Precise Measurement of Cosmic Microwave Background Polarization with a Large Superconducting Detector Array

2014 Fiscal Year Final Research Report

• Project/Area Number: 24684017
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Partial Multi-year Fund
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: High Energy Accelerator Research Organization
• Principal Investigator: HASEGAWA MASAYA 大学共同利用機関法人高エネルギー加速器研究機構, 素粒子原子核研究所, 助教 (60435617)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 宇宙背景放射 / インフレーション / 原始重力波 / 偏光 / 重力レンズ / ニュートリノ質量 / 検出器開発

Outline of Final Research Achievements

The main goals of this study are precise measurement of cosmic microwave background (CMB) polarization with POLARBEAR-1 towards the detection of the special polarization pattern originating primordial gravitational wave (B-modes), and development of a new receiver POLARBEAR-2 which has six times higher mapping speed.
We successfully measured the lensing B-mode power spectrum with CMB data alone at 4.7sigma level. Systematic errors are well controlled, and we proved our technology and observing strategy are promising for the primordial B-mode search.
The development of POLARBEAR-2 receiver is almost completed. One of the challenges is to cool down the large focal plane with more than 7600 detectors to 250mK. We constructed a dedicated optical system with novel lenses and filter with alumina, and successfully controlled the thermal load onto the focal plane. After some laboratory testing, we plan to deploy POLARBEAR-2 in Chile early spring next year, and start data-taking in next summer.

Free Research Field

宇宙物理