper conductor. The stripline design allows the interconnect to be clamped securely for heat sinking with a copper clamp at 10K and 60K. Heat load to the 4K stage is limited to 10 mW if the circuit is heat sunk at 10K 150mm from the 4K focal plane. Future designs could be implemented with phosphor bronze as the conductor to further limit heat load at the expense of added loss.

A central component of a sideband separating (2SB) receiver is the quadrature hybrid which splits the incoming radio frequency signal into two branches with a 90°-phase shift. Its fabrication, however, is one of the factors limiting the operational bandwidth and the maximum frequency at which a 2SB can be built. In this paper a 100%-photonic approach to produce this split is presented. In this way, wider operational bandwidth and a higher maximum operational frequency could be achieved. We also present the first experimental results of a proof-of-concept implementation at 55 MHz that studied the phase stability and controllability of this approach using a commercial 90-degree optical hybrid.

The prototype cartridges for ALMA Band-1 receivers have been developed, based on the key components developed in ALMA Band-1 consortium laboratories. The prototype cartridges for each receiver consist of two parts, cold cartridge assembly and warm cartridge assembly. The cold cartridge assembly (CCA) consists of horn antenna, orthomode transducer and a pair of 35-52 GHz cold low-noise amplifiers, the amplified signals of both polarizations are transmitted to warm cartridge assembly by long waveguide sections. In warm cartridge assembly (WCA), two major modules incorporated, down-converter assembly including warm low-noise amplifier, high-pass filter, mixer and 4-12 GHz IF amplifier, and local oscillator based on a 31-40 GHz YIG-tunes oscillator. The frequency range is based on the upper sideband scheme. Based on the measured performance of the key components, the expected noise performance of the receiver will be 26-33K.

The ALMA telescope will be composed of 66 high precision antennas; each antenna producing 8 times 2GHz bandwidth signals (4 pairs or orthogonal linear polarizations signals). Detecting the root cause of a loss of coherence issue between pairs of antennas can take valuable time which could be used for scientific purposes. This work presents an approach for quickly determining, in a systematic fashion, the source of this kind of issues. Faulty sub-system can be detected using the telescope calibration software and the granularity information. In a complex instrument such as the ALMA telescope, finding the cause of a loss of coherence issue can be a cumbersome task due to the several sub-systems involved on the signal processing (Frequency down-converter, analog and digital filters, instrumental delay), the interdependencies between sub-systems can make this task even harder. A method based on the information provided by the TelCal¹ sub-system (in specific the Delay Measurements) will be used to help identify either the faulty unit or the wrong configuration which is causing the loss of coherence issue. This method uses granularity information to help find the cause of the problem.

We present the optical and mechanical design of a 3mm band SIS receiver for the Gregorian focus of the Sardinia Radio Telescope (SRT). The receiver, was designed and built at IRAM and deployed on the IRAM for the Plateau de Bure Interferometer antennas until 2006. Following its decommissioning the receiver was purchased by the INAFAstronomical Observatory of Cagliari with the aim to adapt its optics for test of the performance of the new 64-m diameter Sardinia Radio Telescope (SRT) in the 3 mm band (84 – 116 GHz). The instrument will be installed in the rotating turret inside of the Gregorian focal room of SRT. The dimensions of the focal room, the horn position in the lower side of the cryostat and the vessel for the liquid helium impose very hard constraints to the optical and mechanical mounting structure of the receiver inside the cabin. We present the receiver configuration and how we plan to install it on SRT.

The ALMA telescope is composed of 66 high precision antennas, each antenna having 8 high bandwidth digitizers (4Gsamples/Second). It is a critical task to determine the well functioning of those digitizers prior to starting a round of observations. Since observation time is a valuable resource, it is germane that a tool be developed which can provide a quick and reliable answer regarding the digitizer status. Currently the digitizer output statistics are measured by using comparators and counters. This method introduced uncertainties due to the low amount of integration, in addition to going through all the possible states for all available digitizer time which all resulted in the antennas taking a considerable amount of time. In order to avoid the aforementioned described problems, a new method based on correlator resources is hereby presented.

We propose the Allan Variance method to identify spurious signals with sensitive detectability. With this method, detection level of -56 dB with respect to the system noise can be achieved within the integration time less than 10 min. Detected spurious signals can be mitigated by masking these channels before spectral bunching to required spectral resolution. We will present the principle of the method and the performance taken through the ALMA system verification activity. This method can be applied for universal single-dish spectroscopy.

Radio astronomical observations are ordinarily aimed at reaching a specific scientific goal. Radio telescopes are equipped with a certain number of receivers and back-ends, and the choice of the most suitable receiver/back-end combination in order to best match the scientific application of interest is up to the astronomer. However, the opportunity to process the incoming signal, simultaneously, with different back-ends, thus providing different observational 'points of view', may indeed provide additional scientific results. In this paper, we describe a system, developed for the Sardinia Radio Telescope (SRT), which allows the observer to take profit of such a capability.

We present the results of a development activity for cryogenic Low Noise Amplifiers based on HEMT technology for ground based and space-borne application. We have developed and realized two LNA design in W band, based on m-HEMT technology. MMIC chips have been manufactured by European laboratories and companies and assembled in test modules by our team. We compare performances with other technologies and manufacturers. LNA RF properties (noise figures, S-parameters) have been measured at room and cryogenic temperature and test results are reported in this paper. Performance are compared with those of state-of-the-art devices, as available in the literature. Strengths and improvements of this project are also discussed.

We investigate a new concept, where a single superconductor-insulator-superconductor (SIS) based mixer chip is switched between two RF frequency bands. A single broadband antenna is used to couple the RF/LO signal to two SIS mixers via a power splitter and two superconducting on/off switches, forming a switching circuit. The planar on/off switches comprise a superconducting microstrip bridging two transmission lines used to alternate the RF/LO signal between the two branches of the power splitter circuit by switching the impedance of the microstrip from the superconducting to normal state, and vice versa. An important application of this dual-band design is to enable combination of adjacent observing astronomical windows into a single receiver cartridge, freeing valuable space in the receiver cabin.

Wide field cryogenic optics and millimeter-wave Microwave Kinetic Inductance Detector (MKID) cameras with Si lens array have been developed. MKID is a Cooper-pair breaking photon detector and consists of supercon- ducting resonators which enable microwave (~GHz) frequency multiplexing. Antenna-coupled Aluminum CPW resonators are put in a line on a Si substrate to be read by a pair of coaxial cables. A 220 GHz - 600 pixels MKID camera with anti-reflection (AR) coated Si lens has been demonstrated in an 0.1 K cryostat. A compact cryogenic system with high refractive index materials has been developed for the MKID camera.

The impacts of Cosmic Rays on the detectors are a key problem for space-based missions. We are studying the effects of such interactions on arrays of Kinetic Inductance Detectors (KID), in order to adapt this technology for use on board of satellites. Before proposing a new technology such as the Kinetic Inductance Detectors for a space-based mission, the problem of the Cosmic Rays that hit the detectors during in-flight operation has to be studied in detail. We present here several tests carried out with KID exposed to radioactive sources, which we use to reproduce the physical interactions induced by primary Cosmic Rays, and we report the results obtained adopting different solutions in terms of substrate materials and array geometries. We conclude by outlining the main guidelines to follow for fabricating KID for spacebased applications.

Kinetic inductance detectors (KIDs) are a promising technology for low-noise, highly-multiplexible mm- and submm-wave detection. KIDs have a number of advantages over other detector technologies, which make them an appealing option in the cosmic microwave background B-mode anisotropy search, including passive frequency domain multiplexing and relatively simple fabrication, but have suffered from challenges associated with noise control. Here we describe design and fabrication of a 20-pixel prototype array of lumped element molybdenum KIDs. We show Q, frequency and temperature measurements from the array under dark conditions. We also present evidence for a double superconducting gap in molybdenum.

We have been developing a lens-integrated superconducting camera for millimeter and submillimeter astronomy. High-purity silicon (Si) is suitable for the lens array of the Microwave Kinetic Inductance Detector (MKID) camera due to the high refractive index and the low dielectric loss at low temperature. The camera is antenna-coupled Al coplanar waveguides on a Si substrate. Thus the lens and the device are made of the same material. We report a fabrication method of 721 pixel Si lens array with anti-reflection coating. The Si lens array was fabricated with an ultra-precision cutting machine. It uses TiAlN coated carbide end mills attached with a high-speed spindle. The shape accuracy was less than 50 μm peak-to-valley and the surface roughness was Ra 1.8 μm. The mixed epoxy was used as anti-reflection coating to adjust the refractive index. It was shaved to make the thickness of 185 μm for 220 GHz. Narrow grooves were made between the lenses to prevent cracking due to different thermal expansion coefficients of Si and the epoxy. The surface roughness of the anti-reflection coating was Ra 2.4 ~ 4.2 μm.

We designed wide FoV (1 degree) Nasmyth optics which transformed the f/6 Nasmyth focus to f/1 at a 850GHz superconducting camera for a planning 10-m Ritchey-Chrétien telescope. This optical system consists of reflecting mirrors at room temperature and a refractive lens at 4K. It enables us to carry out wide FoV imaging observations at the diffraction limit (Strehl ratio < 0.89) with a more than 100,000 pixel camera equipped in a 10-m telescope. The size of this system is reasonably compact (whole size:1.6 mx3.3 mx2.6 m, cryogenic part:0.7 mx0.7 mx1.0 m). The cryogenic part of this system such as vacuum window, cryogenic lens and IR block filters can be made with existing technologies at reasonable cost. The optical system can extend to the millimeter wave and the terahertz domain.

In this paper we describe the optical modelling of astronomical telescopes that exploit bolometric detectors fed by multimoded horn antennas. In cases where the horn shape is profiled rather than being a simple cone, we determine the beam at the horn aperture using an electromagnetic mode-matching technique. Bolometers, usually placed in an integrating cavity, can excite many hybrid modes in a corrugated horn; we usually assume they excite all modes equally. If the waveguide section feeding the horn is oversized these modes can propagate independently, thereby increasing the throughput of the system. We use an SVD analysis on the matrix that describes the scattering between waveguide (TE/TM) modes to recover the independent orthogonal fields (hybrid modes) and then propagate these to the sky independently where they are added in quadrature. Beam patterns at many frequencies across the band are then added with a weighting appropriate to the source spectrum. Here we describe simulations carried out on the highest-frequency (857-GHz) channel of the Planck HFI instrument. We concentrate in particular on the use of multimode feedhorns and consider the effects of possible manufacturing tolerances on the beam on the sky. We also investigate the feasibility of modelling far-out sidelobes across a wide band for electrically large structures and bolometers fed by multi-mode feedhorns. Our optical simulations are carried out using the industry-standard GRASP software package.

We present the development and characterisation of a high frequency (500 – 750 GHz) corrugated horn based on stacked rings. A previous horn design, based on a Winston profile, has been adapted for the purpose of this manufacturing process without noticeable RF degradation. A subset of experimental results obtained using a vector network analyser are presented and compared to the predicted performance. These first results demonstrate that this technology is suitable for most commercial applications and also astronomical receivers in need of horn arrays at high frequencies.

ECCOSORB^TM CR/MF is a widely used absorber at radio and millimeter wavelengths. It is used both at room and at cryogenic temperature to realize loads and calibrators both for laboratory and for space-borne instruments. Data on its RF properties are available from the data sheet at room temperature. But it is also widely used outside the design wavelength range and at cryogenic temperature, where specific measurement of electromagnetic and thermal properties are needed. Scarce information is available in the literature and inconsistencies are frequent. We report here new RF data in Ka and W-band at room temperature obtained with waveguide measurements with different setups.

Low-loss lenses are required for submillimeter astronomical applications, such as instrumentation for CCAT, a 25 m diameter telescope to be built at an elevation of 18,400 ft in Chile. Silicon is a leading candidate for dielectric lenses due to its low transmission loss and high index of refraction; however, the latter can lead to large reflection losses. Additionally, large diameter lenses (up to 40 cm), with substantial curvature present a challenge for fabrication of antireflection coatings. Three anti-reflection coatings are considered: a deposited dielectric coating of Parylene C, fine mesh structures cut with a dicing saw, and thin etched silicon layers (fabricated with deep reactive ion etching) for bonding to lenses. Modeling, laboratory measurements, and practicalities of fabrication for the three coatings are presented and compared. Measurements of the Parylene C anti-reflection coating were found to be consistent with previous studies and can be expected to result in a 6% transmission loss for each interface from 0.787 to 0.908 THz. The thin etched silicon layers and fine mesh structure anti-reflection coatings were designed and fabricated on test silicon wafers and found to have reflection losses less than 1% at each interface from 0.787 to 0.908 THz. The thin etched silicon layers are our preferred method because of high transmission efficiency while having an intrinsically faster fabrication time than fine structures cut with dicing saws, though much work remains to adapt the etched approach to curved surfaces and optics < 4" in diameter unlike the diced coatings.

Here we describe the principles behind the design, construction, and implementation of a vector near-field beam scanner for the antennas of the Submillimeter Array. The Submillimeter Array (SMA) is a radio interferometer array operating at frequencies ranging from 200 { 700 GHz at the summit of Maunakea in Hawaii. A set of 4 receivers cover the key atmospheric windows over which the SMA operates. Each receiver insert is equipped with an ambient optical insert, which is pre-aligned in the lab prior to installation at the summit. However, as a result of receiver upgrades and problems, some receiver inserts may no longer be matched to the original optics inserts. Since the SMA is used extensively in dual-receiver observations, such beam mis-alignments lead to a relative pointing error between a pair of receivers during the observation. In order to address this issue, we have designed a near-field beam scanner which can be used to map out the receiver beam of each antenna. The setup employs the existing radio references available in each antenna for the vector beam measurement. We have successfully used this scanner to improve the on-sky co-alignment of receiver beams. In this presentation, we will describe the system and operational aspect of this in-situ radio frequency alignment technique.

The QUIJOTE TGI instrument is currently being assembled and tested at the IAC in Spain. The TGI is a 31 pixel 26-36 GHz polarimeter array designed to be mounted at the focus of the second QUIJOTE telescope. This follows a first telescope and multi-frequency instrument that have now been observing almost 2 years. The polarimeter design is based on the QUIET polarimeter scheme but with the addition of an extra 90º phase switch which allows for quasiinstantaneous complete QUI measurements through each detector. The advantage of this solution is a reduction in the systematics associated with differencing two independent radiometer channels. The polarimeters are split into a cold front end and a warm back end. The back end is a highly integrated design by the engineers at DICOM. It is also sufficiently modular for testing purposes. In this presentation the high quality wide band components used in the optical design (also designed in DICOM) are presented as well as the novel cryogenic modular design. Each polarimeter chain is accessible individually and can be removed from the cryostat and replaced without having to move the remaining pixels. The optical components work over the complete Ka band showing excellent performance. Results from the sub unit measurements are presented and also a description of the novel calibration technique that allows for bandpass measurement and polar alignment. Terrestrial Calibration for this instrument is very important and will be carried out at three points in the commissioning phase: in the laboratory, at the telescope site and finally a reduced set of calibrations will be carried out on the telescope before measurements of extraterrestrial sources begin. The telescope pointing model is known to be more precise than the expected calibration precision so no further significant error will be added through the telescope optics. The integrated back-end components are presented showing the overall arrangement for mounting on the cryostat. Many of the microwave circuits are in-house designs with performances that go beyond commercially available products.

During ArTeMiS observations at the APEX telescope (Chajnantor, Chile), 5760 bolometric pixels from 20 arrays at 300mK, corresponding to 3 submillimeter focal planes at 450μm, 350μm and 200μm, have to be read out simultaneously at 40Hz. The read out system, made of electronics and software, is the full chain from the cryostat to the telescope. The readout electronics consists of cryogenic buffers at 4K (NABU), based on CMOS technology, and of warm electronic acquisition systems called BOLERO. The bolometric signal given by each pixel has to be amplified, sampled, converted, time stamped and formatted in data packets by the BOLERO electronics. The time stamping is obtained by the decoding of an IRIG-B signal given by APEX and is key to ensure the synchronization of the data with the telescope. Specifically developed for ArTeMiS, BOLERO is an assembly of analogue and digital FPGA boards connected directly on the top of the cryostat. Two detectors arrays (18*16 pixels), one NABU and one BOLERO interconnected by ribbon cables constitute the unit of the electronic architecture of ArTeMiS. In total, the 20 detectors for the tree focal planes are read by 10 BOLEROs. The software is working on a Linux operating system, it runs on 2 back-end computers (called BEAR) which are small and robust PCs with solid state disks. They gather the 10 BOLEROs data fluxes, and reconstruct the focal planes images. When the telescope scans the sky, the acquisitions are triggered thanks to a specific network protocol. This interface with APEX enables to synchronize the acquisition with the observations on sky: the time stamped data packets are sent during the scans to the APEX software that builds the observation FITS files. A graphical user interface enables the setting of the camera and the real time display of the focal plane images, which is essential in laboratory and commissioning phases. The software is a set of C++, Labview and Python, the qualities of which are respectively used for rapidity, powerful graphic interfacing and scripting. The commands to the camera can be sequenced in Python scripts. The paper describes the whole electronic and software readout chain designed to fulfill the specificities of ArTeMiS and its performances. The specific options used are explained, for example, the limited room in the Cassegrain cabin of APEX has led us to a quite compact design. This system was successfully used in summer 2013 for the commissioning and the first scientific observations with a preliminary set of 4 detectors at 350μm.

POLARBEAR-2 is a next-generation receiver for precision measurements of polarization of the cosmic microwave background, scheduled to deploy in 2015. It will feature a large focal plane, cooled to 250 milliKelvin, with 7,588 polarization-sensitive antenna-coupled transition edge sensor bolometers, read-out with frequency domain multiplexing with 32 bolometers on a single SQUID amplifier. We will present results from testing and characterization of new readout components, integrating these components into a scaled-down readout system for validation of the design and technology.

We present the preliminary results of the design and test activities for a DC cryogenic low noise amplifier for the SAFARI imaging spectrometer, planned to be onboard the SPICA mission, necessary not only to drive, as usual, the voltage signal produced by the SQuID but also to boost such signals over about 7 meter of path towards the warm feedback electronics. This development has been done in the framework of the mission preparation studies, within the European Consortium for the development of the SAFARI instrument. The actual configuration of the SAFARI focal plane assembly (FPA), indeed, foresees a long distance to the warm back end electronics. It is therefore mandatory to boost the faint electric signal coming from the SQuID device by keeping under control both power dissipation and noise: this is the main role of the designed Cryogenic Low Noise Amplifier (LNA). Working at 136K, it has a differential input gain-stage, and a differential balanced voltage buffer output stage, running at few mW target overall power. At present the design is based on the use of Heterojunction Si:Ge transistors, the required bandwidth is DC-4MHz and the required noise lower than 1 nV/rtHz.

Radio Frequency Interferences (RFI) represents one of the major issues especially in single-dish low frequency radioastronomic observations. Several solutions have been investigated to face the problem. Among them a wide-band digital spectrometer is used together to a RFI monitoring station placed close to the radio-telescope and eventually supported by a RFI mobile laboratory. In this paper a system combining such as approaches is described. The first one is a wide-band FFT spectrometer designed for RFI purposes, then the second consists of a station dedicated to RF environment monitoring. Advantages and drawbacks of this hybrid approach will be shown.

POLARBEAR-2 (PB-2) is a cosmic microwave background (CMB) polarization experiment for B-mode detection. The PB-2 receiver has a large focal plane and aperture that consists of 7588 transition edge sensor (TES) bolometers at 250 mK. The receiver consists of the optical cryostat housing reimaging lenses and infrared filters, and the detector cryostat housing TES bolometers. The large focal plane places substantial requirements on the thermal design of the optical elements at the 4K, 50K, and 300K stages. Infrared filters and lenses inside the optical cryostat are made of alumina for this purpose. We measure basic properties of alumina, such as the index of refraction, loss tangent and thermal conductivity. All results meet our requirements. We also optically characterize filters and lenses made of alumina. Finally, we perform a cooling test of the entire optical cryostat. All measured temperature values satisfy our requirements. In particular, the temperature rise between the center and edge of the alumina infrared filter at 50 K is only 2:0 ± 1:4 K. Based on the measurements, we estimate the incident power to each thermal stage.

The inflationary paradigm of the early universe predicts a stochastic background of gravitational waves which would generate a B-mode polarization pattern in the cosmic microwave background (CMB) at degree angular scales. Precise measurement of B-modes is one of the most compelling observational goals in modern cosmology. Since 2011, the Keck Array has deployed over 2500 transition edge sensor (TES) bolometer detectors at 100 and 150 GHz to the South Pole in pursuit of degree-scale B-modes, and Bicep3 will follow in 2015 with 2500 more at 100 GHz. Characterizing the spectral response of these detectors is important for controlling systematic effects that could lead to leakage from the temperature to polarization signal, and for understanding potential coupling to atmospheric and astrophysical emission lines. We present complete spectral characterization of the Keck Array detectors, made with a Martin-Puplett Fourier Transform Spectrometer at the South Pole, and preliminary spectra of Bicep3 detectors taken in lab. We show band centers and effective bandwidths for both Keck Array bands, and use models of the atmosphere at the South Pole to cross check our absolute calibration. Our procedure for obtaining interferograms in the field with automated 4-axis coupling to the focal plane represents an important step towards efficient and complete spectral characterization of next-generation instruments more than 10000 detectors.

We have demonstrated a kilopixel, filled, infrared bolometer array for the balloon-borne Primordial Inflation Polarization Explorer (PIPER). The array consists of three individual components assembled into a single working unit: 1) a transition-edge-sensor bolometer array with background-limited sensitivity, 2) a quarter–wavelength backshort grid, and 3) an integrated Superconducting Quantum Interference Device (SQUID) multiplexer (MUX) readout. The detector array is a filled, square–grid of suspended, one-micron thick silicon bolometers with superconducting sensors. The Backshort–Under–Grid (BUG) is a separately fabricated component serving as a backshort to each pixel in the array. The backshorts are positioned in the cavities created behind each detector by the back–etched well. The spacing of the backshort beneath the detector grid can be set from ~30-300_microns by independently adjusting process parameters during fabrication. Kilopixel arrays are directly indium–bump–bonded to a 32x40 SQUID multiplexer circuit. The array architecture is suitable for a wide range of wavelengths and applications. Detector design specific to the PIPER instrument, fabrication overview, and assembly technologies will be discussed.

Here we present the methodology and initial results for a new near-field antenna radiation measurement system for submillimeter receivers. The system is based on a 4-port vector network analyzer with two synthesized sources. This method improves on similar systems employing this technique with the use of the network analyzer, which reduces the cost and complexity of the system. Furthermore, a single set of test equipment can analyze multiple receivers with different central frequencies; the frequency range of the system is limited by the output range of the network analyzer and/or the power output of the source signal. The amplitude and phase stability of the system in one configuration at 350 GHz was measured and found to be accurate enough to permit near field antenna measurements. The proper characterization of phase drifts across multiple test configurations demonstrates system reliability. These initial results will determine parameters necessary for implementing a near-field radiation pattern measurement of a Schottky diode receiver operating between 340-360 GHz.