COSMO (COSmic Monopole Observer) is an experiment aimed at the searching for spectral distortions in the CMB (Cosmic Microwave Background) between 120 and 300 GHz. COSMO will be operated from Concordia Station on the Antarctic plateau. The experiment is based on a cryogenic Martin-Puplett interferometer whose superconductive detectors are KIDs (Kinetic Inductance Detectors). The interferometer produces interferograms proportional to the difference between the sky and an internal reference black body. The sky signal has a fast modulation to compensate for the atmospheric fluctuations. A key requirement of the readout is an ultra-fast rate to track the signal modulation and also for detector diagnostic. The readout architecture is based on an IQ transceiver generating a comb of test tones tuned to each detector. We developed a modular readout based on commercial components for reliability and fast prototyping. We were able to reach and sustain a readout rate higher than 60 kHz for 18 detectors. In this contribution a general description of the architecture, together with the main performances in terms of amplitude and phase noise are given.
A new facility instrument open to the scientific community is MISTRAL. The MIllimeter Sardinia radio Telescope Receiver based on Array of Lumped elements KIDs (MISTRAL) is a millimetric multi–pixel camera, mounted at the Gregorian focus of the Sardinia Radio Telescope (SRT), working in the W-band that will be able to study many scientific cases, from the ‘missing baryons’ problem to extragalactic astrophysics, morphology of galaxy cluster and the search of the Cosmic Web through high angular resolution measurements of the Sunyaev-Zel’dovich effect. We present the current state of the map-making and data filtering software that we plan to use for future observations. This software aims to analyze the simulated observations of a target, filter the data from instrumental noise and produce a map, employing a customized common mode removal.
The Millimeter Sardinia radio Telescope Receiver based on Array of Lumped elements KIDs (MISTRAL) is a new high resolution, wide field-of-view camera that was successfully installed in May 2023 at the Sardinia Radio Telescope (SRT). SRT is a 64m fully steerable gregorian radio telescope, and it underwent an upgrade funded by a National Operational Program (PON) with the aim to expand the fleet of receivers of the radio telescope in order to cover frequency up to the W–band. The W-band sky has been extensively studied by Cosmic Microwave Background experiments, both ground-based (ACT, SPT) and satellite-based (WMAP, Planck). However, their resolution is limited to ≈1′ from ground telescopes and ≈10′ from satellite at best. With this new instrument, we aim to map the microwave sky at a resolution of ≈12′′, a capability only shared by few instruments in the world, unlocking the exploration of a plethora of science cases from the recently upgraded SRT. The heart of MISTRAL is a ≈90mm silicon focal plane populated with 415 cryogenic Lumped Elements Kinetic Inductance Detectors (LEKIDs). These detectors are copuled with the telescope using a cold (4K) re-imaging optical system, producing a diffraction limited field-of-view of 4 ′. The system is enclosed in a custom, four stage cryostat, built with strict requirements on its size, in order to fit on the rotating turret that allows to switch the receivers to be quickly moved in and out of the gregorian focus position. The sub-K stage cools the detectors down to 200-240 mK. MISTRAL is now installed on the gregorian focus of SRT and is undergoing the technical commissioning, and will soon enter the scientific commissioning phase. In this contribution we will survey the subsystems of MISTRAL and their performance at the focus of the radio telescope, and report the current status of the technical commissioning.
In this work, we present the design and manufacturing of the two multi-mode antenna arrays of the COSMO experiment and the preliminary beam pattern measurements of their fundamental mode compared with simulations.
COSMO is a cryogenic Martin-Puplett Fourier Transform Spectrometer that aims at measuring the isotropic y-type spectral distortion of the Cosmic Microwave Background from Antarctica, by performing differential measurements between the sky and an internal, cryogenic reference blackbody. To reduce the atmospheric contribution, a spinning wedge mirror performs fast sky-dips at varying elevations while fast, low-noise Kinetic Inductance detectors scan the interferogram.
Two arrays of antennas couple the radiation to the detectors. Each array consists of nine smooth-walled multi-mode feed-horns, operating in the 120−180 GHz and 210−300 GHz range, respectively. The multi-mode propagation helps increase the instrumental sensitivity without employing large focal planes with hundreds of detectors. The two arrays have a step-linear and a linear profile, respectively, and are obtained by superimposing aluminum plates made with CNC milling. The simulated multi-mode beam pattern has a ~ 20° − 26° FWHM for the low-frequency array and ~16° FWHM for the high-frequency one. The side lobes are below −15 dB.
To characterize the antenna response, we measured the beam pattern of the fundamental mode using a Vector Network Analyzer, in far-field conditions inside an anechoic chamber at room temperature. We completed the measurements of the low-frequency array and found a good agreement with the simulations. We also identified a few non-idealities that we attribute to the measuring setup and will further investigate. A comprehensive multi-mode measurement will be feasible at cryogenic temperature once the full receiver is integrated.
Federico Cacciotti, Alessandro Paiella, Camille Avestruz, Ritoban Basu Thakur, Elia Battistelli, Paolo de Bernardis, Esra Bulbul, Fabio Columbro, Alessandro Coppolecchia, Scott Cray, Giuseppe D'Alessandro, Marco De Petris, Shaul Hanany, Luca Lamagna, Erwin Lau, Silvia Masi, Giorgio Pettinari, Francesco Piacentini, Jack Sayers, Irina Zhuravleva
OLIMPO is a 2.6m balloon–borne telescope intended to observe, with high–angular resolution, the millimeter and sub–millimeter sky from the Antarctic stratosphere. It will allow us to study the dynamics of galaxy cluster formation and to characterize the intergalactic medium up to the cluster outskirt through the Sunyaev-Zel’dovich effect. OLIMPO utilizes four arrays of kinetic inductance detectors (KIDs), in the 145, 250, 350 and 460 GHz bands, operated at about 300 mK. OLIMPO has already flown, in a technological flight, in 2018 from Svalbard, Norway, proving for the first time that KIDs are capable to withstand the demanding conditions on high altitude balloons. KIDs are superconducting, low–temperature detectors suited for this kind of applications due to their intrinsic capability to be frequency–domain multiplexed, enabling very high–sensitivity sky surveys. In this work, we present the design, optimization and laboratory characterization of the 313–pixel array for the OLIMPO 350 GHz frequency band. We showcase results of the electrical characterization (electrical responsivity and the measurement of the quasiparticle lifetime) and the optical characterization (optical responsivity and optical efficiency) accomplished with a 4K cooled black body.
The MISTRAL instrument is a cryogenic, W-band camera consisting of 415 lumped element kinetic inductance detectors. In a significant milestone achieved in May 2023, MISTRAL was successfully installed at the Gregorian focus of the Sardinia Radio Telescope, a 64m aperture telescope in Italy. MISTRAL has a focal plane of ~ 94mm in diameter, resulting in an instantaneous field of view ~ 4 arcmin. To preserve the high angular resolution of the telescope, which is ~ 12 arcsec, the focal plane sampling has been tuned to 4.2 mm, corresponding to a pixel separation of ~ 10.6 arcsec. The remarkable combination of high angular resolution and wide instantaneous field of view makes MISTRAL an exceptionally versatile tool for continuum surveys of wide areas of the sky. Its unique capabilities significantly enhance the observational capacity of the Sardinia Radio Telescope. The lumped element kinetic inductance detectors of MISTRAL are obtained from a titanium-aluminum bilayer 10 + 30nm thick on a single 100 mm–diameter Silicon wafer with thickness 235 μm. They exhibit a critical temperature of 945mK and are optimized to operate within the temperature range of 200 to 240 mK. The feedline is made of an aluminum 21nm thick and has a critical temperature of 1.35 K. We discuss the design, electrical, and optical characterization of the detector array, placing specific emphasis on the yield, the pixel identification on the array, the optical performance, and the calibration procedures.
Tunable entangled photon emitters based on cavity-enhanced GaAs quantum dots on micromachined piezoelectric substrates was recorded at SPIE Optics + Photonics held in San Diego, California, United States 2022.
The EUV reflectometer facility available at the Institute for Photonics and Nanotechnologies-CNR Padua (Italy) has been characterized in terms of Stokes’ parameters at two wavelengths of particular interest for space applications, the hydrogen Lyman alpha at 121.6 nm and 160 nm. The design and the performances of a polarizer based on four gold coated mirrors and coupled with the facility are also described. The whole system consisting of the reflectometer and the polarizer can be used to test mirrors, polarizers and phase retarders in the EUV range by means of the Mueller Matrix formalism, and even to investigate compositions, interfaces and structure of thin films and optical coatings.
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