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Recent calculations of the order (Z\alpha)^4(m/M)Ry pure recoil correction to hydrogen energy levels are critically revised. The origins of errors made in the previous works are elucidated. In the framework of a successive approach, we…

Atomic Physics · Physics 2009-10-30 A. Yelkhovsky

We propose an effective method to decrease the Ramsey linewidth of microwave atomic clock by tracking the coherent atomic phase through nondestructive measurement. The free evolution time T between two Ramsey pulses is divided into N…

Atomic Physics · Physics 2017-02-17 Gongxun Dong , Jinda Lin , Jianliao Deng , Yuzhu Wang

An interferometer has been used to measure the surface profile of generic object. Frequency scanning interferometry has been employed to provide unambiguous phase readings, to suppress etalon fringes, and to supersede phase-shifting. The…

Instrumentation and Detectors · Physics 2016-11-21 Marek Peca , Pavel Psota , Petr Vojtíšek , Vít Lédl

This paper introduces a new algorithm to improve the accuracy of numerical phase-averaging in oscillatory, multiscale, differential equations. Phase-averaging is a timestepping method which averages a mapped variable to remove highly…

Numerical Analysis · Mathematics 2024-11-07 Timothy C. Andrews , Beth A. Wingate

The Earth's atmosphere is comprised of turbulent layers that result in speckled and blurry images from ground-based visible and infrared observations. Adaptive Optics (AO) systems are employed to measure the perturbed wavefront with a…

Instrumentation and Methods for Astrophysics · Physics 2024-10-03 Zhenxi Du , Saavidra Perera , Daniel Levinstein , Quinn Konopacky , Alex Madurowicz , Bruce Macintosh , Lisa Poyneer , Richard Wilson , Ollie Farley

We present an analysis of Epoch of Reionization data from Phase II of the Murchison Widefield Array using the \texttt{simpleDS} delay spectrum pipeline. Prior work analyzed the same observations using the FHD/$\varepsilon$ppsilon imaging…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-05 Matthew Kolopanis , Jonathan Pober , Daniel C. Jacobs , Samantha McGraw

A new high time resolution observing mode for the Murchison Widefield Array (MWA) is described, enabling full polarimetric observations with up to 30.72 MHz of bandwidth and a time resolution of ~0.8 $\mu$s. This mode makes use of a…

Instrumentation and Methods for Astrophysics · Physics 2020-08-26 S. J. McSweeney , S. M. Ord , N. D. R. Bhat , B. W. Meyers , S. E. Tremblay , J. Jones , B. Crosse , K. R. Smith

Fusion experiments rely heavily on the measurement of the line-integrated electron density by interferometry for density feed-back control. In recent years the discharge length has increased dramatically and is continuing to rise, resulting…

Instrumentation and Detectors · Physics 2019-11-14 K. J. Brunner , J. Knauer , J. Meineke , M. Stern , M. Hirsch , B. Kursinski , R. C. Wolf , the W7-X team

Compact interferometers, called phasemeters, make it possible to operate over a large range while ensuring a high resolution. Such performance is required for the stabilization of large instruments dedicated to experimental physics such as…

Instrumentation and Methods for Astrophysics · Physics 2018-12-03 Jennifer Watchi , Sam Cooper , Binlei Ding , Conor M. Mow-Lowry , Christophe Collette

Atmospheric turbulence is a serious problem for ground-based interferometers. It places tight limits on both sensitivity and measurement precision. Phase referencing is a method to overcome these limitations via the use of a bright…

Astrophysics · Physics 2015-06-24 Benjamin F. Lane , Matthew W. Muterspaugh

Accurate antenna beam models are critical for radio observations aiming to isolate the redshifted 21cm spectral line emission from the Dark Ages and the Epoch of Reionization and unlock the scientific potential of 21cm cosmology. Past work…

Radio pulses from pulsars are affected by plasma dispersion, which results in a frequency-dependent propagation delay. Variations in the magnitude of this effect lead to an additional source of red noise in pulsar timing experiments,…

Millimeter-wave (mmWave) radar enables contactless respiratory sensing,yet fine-grained monitoring is often degraded by nonstationary interference from body micromotions.To achieve micromotion interference removal,we propose…

Image and Video Processing · Electrical Eng. & Systems 2026-03-24 Yong Wang , Qifan Shen , Bao Zhang , Zijun Huang , Chengbo Zhu , Shuai Yao , Qisong Wu

Time series both of microwave radiometer brightness temperature measurements at 23.8 and 31.4 GHz and of retrievals of water vapor and liquid water path from these brightness temperatures are evaluated using the detrended fluctuation…

Atmospheric and Oceanic Physics · Physics 2009-11-07 K. Ivanova , E. E. Clothiaux , H. N. Shirer , T. P. Ackerman , J. C. Liljegren , M. Ausloos

Magnetic activity strongly impacts stellar RVs and the search for small planets. We showed previously that in the solar case it induces RV variations with an amplitude over the cycle on the order of 8 m/s, with signals on short and long…

Earth and Planetary Astrophysics · Physics 2017-11-08 N. Meunier , A. -M. Lagrange , S. Borgniet

High-frequency long-baseline experiments with the Atacama Large Millimeter/submillimeter Array were organized to test the high angular resolution imaging capabilities in the submillimeter wave regime using baselines up to 16 km. Four…

Ray tracing is a powerful tool that can be used to predict wireless channel characteristics, reducing the need for extensive channel measurements for channel characterization, evaluation of performance of sensing applications such as…

Information Theory · Computer Science 2023-02-27 O. Kanhere , T. S. Rappaport

The Multi-frequency Angular Power Spectrum (MAPS) is an alternative to spherically-averaged power spectra, and computes local fluctuations in the angular power spectrum without need for line-of-sight spectral transform. To test different…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-19 Cathryn M. Trott , Rajesh Mondal , Garrelt Mellema , Steven G. Murray , Bradley Greig , Jack L. B. Line , Nichole Barry , Miguel F. Morales

The Auger Engineering Radio Array (AERA) aims to detect extensive air showers caused by the interactions of ultra-high energy cosmic rays with the Earth's atmosphere, providing complementary information to the Auger surface, fluorescence…

Instrumentation and Methods for Astrophysics · Physics 2017-05-18 Qader Dorosti Hasankiadeh

The wide adoption of low-frequency radio interferometers as a tool for deeper and higher resolution astronomical observations has revolutionised radio astronomy. Despite their construction from static, relatively simple dipoles, the sheer…

Instrumentation and Methods for Astrophysics · Physics 2021-02-02 A. Chokshi , J. L. B. Line , N. Barry , D. Ung , D. Kenney , A. McPhail , A. Williams , R. L. Webster