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We describe a new method which achieves high precision Very Long Baseline Interferometry (VLBI) astrometry in observations at millimeter wavelengths. It combines fast frequency-switching observations, to correct for the dominant…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 Maria J. Rioja , Richard Dodson

Atom interferometry is a powerful experimental technique that can be employed to search for the oscillation of atomic transition energies induced by ultralight scalar dark matter (ULDM). Previous studies have focused on the sensitivity to…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-01 Leonardo Badurina , Diego Blas , Christopher McCabe

A general solution for the electrostatic potential in an atomic-thin-body (ATB) field-effect transistor geometry is presented. The effective electrostatic scaling length, {\lambda}eff, is extracted from the analytical model, which cannot be…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 Qin Zhang , Yeqing Lu , Huili Grace Xing , Steven J. Koester , Siyuranga O. Koswatta

We present results from observation, correlation and analysis of interferometric measurements between the three geodetic very long baseline interferometry (VLBI) stations at the Onsala Space Observatory. In total 25 sessions were observed…

Instrumentation and Methods for Astrophysics · Physics 2021-05-05 Eskil Varenius , Rüdiger Haas , Tobias Nilsson

We have used the Very Long Baseline Array (VLBA) at 43, 23 and 15 GHz to measure the solar gravitational deflection of radio waves among four radio sources during an 18-day period in October 2005. Using phase-referenced radio interferometry…

Cosmology and Nongalactic Astrophysics · Physics 2009-07-22 E. Fomalont , S. Kopeikin , G. Lanyi , J. Benson

High precision astrometric Space Very Long Baseline Interferometry (S-VLBI) at the low end of the conventional frequency range, i.e. 20cm, is a requirement for a number of high priority science goals. These are headlined by obtaining…

Instrumentation and Methods for Astrophysics · Physics 2015-06-15 R. Dodson , M. Rioja , Y. Asaki , H. Imai , X. -Y. Hong , Z. Shen

The observation and imaging of hundreds or thousands of radio sources with the technique of very long baseline interferometry (VLBI) is a computationally intensive task. However, these surveys allow us to conduct statistical investigations…

Astrophysics of Galaxies · Physics 2017-06-28 Kristóf Rozgonyi , Sándor Frey

Extension of very long baseline interferometry (VLBI) to observing wavelengths shorter than 1.3mm provides exceptional angular resolution (~20 micro arcsec) and access to new spectral regimes for the study of astrophysical phenomena. To…

Instrumentation and Methods for Astrophysics · Physics 2011-06-02 Sheperd Doeleman , Tao Mai , Alan Rogers , John Hartnett , Michael Tobar , Nitin Nand

We present a magnetically shielded environment with a damping factor larger than one million at the mHz frequency regime and an extremely low field and gradient over an extended volume. This extraordinary shielding performance represents an…

Millimeter-VLBI images probe as deep as never before the nuclei of AGN. Global 3mm-VLBI where the VLBA is combined with sensitive European stations, gives CLEAN maps of a quality, which never before was so good. VLBI at 147 GHz yields…

Astrophysics · Physics 2007-05-23 T. P. Krichbaum , D. A. Graham , A. Witzel , J. A. Zensus , A. Greve , H. Ungerechts , M. Grewing

We report on a single-channel rubidium radio-frequency atomic magnetometer operating in un-shielded environments and near room temperature with a measured sensitivity of 130 fT/\sqrt{Hz}. We demonstrate consistent, narrow-bandwidth…

Atomic Physics · Physics 2018-08-27 Cameron Deans , Luca Marmugi , Ferruccio Renzoni

We study a novel millimetre-scale magnetic trap for ultracold atoms, in which the current carrying conductors can be situated outside the vacuum region, a few mm away from the atoms. This design generates a magnetic field gradient in excess…

The Caltech-Jodrell Bank very long baseline interferometry (VLBI) Surveys give detailed 5 GHz VLBI images of several hundred milliarcsecond (mas) radio sources, and the full width at half-maximum angular sizes of the corresponding compact…

Astrophysics · Physics 2009-11-13 J. C. Jackson

In this paper we introduce a software package, the Very Long Baseline Interferometry Network SIMulator (VNSIM), which provides an integrated platform assisting radio astronomers to design the Very Long Baseline Interferometry (VLBI)…

Instrumentation and Methods for Astrophysics · Physics 2019-11-11 Zhen Zhao , Tao An , Baoqiang Lao

We present a new method of time-dependent instrumental polarization calibration for Very Long Baseline Interferometry (VLBI). This method has been implemented in the recently developed polarization calibration pipeline GPCAL. Instrumental…

Instrumentation and Methods for Astrophysics · Physics 2023-10-06 Jongho Park , Keiichi Asada , Do-Young Byun

Extension of radio interferometric baselines into space is inevitable if a diffraction-limited angular resolution defined by the Earth diameter at a given observing wavelength limits a pursuit of specific scientific goals. This was…

Instrumentation and Methods for Astrophysics · Physics 2018-10-03 Leonid I. Gurvits

In this paper we describe a new approach for mm-VLBI calibration that provides bona-fide astrometric alignment of the mm-wavelength images from a single source, for the measurement of frequency dependent effects, such as `core-shifts' near…

Instrumentation and Methods for Astrophysics · Physics 2017-01-18 Richard Dodson , María Rioja , Sol Molina , José-Luis Gómez

Very Long Baseline Interferometry (VLBI) astrometry is a well established technique for achieving $\pm10~\mu$as parallax accuracies at frequencies well above 10~GHz. At lower frequencies, uncompensated interferometer delays associated with…

Instrumentation and Methods for Astrophysics · Physics 2023-02-15 Lucas J. Hyland , Mark J. Reid , Simon P. Ellingsen , Maria J. Rioja , Richard Dodson , Gabor Orosz , Colin R. Masson , Jamie M. McCallum

We report on the development of a microfabricated atomic magnetic gradiometer based on optical spectroscopy of alkali atoms in the vapor phase. The gradiometer, which operates in the spin-exchange relaxation free regime, has a length of 60…

Instrumentation and Detectors · Physics 2017-02-14 Dong Sheng , Abigail R. Perry , Sean P. Krzyzewski , Shawn Geller , John Kitching , Svenja Knappe

We consider the matterwave interferometric measurement of atomic velocities, which forms a building block for all matterwave inertial measurements. A theoretical analysis, addressing both the laboratory and atomic frames and accounting for…

Atomic Physics · Physics 2018-02-14 Max Carey , Mohammad Belal , Matthew Himsworth , James Bateman , Tim Freegarde