SPACEKIDS, a European Union FP-7 project, has recently been completed. It has focused on developing kinetic
inductance detector (KID) arrays and demonstrating their suitability for space applications at far infrared and
submillimetre wavelengths. KID arrays have been developed for both low-background (typical of astrophysical
applications) and high-background (typical of Earth-observation applications), based on performance specifications
derived from the science requirements of representative potential future missions. KID pixel and array designs have
been developed, together with readout electronics necessary to read out large numbers of pixels. Two laboratory
demonstrator systems have been built and used for comprehensive evaluation of large-format array characteristics and
performance in environments representative of both astronomy and Earth observing applications. We present an
overview of the SPACEKIDS project and a summary of its main results and conclusions.
Kinetic Inductance Detectors (KID) are now routinely used in ground-based telescopes. Large arrays, deployed in
formats up to kilopixels, exhibit state-of-the-art performance at millimeter (e.g. 120-300 GHz, NIKA and NIKA2 on the
IRAM 30-meters) and sub-millimeter (e.g. 350-850 GHz AMKID on APEX) wavelengths. In view of future utilizations
above the atmosphere, we have studied in detail the interaction of ionizing particles with LEKID (Lumped Element KID)
arrays. We have constructed a dedicated cryogenic setup that allows to reproduce the typical observing conditions of a
space-borne observatory. We will report the details and conclusions from a number of measurements. We give a brief
description of our short term project, consisting in flying LEKID on a stratospheric balloon named B-SIDE.
Keywords: cryogenics detectors, millimeter-wave, superconducting resonators.
We report on the development of scalable prototype microwave kinetic inductance detector (MKID) arrays tai- lored for future multi-kilo-pixel experiments that are designed to simultaneously characterize the polarization properties of both the cosmic microwave background (CMB) and Galactic dust emission. These modular arrays are composed of horn-coupled, polarization-sensitive MKIDs, and each pixel has four detectors: two polariza- tions in two spectral bands between 125 and 280 GHz. A horn is used to feed each array element, and a planar orthomode transducer, composed of two waveguide probe pairs, separates the incoming light into two linear po- larizations. Diplexers composed of resonant-stub band-pass filters separate the radiation into 125 to 170 GHz and 190 to 280 GHz pass bands. The millimeter-wave power is ultimately coupled to a hybrid co-planar waveguide microwave kinetic inductance detector using a novel, broadband circuit developed by our collaboration. Elec- tromagnetic simulations show the expected absorption efficiency of the detector is approximately 90%. Array fabrication will begin in the summer of 2016.
We discuss the design considerations and initial measurements from arrays of dual-polarization, lumped-element
kinetic inductance detectors (LEKIDs) nominally designed for cosmic microwave background (CMB) studies. The
detectors are horn-coupled, and each array element contains two single-polarization LEKIDs, which are made
from thin-film aluminum and optimized for a single spectral band centered on 150 GHz. We are developing two
array architectures, one based on 160 micron thick silicon wafers and the other based on silicon-on-insulator (SOI)
wafers with a 30 micron thick device layer. The 20-element test arrays (40 LEKIDs) are characterized with both
a linearly-polarized electronic millimeter wave source and a thermal source. We present initial measurements
including the noise spectra, noise-equivalent temperature, and responsivity. We discuss future testing and further
design optimizations to be implemented.
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.
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.
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.
The Neel Iram Kids Array (NIKA) is a prototype instrument devoted to millimetric astronomy that has been
designed to be mounted at the focal plane of the IRAM 30m telescope at Pico Veleta (Spain). After the runs
of 2009 and 2010, we carried a third technical run in October 2011. In its latest configuration, the instrument
consists of a dual-band camera, with bands centered at 150 GHz and 220 GHz, each of them equipped with
116 pixels based on Lumped Element Kinetic Inductance Detectors. During the third run we tested many
improvements that will play a crucial role in the development of the final, kilopixel sized camera. In particular,
a new geometry based on a Hilbert curve has been adopted for the absorbing area of the LEKIDs, that makes
the detectors dual-polarization sensitive. Furthermore, a different acquisition strategy has been adopted, which
has allowed us to increase the photometric accuracy of the measurements, a fundamental step in order to get
scientifically significant data. In this paper we describe the main characteristics of the 2011 NIKA instrument
and outline some of its key features, discusse the results we obtained and give a brief outlook on the future NIKA
camera which will be installed permanently on site.
SuperSpec is an ultra-compact spectrometer-on-a-chip for millimeter and submillimeter wavelength astronomy. Its very small size, wide spectral bandwidth, and highly multiplexed readout will enable construction of powerful multibeam spectrometers for high-redshift observations. The spectrometer consists of a horn-coupled microstrip feedline, a bank of narrow-band superconducting resonator filters that provide spectral selectivity, and kinetic inductance detectors (KIDs) that detect the power admitted by each filter resonator. The design is realized using thin-film lithographic structures on a silicon wafer. The mm-wave microstrip feedline and spectral filters of the first prototype are designed to operate in the band from 195-310 GHz and are fabricated from niobium with at Tc of 9.2K. The KIDs are designed to operate at hundreds of MHz and are fabricated from titanium nitride with a Tc of ~ 2 K. Radiation incident on the horn travels along the mm-wave microstrip, passes through the frequency-selective filter, and is finally absorbed by the corresponding KID where it causes a measurable shift in the resonant frequency. In this proceedings, we present the design of the KIDs employed in SuperSpec and the results of initial laboratory testing of a prototype device. We will also brie describe the ongoing development of a demonstration instrument that will consist of two 500-channel, R=700 spectrometers, one operating in the 1-mm atmospheric window and the other covering the 650 and 850 micron bands.
SuperSpec is a pathfinder for future lithographic spectrometer cameras, which promise to energize extra-galactic astrophysics at (sub)millimeter wavelengths: delivering 200–500 kms-1 spectral velocity resolution over an octave bandwidth for every pixel in a telescope’s field of view. We present circuit simulations that prove the concept, which enables complete millimeter-band spectrometer devices in just a few square-millimeter footprint. We evaluate both single-stage and two-stage channelizing filter designs, which separate channels into an array of broad-band detectors, such as bolometers or kinetic inductance detector (KID) devices. We discuss to what degree losses (by radiation or by absorption in the dielectric) and fabrication tolerances affect the resolution or performance of such devices, and what steps we can take to mitigate the degradation. Such design studies help us formulate critical requirements on the materials and fabrication process, and help understand what practical limits currently exist to the capabilities these devices can deliver today or over the next few years.
SuperSpec is an innovative, fully planar, compact spectrograph for mm/sub-mm astronomy. SuperSpec is based on a superconducting filter-bank consisting of a series of planar half-wavelength filters to divide up the incoming, broadband radiation. The power in each filter is then coupled into titanium nitride lumped element kinetic inductance detectors, facilitating the read out of a large number of filter elements. We will present electromagnetic simulations of the different components that will make up an R = 700 prototype instrument. Based on these simulations, we discuss optimisation of the coupling between the antenna, transmission line, filters and detectors.
The Lumped Element Kinetic Inductance Detector (LEKID) was first proposed in 2007 as a solution for using
kinetic inductance type detectors for sub-mm astronomy (450 - 200μm). Since then the LEKID has been
demonstrated to have applications over a much wider range of wavelength. Examples of this have been 200μm
detection of a cold blackbody and successful testing of a demonstration array operating at 2mm on the IRAM
telescope in October 2009. Due to the combination of absorber and detector in a single element, the LEKID is
an extremely simple detector to fabricate requiring only one deposition and etch step to produce an array of up
to 1000 pixels multiplexed onto a single feedline. The LEKID is also a very compact detector making it ideal
for producing arrays with high filling factors. The suitability of the LEKID for use in large arrays has prompted
a return visit to the IRAM telescope with a dual band instrument in 2010. This presentation will review the
progress to date of the LEKIDs development and outline design considerations for producing LEKIDs for future
FIR astronomical instruments such as SPICA. Also reviewed will be possible applications for the LEKID outside
sub-mm and mm astronomy.
Lumped-element kinetic inductance detectors (LEKIDs) have recently shown considerable promise as direct-absorption
mm-wavelength detectors for astronomical applications. One major research thrust within the Néel Iram Kids Array (NIKA)
collaboration has been to investigate the suitability of these detectors for deployment at the 30-meter IRAM telescope located
on Pico Veleta in Spain.
Compared to microwave kinetic inductance detectors (MKID), using quarter wavelength resonators, the resonant circuit of
a LEKID consists of a discrete inductance and capacitance coupled to a feedline. A high and constant current density
distribution in the inductive part of these resonators makes them very sensitive. Due to only one metal layer on a silicon
substrate, the fabrication is relatively easy.
In order to optimize the LEKIDs for this application, we have recently probed a wide variety of individual resonator and
array parameters through simulation and physical testing. This included determining the optimal feed-line coupling, pixel
geometry, resonator distribution within an array (in order to minimize pixel cross-talk), and resonator frequency spacing.
Based on these results, a 32-pixel Aluminum array was fabricated and tested in a dilution fridge with optical access, yielding
an average optical NEP of ~7.2 x 10-16 W/Hz^1/2. In October 2009 a first prototype of LEKIDs has been tested at the IRAM
30 m telescope and first astronomical results have been achieved.
We describe a new type of FIR detector based on lumped element superconducting resonators (LEKIDs). These
devices can act as distributed FIR radiation absorbers without the need for an additional coupling structure.
In addition, these devices can be integrated into a compact filled array geometry with high filling factor. We
describe the optimization of lumped element resonators for high coupling efficiency to incoming radiation in the
wavelength region from 200μm - 450μm, measurements of electrical and optical properties of these devices and
the design of a prototype array using these detectors.
Kinetic inductance detectors (KIDs) provide an attractive solution to the production of large detector arrays for use in ground and space based 200μm astronomy. KIDs work by measuring the change in quasi-particle density upon photon absorption in a high Q superconducting resonator. A change in quasi-particle density is measured by a shift in phase of a microwave probe signal of frequency equal to that of the resonant frequency of the KID. Such detectors have a fundamental noise limit owing to the quasi-particle recombination rate, which, in a KID fabricated from a high quality Niobium film can give sensitivities of 10-18W√Hz at 1K. Constructing KIDs of varying resonant frequencies coupled to a single transmission line provides a multiplexed detector array with simple low temperature electronics. Here we discuss the theoretical requirements for both ground and space based 200μm cameras with various radiation coupling schemes for this wavelength range using distributed and lumped element high Q resonators.