GroundBIRD : A CMB polarization experiment with MKID arrays
  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 $l \sim 6$. 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.
