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8 results on '"Weyers S"'

1. Apparent power-dependent frequency shift due to collisions in a cesium fountain.

Author

Szymaniec K, Chalupczak W, Weyers S, and Wynands R

Subjects
Computer Simulation, Half-Life, Cesium chemistry, Energy Transfer, Microwaves, Models, Theoretical, Oscillometry methods, Time Factors
Abstract

We describe a situation where a varying collisional frequency shift in cesium fountain primary frequency standards can be misinterpreted as a power-dependent shift. This misinterpretation may affect analyses of fountains test-operated at multiple pi/2 microwave pulse areas. Such tests are typically performed in the search for microwave- and cavity-related systematic frequency biases.

Published
2007
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3. THE ATOMIC CAESIUM FOUNTAIN CSF1 OF PTB.

Author

WEYERS, S., BAUCH, A., SCHRÖDER, R., and TAMM, CHR.

Subjects
CESIUM, ATOMIC frequency standards, QUADRUPOLES, MICROWAVES, UNCERTAINTY
Published
2002

4. TEMPERATURE OF CESIUM ATOMS IN GRAY OPTICAL MOLASSES.

Author

BOIRON, D., MICHAUD, A., LEMONDE, P., SALOMON, C., WEYERS, S., SZYMANIEC, K., and CLAIRON, A.

Subjects
CESIUM, OPTICAL modulation, LASER cooling, MAGNETOOPTICAL trapping, QUANTUM states, PHOTON emission
Published
1996

6. Improved Limit on a Temporal Variation of mp/me from Comparisons of Yb+ and Cs Atomic Clocks.

Author

Huntemann, N., Lipphardt, B., Tamm, Chr., Gerginov, V., Weyers, S., and Peik, E.

Subjects
*IONIZATION constants, *SPECTROMETRY, *PROTONS, *ELECTRONS, *CESIUM
Abstract

Accurate measurements of different transition frequencies between atomic levels of the electronic and hyperfine structure over time are used to investigate temporal variations of the fine structure constant a and the proton-to-electron mass ratio fi. We measure the frequency of the 2 Si/2 ->2 Ft/2 electric octupole (?3) transition in 171 Yb+ against two caesium fountain clocks as /(? 3 ) = 642 121 496772645.36 Hz with an improved fractional uncertainty of 3.9 x 10~16. This transition frequency shows a strong sensitivity to changes of a. Together with a number of previous and recent measurements of the 2Si/2 -?? 2D2/2 electric quadrupole transition in 171Yb+ and with data from other elements, a least-squares analysis yields (1 /a)(da/dt) = -0.20(20) x 10-16/y r and (l//i)(dfi/dt) = -0.5(1.6) x 10~16/yr, confirming a previous limit on da/dt and providing the most stringent limit on dji/dt from laboratory experiments. [ABSTRACT FROM AUTHOR]

Published
2014
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7. Cs-based optical frequency measurement using cross-linked optical and microwave oscillators.

Author

Huntemann, Chr. Tamm, N., Lipphardt, B., Gerginov, V., Nemitz, N., Kazda, M., Weyers, S., and Peik, E.

Subjects
*OPTICAL frequency conversion, *WAVELENGTHS, *MICROWAVE oscillators, *CESIUM, *PHASE transitions, *FIBER lasers, *TEMPERATURE effect
Abstract

We describe a measurement of the frequency of the ²S1/2(F = 0)-²D3/2(F' = 2) transition of 171 Yb+ at the wavelength 436 nm (frequency 688 THz), using a single Yb+ ion confined in a Paul trap and two cesium fountains as references. In one of the fountains, the frequency of the microwave oscillator that interrogates the cesium atoms is stabilized by the laser that excites the Yb+ reference transition with a linewidth in the hertz range. The stability is transferred to the microwave oscillator with the use of a fiber laser-based optical frequency comb generator that also provides the frequency conversion for the absolute frequency measurement. The frequency comb generator is configured as a transfer oscillator so that fluctuations of the pulse repetition rate and of the carrier offset frequency do not degrade the stability of the frequency conversion. The phase noise level of the generated ultrastable microwave signal is comparable to that of a cryogenic sapphire oscillator. For fountain operation with optical molasses loaded from a laser-cooled atomic beam source, we obtain a stability corresponding to a fractional Allan deviation of 4.1 x 10-14 (r/s)-l/2. With the molasses loaded from thermal vapor and an averaging time of 65 h, we measure the frequency of the Yb+ transition with a relative statistical uncertainty of 2.8 x 10-16 and a systematic uncertainty of 5.9 x 10-16. The frequency was also simultaneously measured with the second fountain that uses a quartz-based interrogation oscillator. The unperturbed frequency of the Yb+ transition is realized with an uncertainty of 1.1 x 10-16 that mainly results from the uncertainty of the blackbody shift at the operating temperature near 300 K. The transition frequency of 688 358 979 309 307.82(36) Hz, measured with the two fountains, is in good agreement with previous results. [ABSTRACT FROM AUTHOR]

Published
2014
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8. Improved Limits for Violations of Local Position Invariance from Atomic Clock Comparisons.

Author

Lange, R., Huntemann, N., Rahm, J. M., Sanner, C., Shao, H., Lipphardt, B., Tamm, Chr., Weyers, S., and Peik, E.

Subjects
*ATOMIC clocks, *FINE-structure constant, *GRAVITATIONAL potential, *COUPLING constants, *MAGNITUDE (Mathematics), *CESIUM
Abstract

We compare two optical clocks based on the ²S1/2(F=0)→²D3/2(F=2) electric quadrupole (E2) and the 2S1/2(F=0)→²F7/2(F=3) electric octupole (E3) transition of 171Yb+ and measure the frequency ratio νE3/νE2=0.932829404530965376(32), improving upon previous measurements by an order of magnitude. Using two caesium fountain clocks, we find νE3=642121496772645.10(8)  Hz, the most accurate determination of an optical transition frequency to date. Repeated measurements of both quantities over several years are analyzed for potential violations of local position invariance. We improve by factors of about 20 and 2 the limits for fractional temporal variations of the fine structure constant α to 1.0(1.1)×10-18/yr and of the proton-to-electron mass ratio μ to -8(36)×10-18/yr. Using the annual variation of the Sun's gravitational potential at Earth Φ, we improve limits for a potential coupling of both constants to gravity, (c²/α)(dα/dΦ)=14(11)×10-9 and (c²/μ)(dμ/dΦ)=7(45)×10-8. [ABSTRACT FROM AUTHOR]

Published
2021
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