Total power horn-coupled 150 GHz LEKID array for space applications

TL;DR

This paper presents the development and characterization of a 150 GHz LEKID array optimized for space-based CMB measurements, demonstrating photon-noise limited performance suitable for future satellite missions.

Contribution

It introduces a total power LEKID array design optimized for space applications, with detailed fabrication, calibration, and performance validation under space-like conditions.

Findings

Almost all detectors are photon-noise limited at 3.6 K background.

Weak sensitivity to cosmic rays demonstrated in flight conditions.

Array suitable for precision space-based CMB spectral distortion measurements.

Abstract

We have developed two arrays of lumped element kinetic inductance detectors working in the D-band, and optimised for the low radiative background conditions of a satellite mission aiming at precision measurements of the Cosmic Microwave Background (CMB). The first detector array is sensitive to the total power of the incoming radiation to which is coupled via single-mode waveguides and corrugated feed-horns, while the second is sensitive to the polarisation of the radiation thanks to orthomode transducers. Here, we focus on the total power detector array, which is suitable, for instance, for precision measurements of unpolarised spectral distortions of the CMB, where detecting both polarisations provides a sensitivity advantage. We describe the optimisation of the array design, fabrication and packaging, the dark and optical characterisation, and the performance of the black-body calibrator used for the optical tests. We show that almost all the detectors of the array are photon-noise limited under the radiative background of a 3.6 K black-body. This result, combined with the weak sensitivity to cosmic rays hits demonstrated with the OLIMPO flight, validates the idea of using lumped elements kinetic inductance detectors for precision, space-based CMB missions.