N. Severijns
A5006757523- Nuclear physics research studies
- Atomic and Subatomic Physics Research
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Nuclear Physics and Applications
- Advanced NMR Techniques and Applications
- Quantum, superfluid, helium dynamics
- Atomic and Molecular Physics
- Quantum Chromodynamics and Particle Interactions
- Radiation Detection and Scintillator Technologies
- Dark Matter and Cosmic Phenomena
- Magnetic properties of thin films
- Radioactive Decay and Measurement Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Particle Detector Development and Performance
- Cold Atom Physics and Bose-Einstein Condensates
- Crystallography and Radiation Phenomena
- Magnetic Properties of Alloys
- Muon and positron interactions and applications
- Rare-earth and actinide compounds
- Theoretical and Computational Physics
- Magnetic Properties and Applications
- Nuclear reactor physics and engineering
- Particle accelerators and beam dynamics
- Advanced Chemical Physics Studies
KU Leuven
2015-2024
Université de Bordeaux
2023
Laboratoire de Physique des deux infinis Bordeaux
2023
Centre National de la Recherche Scientifique
2015-2023
Jagiellonian University
2017-2023
Institute of Physics
2017-2022
North Carolina State University
2022
Institute of Nuclear Physics, Polish Academy of Sciences
2017-2022
Johannes Gutenberg University Mainz
2022
Institut Laue-Langevin
2022
We present the result of an experiment to measure electric dipole moment (EDM) neutron at Paul Scherrer Institute using Ramsey's method separated oscillating magnetic fields with ultracold neutrons (UCN). Our measurement stands in long history EDM experiments probing physics violating time reversal invariance. The salient features this were use a Hg-199 co-magnetometer and array optically pumped cesium vapor magnetometers cancel correct for field changes. statistical analysis was performed...
We present for the first time a detailed and comprehensive analysis of experimental results that set current world sensitivity limit on magnitude electric dipole moment (EDM) neutron. have extended enhanced our earlier to include recent developments in understanding effects gravity depolarizing ultracold neutrons (UCN); an improved calculation spectrum neutrons; conservative estimates other possible systematic errors, which are also shown be consistent with more measurements undertaken...
We report on a search for ultralow-mass axionlike dark matter by analyzing the ratio of spin-precession frequencies stored ultracold neutrons and 199Hg atoms an axion-induced oscillating electric dipole moment neutron axion-wind effect. No signal consistent with is observed axion mass range 10−24≤ma≤10−17 eV. Our null result sets first laboratory constraints coupling to gluons, which improve astrophysical limits up 3 orders magnitude, also improves previous nucleons factor 40.Received 29...
The current status of precision measurements in allowed nuclear beta decay is reviewed, including neutron decay, with emphasis on their potential to look for new physics beyond the standard electroweak model. Experimental results are interpreted framework phenomenological model-independent descriptions as well some specific extensions values couplings and constraints exotic general Hamiltonian updated. ratio between axial vector obtained...
A fully analytical description of the allowed $\beta$ spectrum shape is given in view ongoing and planned measurements. Its study forms an invaluable tool search for physics beyond standard electroweak model weak magnetism recoil term. Contributions stemming from finite size corrections, mass effects, radiative corrections are reviewed. particular focus placed on atomic chemical where existing extended analytically provided. The effects QCD-induced terms discussed, cross-checks were...
The Vud element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix has traditionally been determined from analysis data in nuclear superallowed 0+ to transitions, neutron decay and pion beta decay. We show here that this can independently be mirror transitions. extracted value, |Vud| = 0.9719 +- 0.0017, is at 1.2 combined standard deviations value obtained transitions a similar precision than experiments. discuss some prospects improve its through experiments
A complete survey is presented of all half-life and branching-ratio measurements related to the isospin $T=1/2$ mirror \ensuremath{\beta} transitions ranging from $^{3}\mathrm{He}$ $^{83}\mathrm{Mo}$. No are ignored, although some rejected for cause. Using decay energies obtained in 2003 Mass Evaluation experimental $\mathit{ft}$ values then determined up $^{45}\mathrm{V}$. For first time also associated theoretical corrections needed convert these results into ``corrected'' $\mathcal{F}t$...
We study the dominant forbidden transitions in antineutrino spectra of fission actinides from 4 MeV onward using nuclear shell model. Through explicit calculation shape factor, taking into account Coulomb corrections, we show expected changes on cumulative electron and spectra. Compared to usual allowed approximation this results a minor decrease onward, whereas an increase several percent is observed that, despite their limited number, dominate spectral flux for most experimentally...
The precision of correlation measurements in neutron and nuclear $\ensuremath{\beta}$ decay has now reached the level about 1% better. At this precision, higher-order corrections such as recoil-order induced by strong interaction radiative cannot necessarily be neglected anymore. We provide here an update $\mathcal{F}t$ values isospin $T=1/2$ mirror decays including neutron, interest to determine ${V}_{\mathrm{ud}}$ quark-mixing matrix element. also overview current experimental theoretical...
Precision measurements in nuclear β decay provide sensitive means to test the structure of standard electroweak model; they also allow determination fundamental properties processes that involve lightest quarks. The primary aim such tests is find deviations from Standard Model predictions may indicate new physics. We review here status precision decay, including selected experiments neutron and discuss recent results developments. Among these developments are consideration mirror transitions...
A clock comparison experiment, analyzing the ratio of spin precession frequencies stored ultracold neutrons and 199Hg atoms, is reported. No daily variation this could be found, from which set an upper limit on Lorentz invariance violating cosmic anisotropy field b perpendicular < 2 x 10(-20) eV (95% C.L.). This first for free neutron. result also interpreted as a direct gravitational dipole moment neutron |gn| 0.3 eV/c2 m spin-dependent interaction with Sun. Analyzing Earth, based previous...
It has been proposed that there could be a mirror copy of the standard model particles, restoring parity symmetry in weak interaction on global level. Oscillations between neutral particle, such as neutron, and its counterpart potentially answer various standing issues physics today. Astrophysical studies terrestrial experiments led by ultracold neutron storage measurements have investigated to mirror-neutron oscillations imposed constraints theoretical parameters. Recently, further analysis...
We present the design of a next-generation experiment, n2EDM, currently under construction at ultracold neutron source Paul Scherrer Institute (PSI) with aim carrying out high-precision search for an electric dipole moment neutron. The project builds on experience gained previous apparatus operated PSI until 2017, and is expected to deliver order magnitude better sensitivity provision further substantial improvements. An overview experimental method setup given, requirements are derived, its...
Abstract High-precision searches for an electric dipole moment of the neutron (nEDM) require stable and uniform magnetic field environments. We present recent achievements degaussing equilibrating magnetically shielded room (MSR) n2EDM experiment at Paul Scherrer Institute. final configuration that will be used after numerous studies. The optimized procedure results in a residual has been reduced by factor two. ultra-low is achieved with full magnetic-field-coil system, large vacuum vessel...
We performed ultracold neutron storage measurements to search for additional losses due (n) mirror-neutron (n′) oscillations as a function of an applied magnetic field B. In the presence mirror B′, would be maximal B≈B′. did not observe any indication nn′ and placed lower limit on oscillation time τnn′>12.0 s at 95% C.L. B′ between 0 12.5 μT.Received 26 May 2009DOI:https://doi.org/10.1103/PhysRevD.80.032003©2009 American Physical Society
We study the dominant forbidden transitions in antineutrino spectra of fission actinides from 4 MeV onward using nuclear shell model. Through explicit calculation shape factor, we show expected changes cumulative electron and spectra. Relative to allowed approximation this results a minor decrease above MeV, whereas an increase several percent is observed that dominate spectral flux for most experimentally accessible range. Based on model calculations attempt parametrization propose...
Muonic atom spectroscopy-the measurement of the x rays emitted during formation process a muonic atom-has long standing history in probing shape and size nuclei. In fact, almost all stable elements have been subject to spectroscopy measurements absolute charge radii extracted from these typically offer highest accuracy available. However, so far only targets at least few hundred milligram could be used as it required stop muon beam directly target form atom. We developed new method relying...
A systematic on-line nuclear-orientation study of heavy isotopes by use anisotropic $\ensuremath{\alpha}$ emission is reported for the first time. The anisotropies recorded $^{199}\mathrm{At}$, $^{201}\mathrm{At}$, and $^{203}\mathrm{At}$ are remarkably pronounced strongly varying. At lower neutron number particles more preferentially emitted perpendicularly to nuclear-spin direction. This may be interpreted in terms high sensitivity $\ensuremath{\alpha}$-emission probability changes nuclear shape.
Both components of the transverse polarization electrons (sigmaT1, sigmaT2) emitted in beta-decay polarized, free neutrons have been measured. The T-odd, P-odd correlation coefficient quantifying sigmaT2, perpendicular to neutron and electron momentum, was found be R=0.008+/-0.015+/-0.005. This value is consistent with time reversal invariance significantly improves limits on relative strength imaginary scalar couplings weak interaction. obtained for associated sigmaT1,...
The final analysis of the experiment determining both components transverse polarization electrons ($\sigma_{T_{1}}$, $\sigma_{T_{2}}$) emitted in $\beta$-decay polarized, free neutrons is presented. T-odd, P-odd correlation coefficient quantifying $\sigma_{T_{2}}$, perpendicular to neutron and electron momentum, was found be $R=$ 0.004$\pm0.012\pm$0.005. This value consistent with time reversal invariance, significantly improves earlier result limits on relative strength imaginary scalar...
The neutron gyromagnetic ratio has been measured relative to that of the 199Hg atom with an uncertainty 0.8 ppm. We employed apparatus where ultracold neutrons and mercury atoms are stored in same volume report result γn/γHg=3.8424574(30).
We report a new limit on possible short range spin-dependent interaction from the precise measurement of ratio Larmor precession frequencies stored ultracold neutrons and $^{199}$Hg atoms confined in same volume. The was performed $\sim$1$\mu$ T vertical magnetic holding field with apparatus searching for permanent electric dipole moment neutron at Paul Scherrer Institute. A coupling between freely precessing polarized spins unpolarized nucleons wall material can be investigated by tiny...
Magnetic-field uniformity is of the utmost importance in experiments to measure electric dipole moment neutron. A general parametrization magnetic field terms harmonic polynomial modes proposed, going beyond linear-gradients approximation. We review main undesirable effects nonuniformities: depolarization ultracold neutrons and Larmor frequency shifts mercury atoms. The theoretical predictions for these were verified by dedicated measurements with single-chamber neutron...
The hyperfine splitting of the 5g→4f transitions in muonic 185,187Re has been measured using high resolution purity germanium detectors and compared to state-of-the-art atomic theoretical predictions. spectroscopic quadrupole moment extracted modern fitting procedures values available literature obtained from x rays natural rhenium. nuclear are 2.07(5) b 1.94(5) b, respectively for 185Re 187Re.1 MoreReceived 27 November 2019Accepted 21 February...