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Probing primordial gravitational waves: Ali CMB Polarization Telescope

Research output: Contribution to journalReview articlepeer-review

  • Hong Li
  • Si-Yu Li
  • Yang Liu
  • Yong-Ping Li
  • Yifu Cai
  • Mingzhe Li
  • Gong-Bo Zhao
  • Cong-Zhan Liu
  • Zheng-Wei Li
  • He Xu
  • Di Wu
  • Yong-Jie Zhang
  • Zu-Hui Fan
  • Yong-Qiang Yao
  • Chao-Lin Kuo
  • Fang-Jun Lu
  • Xinmin Zhang

In this paper, we will give a general introduction to the Ali CMB Polarization Telescope (AliCPT) project, which is a Sino-US joint project led by the Institute of High Energy Physics and involves many different institutes in China. It is the first ground-based Cosmic Microwave Background (CMB) polarization experiment in China and an integral part of China's Gravitational-wave Program. The main scientific goal of the AliCPT project is to probe the primordial gravitational waves (PGWs) originating from the very early Universe. The AliCPT project includes two stages. The first stage, referred to as AliCPT-1, is to build a telescope in the Ali region of Tibet at an altitude of 5250 meters. Once completed, it will be the highest ground-based CMB observatory in the world and will open a new window for probing PGWs in the northern hemisphere. The AliCPT-1 telescope is designed to have about 7000 transition-edge sensor detectors at 95 GHz and 150 GHz. The second stage is to have a more sensitive telescope (AliCPT-2) with more than 20 000 detectors. Our simulations show that AliCPT will improve the current constraint on the tensor-to-scalar ratio r by one order of magnitude with three years' observation. Besides the PGWs, AliCPT will also enable a precise measurement of the CMB rotation angle and provide a precise test of the CPT symmetry. We show that three years' observation will improve the current limit by two orders of magnitude.

Original languageEnglish
Pages (from-to)145-154
Number of pages10
JournalNational Science Review
Issue number1
Early online date5 Feb 2018
Publication statusPublished - 1 Jan 2019


  • AliCPT

    Rights statement: This is a pre-copyedited, author-produced version of an article accepted for publication in National Science Review following peer review. The version of record Hong Li, Si-Yu Li, Yang Liu, Yong-Ping Li, Yifu Cai, Mingzhe Li, Gong-Bo Zhao, Cong-Zhan Liu, Zheng-Wei Li, He Xu, Di Wu, Yong-Jie Zhang, Zu-Hui Fan, Yong-Qiang Yao, Chao-Lin Kuo, Fang-Jun Lu, Xinmin Zhang, Probing primordial gravitational waves: Ali CMB Polarization Telescope, National Science Review, Volume 6, Issue 1, January 2019, Pages 145–154 is available online at:

    Accepted author manuscript (Post-print), 9.73 MB, PDF document

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