Elwin Dijck

A new approach to test Lorentz invariance

Lorentz invariance in the weak interaction has been tested rather poorly compared to the electromagnetic interaction. In this work we show which tests on the weak interaction should be considered. We focus on one particular test that explores the spin degree of freedom in {\beta} decay. To connect various phenomenological tests of Lorentz invariance in the weak interaction, we exploit a new theoretical model that may provide a framework that relates the different tests.

First Test of Lorentz Invariance in the Weak Decay of Polarized Nuclei

A new test of Lorentz invariance in the weak interactions has been made by searching for variations in the decay rate of spin-polarized Na-20 nuclei. This test is unique to Gamow-Teller transitions, as was shown in the framework of a recently developed theory that assumes a Lorentz symmetry breaking background field of tensor nature. The nuclear spins were polarized in the up and down direction, putting a limit on the amplitude of sidereal variations of the form vertical bar(Gamma(up) - Gamma(down))vertical bar/(Gamma(up) + Gamma(down)) <3 x 10(-3). This measurement shows a possible route toward a more detailed testing of Lorentz symmetry in weak interactions.

A new approach to test Lorentz invariance in the weak interaction

Lorentz invariance in the weak interaction has been tested rather poorly compared to the electromagnetic interaction. In this work we show which tests on the weak interaction should be considered. We focus on one particular test that explores the spin degree of freedom in {\beta} decay. To connect various phenomenological tests of Lorentz invariance in the weak interaction, we exploit a new theoretical model that may provide a framework that relates the different tests.

Determination of transition frequencies in a single Ba-138(+) ion

Transition frequencies between low-lying energy levels in a single trapped Ba-138(+) ion have been measured with laser spectroscopy referenced to an optical frequency comb. By extracting the frequencies of one-photon and two-photon components of the line shape using an eight-level optical Bloch model, we achieved 0.1 MHz accuracy for the 5d D-2(3/2)-6p P-2(1/2) and 6s S-2(1/2)-5d D-2(3/2) transition frequencies, and 0.2MHz for the 6s S-2(1/2)-6p P-2(1/2) transition frequency.

Effect of soil temperature on optical frequency transfer through unidirectional dense-wavelength-division-multiplexing fiber-optic links

Results of optical frequency transfer over a carrier-grade dense-wavelength-division-multiplexing (DWDM) optical fiber network are presented. The relation between soil temperature changes on a buried optical fiber and frequency changes of an optical carrier through the fiber is modeled. Soil temperatures, measured at various depths by the Royal Netherlands Meteorology Institute (KNMI) are compared with observed frequency variations through this model. A comparison of a nine-day record of optical frequency measurements through the 2×298  km fiber link with soil temperature data shows qualitative agreement. A soil temperature model is used to predict the link stability over longer periods (days-months-years). We show that optical frequency dissemination is sufficiently stable to distribute and compare, e.g., rubidium frequency standards over standard DWDM optical fiber networks using unidirectional fibers.

A gas cell for stopping, storing and polarizing radioactive particles

A radioactive beam of Na-20 is stopped in a gas cell filled with Ne gas. The stopped particles are polarized by optical pumping. The degree of polarization that can be achieved is studied. A maximum polarization of 50% was found. The dynamic processes in the cell are described with a phenomenological model

Precision Tests of Discrete Symmetries at Low Energies

Low energy precision measurements provide for precise testing of the Standard Model, e.g., in searches for violations of the discrete symmetries charge conjugation (C), parity (P), and time reversal (T) as well as their combinations CP and CPT. We focus here on new experiments concerning atomic parity violation (APV) and searches for a permanent electric dipole moment (EDM) in atoms. In particular, we address precision APV experiments on Ba+ and Ra+ single ions that will enable the extraction of the Weinberg angle at lowest presently accessible momentum transfer. They are expected to contribute towards searches for new particles such as dark Z-bosons. We also review experimental programmes in which an EDM is searched for and we compare them in a common framework. We describe latest EDM searches in heavy effective two-electron atoms such as Xe and Hg. We also indicate possible future prospects of searches for a permanent EDM of the electron using molecules with large enhancement factors.

Test of Lorentz invariance in β decay of polarized Na-20

We search for a dependence of the lifetime of

Test of Lorentz invariance in

^{20}\text{Na}

\beta

nuclei on the nuclear spin direction. Such a directional dependence would be evidence for Lorentz-invariance violation in weak interactions. A difference in lifetime between nuclei that are polarized in the east and west direction is searched for. This difference is maximally sensitive to the rotation of the Earth, while the sidereal dependence is free from most systematic errors. The experiment sets a limit of