The optical system of the Tenerife Microwave Spectrometer: a window for observing the 10–20 GHz sky spectra

Abstract

The TMS optical system is based on a decentered dual-reflector system in a Gregorian configuration to observe with an angular resolution of less than 2°. The primary goal of the present study is to evaluate the final design and verify that it satisfies the design requirements. We aim for low cross-polarization (-30 dB), low sidelobe (-25 dB) levels, and a stable beam in terms of shape (low ellipticity) and size over a full octave bandwidth (10–20 GHz). We performed both ray-tracing and full-wave simulations using the CST Studio software in order to investigate the system behaviour. We gave special attention to the beam frequency variation and polarization leakage. We have characterized the effects on the radiation pattern produced by the cryostat window. We present the final design of the TMS optical system, as well as a complete study of the system's performance in terms of cross-polarization, sidelobes, ellipticity and beamwidth. We discuss the effects of sidelobes and study the need for a baffle.

Relic neutrino decay solution to the excess radio background

“…Notice that an explanation of the excess radio background detected by ARCADE 2 in term of relic neutrino decays (or even in terms of any other relic particle decays), necessarily implies E ≤ ∆m 1 and, therefore, the existence of an endpoint E max = ∆m 1 . This is a very clear prediction of the model that will be tested by next experiments aiming at detecting deviations from CMB such as PIXIE, with low threshold ν PIXIE = 30 GHz [18] and new radio interferometers such as TMS, with low threshold ν TMS = 10 GHz [21,22]. This implies that, for a fixed value of ∆m 1 , the model predicts no excess radiation at all energies E > ∆m 1 , so that the standard case is recovered.…”

“…1 Some of these explanations are also constrained by other cosmological observations [16,17] but additional data will be necessary to draw firm conclusions. In this respect, it is interesting that more measurements will come both from CMB experiments with a smaller low frequency threshold than FIRAS, such as the Primordial Inflation Explorer (PIXIE) [18] or its more advanced versions Super-PIXIE [19] and VOYAGE 2050 [20], that will measure deviations of the CMB spectrum from thermal down to 30 GHz, and from radio interferometers such as the Tenerife Microwave Spectrometer (TMS) that will cover the 10-20 GHz frequency range [21,22].…”