The QUIJOTE (Q-U-I JOint TEnerife) experiment combines the operation of two radio-telescopes and three instruments working in the microwave bands from 10 to 47 GHz at the Teide Observatory, Tenerife, which has already been presented in previous SPIE meetings. The new Multi Frequency Instrument (MFI2) led by the Instituto de Astrofísica de Canarias (IAC) aims to characterize the polarized emission of the Cosmic Microwave Background (CMB), as well as Galactic and extra-Galactic sources, at medium and large angular scales. This instrument has five polarimeters, three working in the microwave band of 10-15 GHz, and two working in the microwave band of 15-20 GHz. The instrument is composed of a cylindrical aluminum 6061-T6 cryostat cooled by a closed Gifford-McMahon helium cycle cryocooler with two stage shields (first stage at 30 K, and second stage at 10 K). The opto-mechanical system consists of five horns aligned with the focal plane of the telescope where the signal enters the instrument, each horn is followed by an OMT, a 90º Hybrid and two LNAs cooled down below 20 K, all of which represents the Front-End Module (FEM). This signal leaves the instrument by a feedthrough where the Back End Module (BEM) waits at room temperature to process the signals.
The QUIJOTE (Q-U-I joint Tenerife) experiment combines the operation of two radio-telescopes and three instruments working in the microwave bands 10–20 GHz, 26–36 GHz and 35–47 GHz at the Teide Observatory, Tenerife, and has already been presented in previous SPIE meetings (Hoyland, R. J. et al, 2012; Rubi˜no-Mart´ın et al., 2012). The Cosmology group at the IAC have designed a new upgrade to the MFI instrument in the band 10–20 GHz. The aim of the QUIJOTE telescopes is to characterise the polarised emission of the cosmic microwave background (CMB), as well as galactic and extra-galactic sources, at medium and large angular scales. This MFI2 will continue the survey at even higher sensitivity levels. The MFI2 project led by the Instituto de Astrof´ısica de Canarias (IAC) consists of five polarimeters, three of them operating in the sub-band 10–15 GHz, and two in the sub-band 15–20 GHz. The MFI2 instrument is expected to be a full two–three times more sensitive than the former MFI. The microwave complex correlator design has been replaced by a simple correlator design with a digital back-end based on the latest Xilinx FPGAs (ZCU111). During the first half of 2019 the manufacture of the new cryostat was completed and since then the opto-mechanical components have been designed and manufactured. It is expected that the cryogenic front-end will be completed by the end of 2022 along with the FPGA acquisition and observing system. This digital system has been employed to be more robust against stray ground-based and satellite interference, having a frequency resolution of 1 MHz
The Tenerife Microwave Spectrometer (TMS) is part of a renewed effort to study and characterize the CMB frequency distribution. The spectrometer is based on a pseudo-correlation architecture with two 10–20 GHz radiometer chains making use of both orthogonal linear polarizations, and will observe in this band with an angular and frequency resolutions of 3° and 1 MHz. The optical arrangement includes two corrugated feedhorns, one facing an internal calibrator to provide a cold reference signal, and the other pointing to the sky through the cryostat window by means of an offset-fed reflector. The optical system provides optimal cross-polarization properties (≤-30 dB) and symmetric beams, with minimum frequency dependence. The readout system is based on a SoC FPGA, providing fast data acquisition, high spectral resolution and stability. We present the current status of the TMS instrument, having described the scientific case of this instrument in the accompanying publication.
The Tenerife Microwave Spectrometer (TMS) is a new 10-20 GHz experiment that will be installed at the Teide Observatory (Tenerife, Spain), next to the QUIJOTE CMB experiment. The main TMS scientific driver is to accurately measure absolute distortions of the sky spectrum in the 10-20 GHz frequency range, with special emphasis on the characterization of the absolute synchrotron monopole from our Galaxy, and the possible deviations of the CMB spectrum from a pure blackbody law. TMS will provide an absolute calibration for the QUIJOTE experiment, and it will also serve as a prototype for future instruments of its type, both ground-based and satellites. Among its new instrumental design is an octave bandwidth high quality cryogenic front-end, a thermally stabilized cold black body and a new design of wide-band Fourier transform spectrometer. The spectrometer will have a resolution of 250 MHz, giving 40 spectrally stable sub-bands.
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