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Title: A high-sensitivity push-pull magnetometer

Abstract

We describe our approach to atomic magnetometry based on the push-pull optical pumping technique. Cesium vapor is pumped and probed by a resonant laser beam whose circular polarization is modulated synchronously with the spin evolution dynamics induced by a static magnetic field. The magnetometer is operated in a phase-locked loop, and it has an intrinsic sensitivity below 20fT/√(Hz), using a room temperature paraffin-coated cell. We use the magnetometer to monitor magnetic field fluctuations with a sensitivity of 300fT/√(Hz)

Authors:
; ; ;  [1]
  1. Department of Physics, University of Fribourg, Fribourg 1700 (Switzerland)
Publication Date:
OSTI Identifier:
22275821
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CESIUM; LASERS; MAGNETIC FIELDS; MAGNETOMETERS; OPTICAL PUMPING; PARAFFIN; SENSITIVITY; SPIN; TEMPERATURE RANGE 0273-0400 K; VAPORS

Citation Formats

Breschi, E., Grujić, Z. D., Knowles, P., and Weis, A. A high-sensitivity push-pull magnetometer. United States: N. p., 2014. Web. doi:10.1063/1.4861458.
Breschi, E., Grujić, Z. D., Knowles, P., & Weis, A. A high-sensitivity push-pull magnetometer. United States. doi:10.1063/1.4861458.
Breschi, E., Grujić, Z. D., Knowles, P., and Weis, A. 2014. "A high-sensitivity push-pull magnetometer". United States. doi:10.1063/1.4861458.
@article{osti_22275821,
title = {A high-sensitivity push-pull magnetometer},
author = {Breschi, E. and Grujić, Z. D. and Knowles, P. and Weis, A.},
abstractNote = {We describe our approach to atomic magnetometry based on the push-pull optical pumping technique. Cesium vapor is pumped and probed by a resonant laser beam whose circular polarization is modulated synchronously with the spin evolution dynamics induced by a static magnetic field. The magnetometer is operated in a phase-locked loop, and it has an intrinsic sensitivity below 20fT/√(Hz), using a room temperature paraffin-coated cell. We use the magnetometer to monitor magnetic field fluctuations with a sensitivity of 300fT/√(Hz)},
doi = {10.1063/1.4861458},
journal = {Applied Physics Letters},
number = 2,
volume = 104,
place = {United States},
year = 2014,
month = 1
}
  • Path reversibility and radial symmetry are often assumed in push-pull tracer test analysis. In reality, heterogeneous flow fields mean that both assumptions are idealizations. In this paper, to understand their impact, we perform a parametric study which quantifies the scattering effects of ambient flow, local-scale dispersion, and velocity field heterogeneity on push-pull breakthrough curves and compares them to the effects of mobile-immobile mass transfer (MIMT) processes including sorption and diffusion into secondary porosity. We identify specific circumstances in which MIMT overwhelmingly determines the breakthrough curve, which may then be considered uninformative about drift and local-scale dispersion. Assuming path reversibility, wemore » develop a continuous-time-random-walk-based interpretation framework which is flow-field-agnostic and well suited to quantifying MIMT. Adopting this perspective, we show that the radial flow assumption is often harmless: to the extent that solute paths are reversible, the breakthrough curve is uninformative about velocity field heterogeneity. Our interpretation method determines a mapping function (i.e., subordinator) from travel time in the absence of MIMT to travel time in its presence. A mathematical theory allowing this function to be directly “plugged into” an existing Laplace-domain transport model to incorporate MIMT is presented and demonstrated. Algorithms implementing the calibration are presented and applied to interpretation of data from a push-pull test performed in a heterogeneous environment. A successful four-parameter fit is obtained, of comparable fidelity to one obtained using a million-node 3-D numerical model. In conclusion, we demonstrate analytically and numerically how push-pull tests quantifying MIMT are sensitive to remobilization, but not immobilization, kinetics.« less
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  • Intramolecular and intermolecular deuterium isotope effects have been measured for the thermal carbene H rearrangements of three substituted 1-phenyl-2-diazopropanes-1-d in hexane at 25/sup 0/C. The isotope effects, k/sub H//k/sub D/, vary from ca. 1.2 to 1.5, increasing with electron-withdrawing substituents, for the formation of both cis- and trans-..beta..-methylstyrenes. Product ratios were determined for these compounds as well as the corresponding undeuterated ones, permitting calculation of intermolecular primary and secondary isotope effects. In addition, the competition among the cis and trans products and the product of H migration from the terminal methyl group permitted determination of Hammett rho values of ca.more » -1 for the competition between benzylic and terminal migration. The results strongly indicate a ''pull-push'' mechanism, which can be pictured roughly as electrophilic attack on the C--H bond by the phantom p orbital of the carbene along with backside nucleophilic attack by the carbene unshared electron pair to push the H away and form the ..pi.. bond. The data are believed to be consistent only with a nonzero barrier for the carbene hydrogen rearrangement.« less