E. Widmann
A5002908349- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Atomic and Molecular Physics
- Atomic and Subatomic Physics Research
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum, superfluid, helium dynamics
- Dark Matter and Cosmic Phenomena
- Nuclear physics research studies
- Muon and positron interactions and applications
- Particle Detector Development and Performance
- Advanced Chemical Physics Studies
- Particle accelerators and beam dynamics
- Radioactive Decay and Measurement Techniques
- Radiation Detection and Scintillator Technologies
- Nuclear Physics and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Particle Accelerators and Free-Electron Lasers
- High-pressure geophysics and materials
- Quantum Mechanics and Applications
- Superconducting Materials and Applications
- Advanced Frequency and Time Standards
- Advanced NMR Techniques and Applications
- Ionosphere and magnetosphere dynamics
- Electron and X-Ray Spectroscopy Techniques
Stefan Meyer Institute for Subatomic Physics
2015-2024
ETH Zurich
2022-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Milano
2022-2024
University of Milan
2022-2024
Austrian Academy of Sciences
2014-2023
P.N. Lebedev Physical Institute of the Russian Academy of Sciences
2022
University of Turku
2022
Tokyo Institute of Technology
2010-2022
A. Alikhanyan National Laboratory
2019-2020
Istituto Nazionale di Fisica Nucleare, Sezione di Torino
2019-2020
The $\bar{K}N$ system at threshold is a sensitive testing ground for low energy QCD, especially the explicit chiral symmetry breaking. Therefore, we have measured $K$-series x rays of kaonic hydrogen atoms DA$\Phi$NE electron-positron collider Laboratori Nazionali di Frascati, and determined most precise values strong-interaction energy-level shift width $1s$ atomic state. As x-ray detectors, used large-area silicon drift detectors having excellent timing resolution, which were developed...
Delayed annihilation of antiprotons stopped in liquid helium has been observed, revealing that about 3.6% are trapped long-lived metastable states. No delayed component was found either nitrogen or argon. The observed time distribution shows fast-decaying components followed by a major part with decay constant 3 \ensuremath{\mu}sec.
Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart—hydrogen—is one of most precisely investigated and best understood systems in physics research. High-resolution comparisons both provide sensitive tests CPT symmetry, which fundamental symmetry Standard Model elementary particle physics. Any measured difference would point violation thus new Here we report development antihydrogen source using cusp trap for in-flight spectroscopy. A total 80 atoms are...
A bstract We present results of the Relic Axion Dark-Matter Exploratory Setup (RADES), a detector which is part CERN Solar Telescope (CAST), searching for axion dark matter in 34.67 μ eV mass range. radio frequency cavity consisting 5 sub-cavities coupled by inductive irises took physics data inside CAST dipole magnet first time using this filter-like haloscope geometry. An exclusion limit with 95% credibility level on axion-photon coupling constant g aγ ≳ 4 × 10 − 13 GeV 1 over range 34 ....
A femtosecond optical frequency comb and continuous-wave pulse-amplified laser were used to measure 12 transition frequencies of antiprotonic helium fractional precisions $(9--16)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$. One these is between two states having microsecond-scale lifetimes hitherto unaccessible our precision spectroscopy method. Comparisons with three-body QED calculations yielded an antiproton-to-electron mass ratio ${M}_{\overline{p}}/{m}_{e}=1836.152\text{ }674(5)$.
We have observed the first laser-induced resonant transitions in antiprotonic helium atoms. These occur between metastable states and Auger dominated short lived states, show that anomalous longevity of antiprotons previously media results from formation high-n high-l atomic p\ifmmode\bar\else\textasciimacron\fi{}${\mathrm{He}}^{+}$. The transition with vacuum wavelength 597.259\ifmmode\pm\else\textpm\fi{}0.002 nm is tentatively assigned to (n,l)=(39,35)\ensuremath{\rightarrow}(38,34).
The x-ray cascade from antiprotonic atoms was studied for $^{208}\mathrm{Pb}$ and $^{209}\mathrm{Bi}$. Widths shifts of the levels due to strong interaction were determined. Using modern antiproton-nucleus optical potentials, neutron densities in nuclear periphery deduced. Assuming two-parameter Fermi distributions (2pF) describing proton densities, rms radii deduced both nuclei. difference $\ensuremath{\Delta}{r}_{\mathit{np}}$ equal...
We have measured the proton energy distribution from 4He(stopped K−,p) reaction by means of time-of-flight. A mono-energetic peak was observed, which is interpreted as formation a new kind neutral tribaryon S0(3115) with isospin T=1 and strangeness S=−1. The mass width state were deduced to be 3117.0−4.4+1.5MeV/c2 <21MeV/c2, respectively. mainly decays into ΣNN.
We review recent progress in the laser and microwave spectroscopy of antiprotonic helium atoms carried out at CERN's Antiproton Decelerator facility (AD). Laser transitions were here induced between Rydberg states (n, ℓ) (n ± 1, ℓ − 1) ∼ 40 ≲ n 1 being principal orbital angular momentum quantum numbers antiproton orbit). Successive refinements experimental techniques improved fractional precision on frequencies from 3 parts 106 to ∼1 part 108. These included a radiofrequency quadrupole...
Abstract The precise measurement of forces is one way to obtain deep insight into the fundamental interactions present in nature. In context neutral antimatter, gravitational interaction high interest, potentially revealing new that violate weak equivalence principle. Here we report on a successful extension tool from atom optics—the moiré deflectometer—for acceleration slow antiprotons. setup consists two identical transmission gratings and spatially resolving emulsion detector for...
We demonstrate the laser excitation of $n=3$ state positronium (Ps) in vacuum. A combination a specially designed pulsed slow positron beam and high-efficiency converter target was used to produce Ps. Its annihilation recorded by single-shot lifetime spectroscopy. Pulsed level at wavelength $\ensuremath{\lambda}\ensuremath{\approx}205$ nm monitored via Ps photoionization induced second intense pulse $\ensuremath{\lambda}=1064$ nm. About 15% overall emitted into vacuum excited photoionized....
We observed a distinct peak in the Λp invariant mass spectrum of He3(K−,Λp)n, well below mK+2mp, i.e., threshold K− to be bound two protons. By selecting relatively large momentum-transfer region q=350∼650 MeV/c, one can kinematically separate from quasi-free process, K‾N→K‾N followed by non-resonant absorption spectator-nucleons K‾NN→ΛN. found that simplest fit gives us Breit–Wigner pole position at BKpp=47±3(stat.)−6+3(sys.) MeV having width ΓKpp=115±7(stat.)−20+10(sys.) MeV, and S-wave...
Six laser-resonant transitions have been detected in metastable antiprotonic helium atoms produced at the CERN Antiproton Decelerator. They include UV from last states $v\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}n\ensuremath{-}\ensuremath{\ell}\ensuremath{-}1\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ and 1 cascades. Zero-density frequencies were obtained measured pressure shifts with fractional precisions between...
A radio frequency quadrupole decelerator and achromatic momentum analyzer were used to decelerate antiprotons produce $\overline{p}^{4}\mathrm{H}\mathrm{e}^{+}$ $\overline{p}^{3}\mathrm{H}\mathrm{e}^{+}$ atoms in ultra-low-density targets, where collision-induced shifts of the atomic transition frequencies negligible. The at near-vacuo conditions measured by laser spectroscopy fractional precisions $(6--19)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$. By comparing these with QED...
We have measured the Balmer-series x-rays of kaonic $^4$He atoms using novel large-area silicon drift x-ray detectors in order to study low-energy $\bar{K}$-nucleus strong interaction. The energy $3d \to 2p$ transition was determined be 6467 $\pm$ 3 (stat) 2 (syst) eV. resulting strong-interaction energy-level shift is agreement with theoretical calculations, thus eliminating a long-standing discrepancy between theory and experiment.
A model where a Dirac fermion is coupled to background dilaton field considered study s-wave scattering of by back ground black hole. It found that an uncomfortable situation towards information loss scenario arises when one loop correction gets involved during bosonization.
Excitation spectra of $^{11}\mathrm{C}$ are measured in the $^{12}\mathrm{C}(p,d)$ reaction near ${\ensuremath{\eta}}^{\ensuremath{'}}$ emission threshold. A proton beam extracted from synchrotron SIS-18 at GSI with an incident energy 2.5 GeV impinges on a carbon target. The momenta deuterons emitted 0\ifmmode^\circ\else\textdegree\fi{} precisely fragment separator (FRS) operated as spectrometer. In contrast to theoretical predictions possible existence deeply bound...
The possible existence of deeply bound $\bar K$-nucleus states (kaonic nuclei) has been widely discussed as a consequence the strongly attractive K N$ interaction in I = 0 channels. For simplest kaonic nucleus, KNN$, we observed significant peak structure that can be interpreted ``$K^-pp$'' state using $^3$He$(K^-,N)$ reactions at J-PARC. To further understand nuclei, have proposed and prepared an experiment to precisely measure NNN$ system $^4$He$(K^-,N)$ first step towards comprehensive...