The axion is a long-postulated boson that can simultaneously solve two crucial problems of Modern Physics: the unexpected charge and parity symmetry observed in the strong nuclear force and the enigma of dark matter. The Dark-photons and Axion- Like particles Interferometer (DALI) is a proposal for a new generation axion detector designed to probe dark matter in a broad band that ranges from microwaves to mm-wave employing a tunable multilayer Fabry-Pérot interferometer. This frequency range remains poorly explored owing to the technological challenges associated with the development of the experimental approach required to scan it. The DALI instrument, which is currently in the prototyping phase, imports technology and techniques from radio astronomy. This apparatus may also be sensitive to other hypothetical particles, such as the dark photon.
A resonator is needed to enhance the weak signal originating from axion to photon conversion by the action of an external magnetic field. It is composed of ceramic plates and an electro-mechanical tuner. A fixed-plate prototype of a resonator has been manufactured and tested in an optical laboratory setup devised to excite it with a horn antenna and observe its resonant spectral feature from reflectivity measurements. A detailed description of the setup, the post-processing of the data and the observed resonant structure are treated in this work.
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.
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