Polarization anisotropies on the cosmic microwave background (CMB) is an interesting target for astroparticle physics. Especially, the parity-odd component, the so-called B-mode, in degree scale is a unique probe of primordial gravitational waves from the cosmic inflation. The POLARBEAR experiment is a ground-based CMB polarization measurement at the Atacama Desert in Chile with 1,274 transition-edge-sensor (TES) bolometers sensitive to the 150 GHz band on a 2.5 m aperture telescope. One of the challenges for the degree-scale measurement is the mitigation of the low-frequency noise, the so-called 1/f noise. Since 2014, POLARBEAR has employed a polarization modulation technique using a continuously rotating half-wave plate. The same technique is used in the Atacama B-mode Search (ABS) experiment at Princeton and the small aperture telescopes in the Simons Observatory (SO) experiment. In POLARBEAR, however, we find that there are remaining 1/f noises due to instrumental leakages and polarized clouds. I am interested in improving the characterization of the 1/f noise using the ABS data and also developing a new cloud monitor, which will contribute to SO to measure inflationary B-modes.
Gravity Group Lunch Seminar, Satoru Takakura | IPMU (Dicke Candidate) "Measurements of CMB polarization with the polarization modulation technique"