1研究背景。大地震往往会带来巨大的人员和财产损失。通过多年的观测、实验和理论研究,科学家们对地震的孕育环境、成核和破裂过程、断层介质性质及其变化等的认识取得显著进步(如Kato and Ben-Zion,2021)。然而,有时在即使知道哪里会...1研究背景。大地震往往会带来巨大的人员和财产损失。通过多年的观测、实验和理论研究,科学家们对地震的孕育环境、成核和破裂过程、断层介质性质及其变化等的认识取得显著进步(如Kato and Ben-Zion,2021)。然而,有时在即使知道哪里会发生大地震的情况下,科学家们仍然无法知道地震到底什么时候会发生(如Hall,2023)。问题的关键是我们还没有发现可靠的地震发生的前兆特征。利用Grace卫星重力观测,通过对Tohoku-Oki地震前后的重力信号分析,Panet等(2018)发现,重力变化很好地展示了本次地震横跨整个断层的形变从深部向浅部迁移的过程。观测显示,重力场在几个月前就开始变化,这种变化与孕震过程基本一致。该研究显示出重力场中可能包含着与地震孕震过程中的物质迁移密切相关的地震短临前兆信号。但是,Tohoku-Oki地震出现的这种重力前兆信号,是否是一种普遍现象,是否会在今后的其他大地震中出现,是一个值得深入研究和探讨的问题。展开更多
Compact atomic gravimeters are the potential next generation precision instruments for gravity survey from fundamental research to broad field applications.We report the calibration results of our home build compact a...Compact atomic gravimeters are the potential next generation precision instruments for gravity survey from fundamental research to broad field applications.We report the calibration results of our home build compact absolute atomic gravimeter USTC-AG02 at Changping Campus,the National Institute of Metrology(NIM),China in January 2019.The sensitivity of the atomic gravimeter reaches 35.5μGal/√Hz(1μGal=1×10-8 m/s2)and its long-term stability reaches 0.8μGal for averaging over 4000 seconds.Considering the statistical uncertainty,the dominant instrumental systematic errors and environmental effects are evaluated and corrected within a total uncertainty(2σ)of 15.3μGal.After compared with the reference g value given by the corner cube gravimeter NIM-3A,the atomic gravimeter USTC-AG02 reaches the degree of equivalence of 3.7μGal.展开更多
For an atomic gravimeter,the measured value of the Earth’s gravity acceleration g is the projection of the local gravity on the direction of Raman laser beams.To accurately measure the g,the Raman laser beams should ...For an atomic gravimeter,the measured value of the Earth’s gravity acceleration g is the projection of the local gravity on the direction of Raman laser beams.To accurately measure the g,the Raman laser beams should be parallel to the g direction.We analyze the tilt effect of the Raman beams on g measurement and present a general method for the tilt adjustment.The systematic error caused by the tilt angle is evaluated as 0(+0,0.8)µGal(1µGal=10 nm/s^2)and the drift is also compensated in real time.Our method is especially suitable for the portable atomic gravimeter which focuses on the mobility and field applications.展开更多
The gravimeter based on atom interferometry has potential wide applications on building gravity networks and geophysics as well as gravity assisted navigation. Here, we demonstrate experimentally a portable atomic gra...The gravimeter based on atom interferometry has potential wide applications on building gravity networks and geophysics as well as gravity assisted navigation. Here, we demonstrate experimentally a portable atomic gravimeter operating in the noisy urban environment. Despite the influence of noisy external vibrations, our portable atomic gravimeter reaches a sensitivity as good as 65 μGal/√Hz and a resolution of 1.1 μGal after 4000 s integration, being comparable to state-of-the-art atomic gravimeters. Our achievement paves the way for bringing the portable atomic gravimeter to field applications.展开更多
文摘1研究背景。大地震往往会带来巨大的人员和财产损失。通过多年的观测、实验和理论研究,科学家们对地震的孕育环境、成核和破裂过程、断层介质性质及其变化等的认识取得显著进步(如Kato and Ben-Zion,2021)。然而,有时在即使知道哪里会发生大地震的情况下,科学家们仍然无法知道地震到底什么时候会发生(如Hall,2023)。问题的关键是我们还没有发现可靠的地震发生的前兆特征。利用Grace卫星重力观测,通过对Tohoku-Oki地震前后的重力信号分析,Panet等(2018)发现,重力变化很好地展示了本次地震横跨整个断层的形变从深部向浅部迁移的过程。观测显示,重力场在几个月前就开始变化,这种变化与孕震过程基本一致。该研究显示出重力场中可能包含着与地震孕震过程中的物质迁移密切相关的地震短临前兆信号。但是,Tohoku-Oki地震出现的这种重力前兆信号,是否是一种普遍现象,是否会在今后的其他大地震中出现,是一个值得深入研究和探讨的问题。
基金Project supported by the National Key R&D Program of China(Grant No.2016YFA0301601)the National Natural Science Foundation of China(Grant No.11674301)+1 种基金Anhui Initiative in Quantum Information Technologies,China(Grant No.AHY120000)Shanghai Municipal Science and Technology Major Project,China(Grant No.2019SHZDZX01).
文摘Compact atomic gravimeters are the potential next generation precision instruments for gravity survey from fundamental research to broad field applications.We report the calibration results of our home build compact absolute atomic gravimeter USTC-AG02 at Changping Campus,the National Institute of Metrology(NIM),China in January 2019.The sensitivity of the atomic gravimeter reaches 35.5μGal/√Hz(1μGal=1×10-8 m/s2)and its long-term stability reaches 0.8μGal for averaging over 4000 seconds.Considering the statistical uncertainty,the dominant instrumental systematic errors and environmental effects are evaluated and corrected within a total uncertainty(2σ)of 15.3μGal.After compared with the reference g value given by the corner cube gravimeter NIM-3A,the atomic gravimeter USTC-AG02 reaches the degree of equivalence of 3.7μGal.
基金Project supported by the National Key R&D Program of China(Grant No.2016YFA0301601)the National Natural Science Foundation of China(Grant No.11674301)+1 种基金Anhui Initiative in Quantum Information Technologies,China(Grant No.AHY120000)Shanghai Municipal Science and Technology Major Project,China(Grant No.2019SHZDZX01).
文摘For an atomic gravimeter,the measured value of the Earth’s gravity acceleration g is the projection of the local gravity on the direction of Raman laser beams.To accurately measure the g,the Raman laser beams should be parallel to the g direction.We analyze the tilt effect of the Raman beams on g measurement and present a general method for the tilt adjustment.The systematic error caused by the tilt angle is evaluated as 0(+0,0.8)µGal(1µGal=10 nm/s^2)and the drift is also compensated in real time.Our method is especially suitable for the portable atomic gravimeter which focuses on the mobility and field applications.
基金supported by the National Key R&D Program of China (No. 2016YFA0301601)National Natural Science Foundation of China (No. 11674301)+3 种基金Strategic Priority Research Program on Space Science of the Chinese Academy of Sciences (No. XDA15020000)Anhui Initiative in Quantum Information Technologies (No. AHY120000)Shanghai Municipal Science and Technology Major Project (No. 2019SHZDZX01)funded by the Youth Program of National Natural Science Foundation of China (No. 11804019)。
文摘The gravimeter based on atom interferometry has potential wide applications on building gravity networks and geophysics as well as gravity assisted navigation. Here, we demonstrate experimentally a portable atomic gravimeter operating in the noisy urban environment. Despite the influence of noisy external vibrations, our portable atomic gravimeter reaches a sensitivity as good as 65 μGal/√Hz and a resolution of 1.1 μGal after 4000 s integration, being comparable to state-of-the-art atomic gravimeters. Our achievement paves the way for bringing the portable atomic gravimeter to field applications.
