Showing papers by "Nathal Severijns published in 2021"
TL;DR: In this article, the authors obtained lower bounds on the oscillation time of a neutral standard model particle such as the neutron and its mirror counterpart, assuming nonzero mirror magnetic fields, where β is the fixed angle between the applied magnetic field and the local mirror magnetic field.
34 citations
ETH Zurich1, University of Caen Lower Normandy2, Katholieke Universiteit Leuven3, Paul Scherrer Institute4, Jagiellonian University5, University of Grenoble6, University of Bern7, University of Kentucky8, University of Mainz9, University of Sussex10, University of Belgrade11, Fraunhofer Society12, German National Metrology Institute13
TL;DR: In this paper, the authors present the design of a next-generation experiment, n2EDM, currently under construction at the ultracold neutron source at the Paul Scherrer Institute (PSI) with the aim of carrying out a high-precision search for an electric dipole moment of the neutron.
Abstract: We present the design of a next-generation experiment, n2EDM, currently under construction at the ultracold neutron source at the Paul Scherrer Institute (PSI) with the aim of carrying out a high-precision search for an electric dipole moment of the neutron. The project builds on experience gained with the previous apparatus operated at PSI until 2017, and is expected to deliver an order of magnitude better sensitivity with provision for further substantial improvements. An overview is of the experimental method and setup is given, the sensitivity requirements for the apparatus are derived, and its technical design is described.
11 citations
Posted Content•
TL;DR: In this article, the authors present the results of these campaigns, and the improvement the correction of this effect brings to the neutron electric dipole moment measurement, and evaluate and correct that effect, offline measurements of the field nonuniformity were performed during mapping campaigns in 2013, 2014 and 2017.
Abstract: Experiments dedicated to the measurement of the electric dipole moment of the neutron require outstanding control of the magnetic field uniformity. The neutron electric dipole moment (nEDM) experiment at the Paul Scherrer Institute uses a 199Hg co-magnetometer to precisely monitor magnetic field variations. This co-magnetometer, in the presence of field non-uniformity, is responsible for the largest systematic effect of this measurement. To evaluate and correct that effect, offline measurements of the field non-uniformity were performed during mapping campaigns in 2013, 2014 and 2017. We present the results of these campaigns, and the improvement the correction of this effect brings to the neutron electric dipole moment measurement.
3 citations
ETH Zurich1, University of Caen Lower Normandy2, Katholieke Universiteit Leuven3, Paul Scherrer Institute4, Jagiellonian University5, University of Grenoble6, University of Bern7, University of Kentucky8, University of Mainz9, University of Sussex10, University of Belgrade11, German National Metrology Institute12
TL;DR: In this paper, the authors present the design of a next-generation experiment, n2EDM, currently under construction at the ultracold neutron source at the Paul Scherrer Institute (PSI) with the aim of carrying out a high-precision search for an electric dipole moment of the neutron.
Abstract: We present the design of a next-generation experiment, n2EDM, currently under construction at the ultracold neutron source at the Paul Scherrer Institute (PSI) with the aim of carrying out a high-precision search for an electric dipole moment of the neutron The project builds on experience gained with the previous apparatus operated at PSI until 2017, and is expected to deliver an order of magnitude better sensitivity with provision for further substantial improvements An overview is given of the experimental method and setup, the sensitivity requirements for the apparatus are derived, and its technical design is described
Posted Content•
TL;DR: In this article, an overview of current experimental and theoretical knowledge of the most important recoil term, weak magnetism, for both the $T = 1/2$ mirror and a large set of nuclear β-decays in higher isospin multiplets is presented.
Abstract: In recent years a number of correlation measurements in nuclear $\beta$ decay have been performed reaching a precision of the order of 1% and below and it is expected that even higher precision will be reached in the near future. At these levels of precision higher-order corrections due to e.g. recoil terms induced by the strong interaction and radiative corrections cannot necessarily be neglected anymore when interpreting these results in terms of new physics or extracting a value for the $V_{ud}$ quark-mixing matrix element. We provide here an update of the $\mathcal{F} t$ values of the $T=1/2$ mirror $\beta$ decays as well as an overview of current experimental and theoretical knowledge of the most important recoil term, weak magnetism, for both the $T=1/2$ mirror $\beta$ transitions and a large set of $\beta$ decays in higher isospin multiplets. The matrix elements determining weak magnetism were calculated in the nuclear shell model and cross-checked against experimental data, showing overall good agreement. Additionally, we show that further insight can be obtained from properly deformed nuclear potentials, in particular for mirror $T=1/2$ decays.. The results provide new insights in the size of weak magnetism, extending the available information to $\beta$ transitions of nuclei with masses up to $A =$ 75. This provides important guidance for the planning and interpretation of ongoing and new precise correlation measurements in nuclear $\beta$ decay searching for new physics or to extract the $V_{ud}$ quark-mixing matrix element in mirror $\beta$ decays. This more detailed knowledge of weak magnetism can also be of interest for further theoretical work related to the reactor neutrino problem.
TL;DR: In this article, the surface and volume-averaged root-mean-square normal noise amplitudes at a certain frequency bandwidth for a cylindrical geometry were derived for a large-scale long-measurement time experiment with the implementation of a comagnetometry.
Abstract: Magnetic Johnson-Nyquist noise (JNN) originating from metal electrodes, used to create a static electric field in neutron electric-dipole-moment (nEDM) experiments, may limit the sensitivity of measurements. We present here a dedicated study on JNN applied to a large-scale long-measurement-time experiment with the implementation of a comagnetometry. In this study, we derive surface- and volume-averaged root-mean-square normal noise amplitudes at a certain frequency bandwidth for a cylindrical geometry. In addition, we model the source of noise as a finite number of current dipoles and demonstrate a method to simulate temporal and three-dimensional spatial dependencies of JNN. The calculations are applied to estimate the impact of JNN on measurements with the new apparatus, n2EDM, at the Paul Scherrer Institute. We demonstrate that the performances of the optically pumped Cs133 magnetometers and Hg199 comagnetometers, which will be used in the apparatus, are not limited by JNN. Further, we find that, in measurements deploying a comagnetometer system, the impact of JNN is negligible for nEDM searches down to a sensitivity of 4×10-28ecm in a single measurement; therefore, the use of economically and mechanically favored solid aluminum electrodes is possible.
TL;DR: In this article, the authors present a current-monitoring system based on optical magnetometry, which is able to discriminate true current variations from environmental effects at room temperature, using a dedicated thermally stable magnetic-field-confining coil and an array of four optically pumped magnetometers arranged in a two-dimensional gradiometer configuration.
Abstract: We present a current-monitoring system based on optical magnetometry, which is able to discriminate true current variations from environmental effects at room temperature. The system consists of a dedicated thermally stable magnetic-field-confining coil and an array of four optically pumped magnetometers arranged in a two-dimensional gradiometer configuration. These magnetometers monitor magnetic field variations inside the coil, which correlate with the variations of the driving current of the coil. The system uses a digital signal-processing unit to extract and record in real time the magnetic field values measured by the magnetometers, which allows real-time monitoring of the current. The coil of the system, which is made out of printed circuit boards, can easily be changed to adapt the current-to-field conversion. Thus, we can expand the applicability of this system to a wide range of currents. By using this system to actively feedback control a current source, we stabilize a current of 20 mA on a level better than $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ for an integration time of 70 min.