GroundBIRD: A CMB Polarization Experiment with MKID Arrays

Abstract

GroundBIRD is a ground-based experiment for the precise observation of the polarization of the cosmic microwave background (CMB). To achieve high sensitivity at large angular scale, we adopt three features in this experiment: fast rotation scanning, microwave kinetic inductance detector (MKID) and cold optics. The rotation scanning strategy has the advantage to suppress 1/ f noise. It also provides a large sky coverage of 40%, which corresponds to the large angular scales of l ∼ 6. This allows us to constrain the tensor-to-scalar ratio by using low l B-mode spectrum. The focal plane consists of 7 MKID arrays for two target frequencies, 145 GHz and 220 GHz band. There are 161 pixels in total, of which 138 are for 144 GHz and 23 are for 220 GHz. This array is currently under development and the prototype will soon be evaluated in telescope. The GroundBIRD telescope will observe the CMB at the Teide observatory. The telescope was moved from Japan to Tenerife and is now under test. We present the status and plan of the GroundBIRD experiment.

The large scale polarization explorer (LSPE) for CMB measurements: performance forecast

“…In addition to serving as low frequency monitor for LSPE, Strip also will complement two existing CMB experiments in Tenerife, QUIJOTE [38] and GroundBIRD [39], by observing in different frequency bands: 10-40 GHz for QUIJOTE, 40-95 GHz for Strip, and 145-225 GHz for Ground-BIRD. All three Tenerife projects (QUIJOTE, LSPE-Strip and GroundBIRD) aim at measuring approximately the same area in the Northern sky and at degree scales, opening the possibility of future combined analyses, including useful redundancy for cross-checks of systematic effects.…”

Applications for Microwave Kinetic Induction Detectors in Advanced Instrumentation

“…There are multiple CMB B-mode experiments ongoing and in late planning phases at the moment, and MKIDs are considered for several of them and already utilized in some. GroundBIRD [77][78][79] is searching for the CMB B-mode polarization with a 30 cm telescope that rotates rapidly (about 20 rounds per minute) on a horizontal platform to enhance noise suppression. It uses 161 MKID pixels in two bands centered around 145 GHz (2.1 mm, 138 pixels) and 220 GHz (1.4 mm, 23 pixels) and will start observing from Teide Observatory, Tenerife soon.…”

Superconducting detectors for rare event searches in experimental astroparticle physics

“…In principle, more than a thousand resonators can be read out by a single feedline. Because of their highly multiplexing capability and low noise, KIDs have already been employed in many instruments to detect astronomical signals ranging from the millimeter scale to the ultraviolet (UV) [159,160].…”