Showing papers by "Nathal Severijns published in 2017"
TL;DR: In this article, the axion-wind spin-precession frequencies of stored ultracold neutrons and 199Hg atoms were analyzed for axion induced oscillating electric dipole moment of the neutron and an axion wind spin precession effect.
Abstract: We report on a search for ultra-low-mass axion-like dark matter by analysing the ratio of the spinprecession frequencies of stored ultracold neutrons and 199Hg atoms for an axion-induced oscillating electric dipole moment of the neutron and an axion-wind spin-precession effect. No signal consistent with dark matter is observed for the axion mass range 1024 eV ma 10 17 eV. Our null result sets the first laboratory constraints on the coupling of axion dark matter to gluons, which improve on astrophysical limits by up to 3 orders of magnitude, and also improves on previous laboratory constraints on the axion coupling to nucleons by up to a factor of 40.
172 citations
TL;DR: In this paper, the axion-wind spin-precession frequencies of stored ultracold neutrons and $199$Hg atoms for an axion induced oscillating electric dipole moment of the neutron and axion wind spin precession effect were analyzed.
Abstract: We report on a search for ultra-low-mass axion-like dark matter by analysing the ratio of the spin-precession frequencies of stored ultracold neutrons and $^{199}$Hg atoms for an axion-induced oscillating electric dipole moment of the neutron and an axion-wind spin-precession effect. No signal consistent with dark matter is observed for the axion mass range $10^{-24}~\textrm{eV} \le m_a \le 10^{-17}~\textrm{eV}$. Our null result sets the first laboratory constraints on the coupling of axion dark matter to gluons, which improve on astrophysical limits by up to 3 orders of magnitude, and also improves on previous laboratory constraints on the axion coupling to nucleons by up to a factor of 40.
95 citations
TL;DR: In this article, different aspects of the weak interaction have been studied at ISOLDE, ranging from half-lives, branching ratios and nuclear masses relevant for the determination of the V ( )ud( ) quark-mixing matrix element, over β-asymmetry and β-nu$ correlation measurements searching for possible tensor and/or scalar contributions to the weak interactions.
Abstract: Radioactive nuclei offer unique possibilities to study the structure and symmetries of the weak interaction in nuclear β decay. The large variety of nuclear states available allows selecting the ones that are best suited to study the phenomena of interest with optimal sensitivity, while at the same time minimising the effects of nuclear structure. The ISOLDE facility, offering worldwide the largest variety and intensity of radioactive beams, is one of the best suited laboratories in this respect. Over the last decade or so different aspects of the weak interaction have been studied at ISOLDE, ranging from half-lives, branching ratios and nuclear masses relevant for the determination of the V ( )ud( ) quark-mixing matrix element, over β-asymmetry and $\beta
u $ correlation measurements searching for possible tensor and/or scalar contributions to the weak interaction, up to a measurement showing the effect of parity violation in the weak interaction in gamma decay. In addition, new projects respectively searching for scalar currents in the β-delayed proton decay of (32)Ar, or to determine the V ( )ud( ) quark-mixing matrix element from the β-asymmetry parameter in the mirror decay of (35)Ar, have just started.
10 citations
TL;DR: In this paper, a magnetic field confining coil with sub-10−3 field uniformity over a large fraction of the coil is presented for an atomic magnetometry-based current controller.
Abstract: We present a magnetic field confining coil with a sub-10−3 field uniformity over a large fraction of the coil. The structure is entirely made out of printed circuit boards (PCBs). The PCB design allows the path of the wires to be tailored to fit the required geometry. We measure the field uniformity with cesium magnetometers in a field range from 1 to 10 µT. Our application uses such a coil for an atomic magnetometry-based current controller.
10 citations
TL;DR: In this paper, a new laser spin-polarization setup has been installed at the ISOLDE facility at CERN, which is located at the VITO beamline which aims to bring together several experimental techniques using polarized ions allowing for studies in nuclear physics, fundamental interactions, material and life sciences.
Abstract: Following a growing interest in spin-polarized beams of radioactive ions, a new laser spin-polarization setup has been installed at the ISOLDE facility at CERN. The setup is located at the VITO beamline which aims to bring together several experimental techniques using polarized ions allowing for studies in nuclear physics, fundamental interactions, material and life sciences. Intensive design work, which took place in 2016, allowed the installation of the first stage of the polarization line. With this experimental setup, the ion beam can be neutralized, polarized and implanted into a solid sample inside an electromagnet which also hosts β-detectors, where the degree of nuclear spin polarization can be measured. In autumn 2016 the setup was commissioned using short-lived 26Na and 28Na beams which were polarized in the D2 line from their atomic ground state. The previously observed degrees of β asymmetry were reproduced and thus the beamline is now ready for the first physics experiments with spin-polarized radioactive beams.
10 citations
TL;DR: In this paper, an analytic solution to the magnetostatic inverse problem in the framework of vector spherical harmonic basis functions is presented for the design of a spherical magnetic field compensation system and its performance is compared with an already existing rectangular coil system.
Abstract: An analytic solution to the magnetostatic inverse problem in the framework of vector spherical harmonic basis functions is presented. This formalism is used for the design of a spherical magnetic field compensation system and its performance is compared with an already existing rectangular coil system. The proposed set of spherical coils with 15 degrees of freedom achieves a shielding factor of 1000 or better in a large part of the volume enclosed by the coils for a dipolar type external perturbation.
7 citations
TL;DR: In this paper, a high-precision half-life measurement for the superallowed (n = 1/2) = 22.4506(33) s was performed at the TRIUMF-ISAC radioactive ion beam facility yielding a result that is a factor of 4 more precise than the previous world-average halflife for mirror nuclei.
Abstract: A high-precision half-life measurement for the superallowed ${\ensuremath{\beta}}^{+}$ transition between the isospin $T=1/2$ mirror nuclei $^{21}\mathrm{Na}$ and $^{21}\mathrm{Ne}$ has been performed at the TRIUMF-ISAC radioactive ion beam facility yielding ${T}_{1/2}=22.4506(33)$ s, a result that is a factor of 4 more precise than the previous world-average half-life for $^{21}\mathrm{Na}$ and represents the single most precisely determined half-life for a transition between mirror nuclei to date. The contribution to the uncertainty in the $^{21}\mathrm{Na} \mathcal{F}{t}^{\mathrm{mirror}}$ value due to the half-life is now reduced to the level of the nuclear-structure-dependent theoretical corrections, leaving the branching ratio as the dominant experimental uncertainty.
3 citations
TL;DR: In this paper, a magnetic field confining coil with a sub-10−3$ field uniformity over a large fraction of the coil is presented, which allows to tailor the path of wires to fit the required geometry.
Abstract: We present a magnetic field confining coil with a sub-$10^{-3}$ field uniformity over a large fraction of the coil. The structure is entirely made out of printed circuit boards (PCBs). The PCB design allows to tailor the path of wires to fit the required geometry. We measure the field uniformity with cesium magnetometers in a field range from 1 to 10 $\mu\mathrm{T}$. Our application uses such a coil for an atomic magnetometry-based current controller.