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 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) . 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. , 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 TiNx and first measurements on a test sample.
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 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 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.
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.
A digital frequency multiplexing electronics building block has been developed for the NIKA (New IRAM KID
Arrays) experience. It allows the real time monitoring of microwave kinetic inductance detectors (MKIDs)
arrays used for mm-wave astronomy. This electronics can monitor simultaneously 400 pixels over a 500MHz
bandwidth and requires only two coaxial cables for instrumenting such a large array. The chosen solution and
the performance achieved are presented in this paper.
We present latest developments of the millimetric Stationary Waves Integrated Fourier Transform Spectrometer
(SWIFTS) that uses the Kinetic Inductance Detectors (KID) technology. SWIFTs are on-chip autocorrelator
spectrometers where the incoming signal forms an interferogram by reflection in a short-circuited coplanar wave-guide.
By collecting electromagnetic (EM) energy along the guide, one can retrieve this interference pattern. A subsequent offline
Fourier transform gives spectral information with a moderate resolution (~500-1000). SWIFTS concept has already
been proven to work in the optical and microwave (<20 GHz) bands. It will be useful in any application where integrated
and broadband spectral analysis is needed, as an example it will be a practical alternative to Martin-Pupplet
interferometer. In practice, fabrication of such a device is very challenging mostly because the set of detectors has to
collect energy without destroying the interference pattern. As a consequence, design of the coupling parts is a crucial
problem that has to be tackled with the help of EM simulation tools. We present here the SWIFTS principle of operation,
details of fabrication, and the latest simulations results.
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.
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.
Bolometers cooled to very low temperature are currently the most sensitive detectors for low spectral resolution
detection of millimetre and sub-millimetre wavelengths. The best performances of the state-of-the-art bolometers allow
to reach sensitivities below the photon noise of the Cosmic Microwave Background for example. Since 2003, a french
R&D effort called DCMB ("Developpement Concerte de Matrices de Bolometres") has been organised between different
laboratories to develop large bolometers arrays for astrophysics observations. Funded by CNES and CNRS, it is intended
to get a coherent set of competences and equipments to develop very cold bolometers arrays by microfabrication. Two
parallel developments have been made in this collaboration based on the NbSi alloy either semi-conductive or
superconducting depending on the proportion of Nb. Multiplexing schemes have been developed and demonstrated for
these two options. I will present the latest developments made in the DCMB collaboration and future prospects.
We present the design and the present development status of a 204 pixels mm-wave bolometric camera compatible with
the 30 meter IRAM telescope at Pico Veleta. Sequential and non-sequential ray-tracing and physical optics simulations
have been performed with ZEMAX, taking into account the IRAM mirrors and the telecentric camera. The focal plane is
made by an array of antenna-coupled NbSi microbolometers, described in brief. We present the cryostat design, and then
more in details the optics and the baffling system. We conclude with a brief discussion on the future perspectives toward
the multi-thousands pixels bolometric mm-wave camera at IRAM.
We describe the design and construction of a novel optical ring-polarimeter (RINGO) for the Liverpool Telescope. The instrument is designed for rapid (< 5 minutes) followup observations of Gamma Ray Bursts in order to measure the early time polarization and its evolution for the first time. Sensitivity calculations and data reduction procedures are described, and the results of on-sky commissioning presented. The instrument is now on the telescope and in routine use during GRB followup.
Fast ground based simultaneous optical-near infrared observation of gamma-ray bursts (GRBs) is a mandatory priority to understand the physical mechanisms at work in these objects. The REM (Rapid Eye Mount) telescope, recently installed at La Silla (ESO, Chile), is an example of a new generation of small robotic telescopes having the capability to allow simultaneous optical and near infrared photometry and low resolution spectroscopy. The REM Optical Slitless Spectrograph (ROSS) is the optical instrument mounted on REM. ROSS has been attached, in one of the two Nasmyth foci, orthogonally to the optical axis and receives the optical light deflected by a beam splitter (dichroic), which leaves the infrared beam to continue along the optical axis where the infrared camera (REM-IR) is installed. Low resolution optical spectroscopy is obtained using an Amici prism mounted on the same filter wheel where are also mounted the broad-band V, R, I photometric filters. The detector head is a commercial camera hosting a Marconi 1024×1024 CCD chip.
SD2000 is a new photon counting MCP based detector. It consists of a single MCP, coated with a suitable photocathode, closely coupled to a Silicon Drift Detector (SDD). The electron clouds generated by the MCP channels are accelerated by a strong electric field applied and proximity focussed on the SDD, that works as a position sensitive read-out detector. The SDD, developed by the INFN laboratories in Trieste, is a butterfly Silicon Drift Detector with no metal deposition on its cathodes. The absence of metallization in the sensitive zone of the chamber allows the electron clouds to penetrate uniformly into the active region of the detector and to be revealed. A suitable front-end amplifier, that works as a charge preamplifier and a bipolar shaper, has been developed starting from SPICE simulations and tested. A proto-type of the detector has been realized and tested and the first results have been achieved and compared with the expected best performances of the detector.
A light photon-counting scientific payload, named AURORA, has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission (channel Notte) and the Aurora (Alba). AURORA is mapping, with the Notte channel, the night-side photon background in the 300-400 nm spectral range, together with a particular 2+ nitrogen line ((lambda) = 337nm). These measurements are required in the framework of the Extreme Universe Space Observatory (EUSO) experiment, approved by the European Space Agency (ESA) for the phase A and to be flown on the International Space Station (ISS) in 2009. The Alba channel studies the Aurora emissions in four different spectral bands centered on: 367nm, 391nm, 535nm, 560nm (OI). The instrument has been integrated on the MEGSAT-1 satellite and launched, on the September, 26th 2000, from the Baikonur cosmodrome. The nearly circular Low Earth Orbit (LEO), with inclination of 64.56 degrees, fully includes the ISS ground track envelope. The satellite overall mass is about 60 kg. An overview of the techniques adopted, including detectors, front-end electronics, Central Processor Unit (CPU), is given in this paper, together with a brief report on the mission status and plans.
A new photon counting detector for UV Astronomy is presented. The SD2000 detector consists of a single MCP, coated with a suitable photocathode, closely coupled to a Silicon Drift Detector (SDD). A good spatial resolution, of the order of 20 micrometer in both directions, can be achieved with a relatively small number of readout channels (10 divided by 100). The maximum allowable rate, proportional to the drift length, is about 105 Hz for a 20 mm length focal plane. A new type of SDD, without metal deposition on the cathodes, has been developed and tested for this particular application. A single MCP has been coupled also to a metal anode and a silicon diode in order to characterize it and study the interaction between the incoming (low-energy) electron cloud and a silicon p-n junction similar to those present in the drift chamber.