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20 results on '"Fayer, S. E."'

1. Switchable Damping for a One-Particle Oscillator

Author

Fan, X., Fayer, S. E., Myers, T. G., Sukra, B. A. D., Nahal, G., and Gabrielse, G.

Subjects
Quantum Physics, High Energy Physics - Experiment, Physics - Atomic Physics, Physics - Instrumentation and Detectors
Abstract

The possibility to switch the damping rate for a one-electron oscillator is demonstrated, for an electron that oscillates along the magnetic field axis in a Penning trap. Strong axial damping can be switched on to allow this oscillation to be used for quantum nondemolition detection of the cyclotron and spin quantum state of the electron. Weak axial damping can be switched on to circumvent the backaction of the detection motion that has limited past measurements. The newly developed switch will reduce the linewidth of the cyclotron transition of one-electron by two orders of magnitude., Comment: 8 pages, 7 figures

Published
2020
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2. Towards an Improved Test of the Standard Model's Most Precise Prediction

Author

Gabrielse, G., Fayer, S. E., Myers, T. G., and Fan, X.

Subjects
Quantum Physics, Physics - Instrumentation and Detectors
Abstract

The electron and positron magnetic moments are the most precise prediction of the standard model of particle physics. The most accurate measurement of a property of an elementary particle has been made to test this result. A new experimental method is now being employed in an attempt to improve the measurement accuracy by an order of magnitude. Positrons from a "student source" now suffice for the experiment. Progress toward a new measurement is summarized.

Published
2019

3. Gaseous $^3$He Nuclear Magnetic Resonance Probe for Cryogenic Environments

Author

Fan, X., Fayer, S. E., and Gabrielse, G.

Subjects
Physics - Atomic Physics, Physics - Instrumentation and Detectors
Abstract

Normal nuclear magnetic resonance (NMR) probes cannot be used to make high frequency resolution measurements in a cryogenic environment because they lose their frequency resolution when the liquid sample in the probe freezes. A gaseous $^3$He NMR probe, designed and constructed to work naturally in such cryogenic environments, is demonstrated at 4.2 K and 5.3 Tesla to have a frequency resolution better than 0.4 part per billion. As a demonstration of its usefulness, the cryogenic probe is used to shim a superconducting solenoid with a cryogenic interior to produce a magnetic field with a high spatial homogeneity, and to measure the magnetic field stability., Comment: 9 pages, 11 figures

Published
2019
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4. Interactions of positrons & positronium with matter

Author

Fayer, S. E.

Subjects
539.7
Abstract

The aim of this work is to help and advance the understanding of the interaction of positrons and positronium (Ps) with matter. Knowledge of these interactions has a wide range of applications in many fields including medical imaging, galactic astronomy and condensed matter physics. An electrostatic beam of positrons has been used with a tungsten mesh moderator and a tungsten foil remoderator. The beam has been characterised to have a beam divergence of ∼ 1 degree and energy resolution of 1%. The system has been applied to the measurements of the positron total cross section for He. Despite improved absolute angular resolution and a truly field-free interaction region, similarity with previous magnetic beam measurements with poorer angular resolution and theories has been found, in contrast with the only previous electrostatic beam measurements. The collimated Ps production efficiency from Ar and Xe has been measured down to 1.4eV, enabling Ps scattering experiments to be performed in a new energy range. The total cross sections for Ps scattering from Ar, Xe, O2 and CF4 have been measured between 1.4 and 120eV. In comparison with the total cross section for equivelocity electrons, an enhancement in the Ps scattering is observed centred at ∼ 5 eV. For Ar and Xe, in contrast to theoretical predictions, the Ps total cross section is found to be not inconsistent with the Ramsauer-Townsend minima for electrons. The absolute differential Ps formation cross section near 0 degrees has been determined for Ar, Kr and Xe and compared with theory. In analogy with a semi-empirical scaling previously found for the integral Ps formation cross section, similarities in shape of the scaled differential Ps formation cross sections have been found between Ar, Kr and Xe and, separately, from those of He and H2 . An exponential relationship has been found between the maximum differential Ps formation cross section and the Ps formation threshold.

Published
2016

5. Low-energy positronium scattering from O2

Author

Newson, D. M., primary, Kadokura, R., additional, Allen, H., additional, Fayer, S. E., additional, Brawley, S. J., additional, Shipman, M., additional, Laricchia, G., additional, Wilde, R. S., additional, Fabrikant, I. I., additional, and Sarkadi, L., additional

Published
2023
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9. Moderation and diffusion of positrons in tungsten meshes and foils.

Author

Williams, A. I., Murtagh, D. J., Fayer, S. E., Andersen, S. L., Chevallier, J., Kövér, Á., Van Reeth, P., Humberston, J. W., and Laricchia, G.

Subjects
TUNGSTEN alloys, POSITRONS, MESH analysis (Electric circuits), METAL foils, THICKNESS measurement
Abstract

The efficiency of tungsten meshes and thin foils for moderation of fast positrons from 22 Na has been investigated in transmission geometry and a fair agreement has been found with previous experimental results where directly comparable. For foils, the dependence on material thickness is found to be similar to the prediction of the Vehanen-Mäkinen diffusion model; however, the magnitude is 5-10 times lower. A broad consensus is observed between experiment and the results of a three-dimensional model developed in this work. For a given thickness, meshes are found to be generally better than foils by around a factor of 10 with a maximum efficiency (~10-3) comparable to that achieved with thin single crystal foils, in accord with previous measurements and the results of the present model. [ABSTRACT FROM AUTHOR]

Published
2015
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13. Gaseous 3He nuclear magnetic resonance probe for cryogenic environments.

Author

Fan, X., Fayer, S. E., and Gabrielse, G.

Subjects
*NUCLEAR magnetic resonance, *NUCLEAR magnetic resonance spectroscopy, *MAGNETIC fields
Abstract

Normal nuclear magnetic resonance (NMR) probes cannot be used to make high frequency resolution measurements in a cryogenic environment because they lose their frequency resolution when the liquid sample in the probe freezes. A gaseous 3He NMR probe, designed and constructed to work naturally in such cryogenic environments, is demonstrated at 4.2 K and 5.3 T to have a frequency resolution better than 0.4 ppb. As a demonstration of its usefulness, the cryogenic probe is used to shim a superconducting solenoid with a cryogenic interior to produce a magnetic field with a high spatial homogeneity and to measure the magnetic field stability. [ABSTRACT FROM AUTHOR]

Published
2019
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20. High-Resolution Measurements of e+ + H2O Total Cross Section.

Author

Loreti, A., Kadokura, R., Fayer, S. E., Kövér, Á., and Laricchia, G.

Subjects
*POSITRON beams, *SCATTERING (Physics)
Abstract

Using a purely electrostatic positron beam, the total cross section of positrons scattering from H2O has been measured for the first time with a high angular discrimination (≃ 1°) against forward scattered projectiles. Results are presented in the energy range (10-300) eV. Significant deviations from previous measurements are found which are, if ascribed entirely to the angular acceptances of various experimental systems, in quantitative accord with ab initio theoretical predictions of the differential elastic scattering cross section. [ABSTRACT FROM AUTHOR]

Published
2016
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