Measuring the CMB spectral distortions with COSMO: the multi-mode antenna system ...

• Main Authors: Manzan, E., Albano, L., Franceschet, C., Battistelli, E. S., de Bernardis, P., Bersanelli, M., Cacciotti, F., Capponi, A., Columbro, F., Conenna, G., Coppi, G., Coppolecchia, A., D'Alessandro, G., De Gasperis, G., De Petris, M., Gervasi, M., Isopi, G., Lamagna, L., Limonta, A., Marchitelli, E., Masi, S., Mennella, A., Montonati, F., Nati, F., Occhiuzzi, A., Paiella, A., Pettinari, G., Piacentini, F., Piccirillo, L., Pisano, G., Tucker, C., Zannoni, M.
• Format: Report
• Language: unknown
• Published: arXiv 2024
• Subjects: Instrumentation and Methods for Astrophysics astro-ph.IM; Cosmology and Nongalactic Astrophysics astro-ph.CO; FOS Physical sciences; Antarc*; Antarctica
• Online Access: https://dx.doi.org/10.48550/arxiv.2406.09349; https://arxiv.org/abs/2406.09349

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 ... : To appear in Proceedings of the SPIE Astronomical Telescopes + Instrumentation, 2024 ...