• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to project page

2021 Fiscal Year Final Research Report

Cryogenic polarization properties measurement of a half-wave plate for polarization modulator in CMB polarization experiments

Research Project

  • PDF
Project/Area Number 19K14732
Research Category

Grant-in-Aid for Early-Career Scientists

Allocation TypeMulti-year Fund
Review Section Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
Research InstitutionOkayama University (2021)
The University of Tokyo (2019-2020)

Principal Investigator

SAKURAI YUKI  岡山大学, 自然科学学域, 特任助教 (50780847)

Project Period (FY) 2019-04-01 – 2022-03-31
KeywordsCMB / インフレーション / 宇宙物理 / 偏光変調器 / 半波長板 / 極低温 / ミリ波
Outline of Final Research Achievements

In this research project, we aim to measure the precise polarization characteristics of a half-wave plate for polarization modulator used in a cosmic microwave background (CMB) polarization experiment to search for cosmic inflation. We constructed a millimeter-wave optical measurement setup by using a vector network analyzer and developed cryogenic optical setup combined with 4K cryostat. We developed anti-reflective coatings on a sapphire half-wave plate and measured its polarization characteristics (transmittance, reflectance, and modulation efficiency) by using the constructed optical setup. We have succeeded in developing a sapphire achromatic half-wave plate used in ground experiments and in evaluating its characteristics. In addition, we succeeded in evaluating polarization characteristics at cryogenic temperatures by combining an optical measurement system and a rotation mechanism. The sensitivity of the CMB experiments will be increased by using these results in analysis.

Free Research Field

宇宙物理学、高エネルギー物理学

Academic Significance and Societal Importance of the Research Achievements

宇宙マイクロ波背景放射の観測によって、これまで多くの初期宇宙の情報をもたらしてきた。その偏光観測によって、宇宙のインフレーションの実験的検証が可能と予言されているが、そのためには実験のさらなる高感度化が不可欠である。そのためには、実験装置の中でも鍵となる偏光変調器の較正、系統誤差の正確な評価が求められる。本研究では、その主要部である半波長板の反射防止の開発から、常温、低温における偏光特性評価までを行った。将来実験における実際の観測が進み、本研究の測定結果が解析に使用されることで、実験の高感度化によるインフレーション検証の早期化に貢献した。

URL: 

Published: 2023-01-30  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi