T. Sefzick
A5051772965- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Atomic and Molecular Physics
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- Dark Matter and Cosmic Phenomena
- Particle accelerators and beam dynamics
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced NMR Techniques and Applications
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Muon and positron interactions and applications
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Magnetic confinement fusion research
- Advanced Chemical Physics Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Scientific Research and Discoveries
- Neutrino Physics Research
- Mass Spectrometry Techniques and Applications
- Quantum and Classical Electrodynamics
- Spacecraft and Cryogenic Technologies
Forschungszentrum Jülich
2013-2022
Uppsala University
2017-2020
Institute for Theoretical and Experimental Physics
2016-2020
Kurchatov Institute
2020
Campbell Collaboration
2014
University of Delhi
2014
University of Bern
2014
University of Sheffield
2014
Heinrich Heine University Düsseldorf
2014
Johannes Gutenberg University Mainz
2014
A background-free observation of cold antihydrogen atoms is made using field ionization followed by antiproton storage, a detection method that provides the first experimental information about atomic states. More can be ionized in an hour than all antimatter have been previously reported, and production rate per incident high energy higher ever observed. The Rydberg states suggest formed via three-body recombination.
Cold antihydrogen is produced when antiprotons are repeatedly driven into collisions with cold positrons within a nested Penning trap. Efficient production takes place during many cycles of positron cooling antiprotons. A first measurement distribution states made using preionizing electric field between separated and detection regions. Surviving stripped in an ionization well that captures stores the freed antiproton for background-free detection.
Antihydrogen atoms (H¯) are confined in an Ioffe trap for 15-1000 s-long enough to ensure that they reach their ground state. Though reproducibility challenges remain making large numbers of cold antiprotons (p¯) and positrons (e(+)) interact, 5±1 simultaneously ground-state produced observed on average, substantially more than previously reported. Increases the number trapped H¯ critical if laser cooling is be demonstrated spectroscopic studies at interesting levels precision carried out.
Exclusive and kinematically complete high-statistics measurements of quasifree polarized $\stackrel{\ensuremath{\rightarrow}}{n}p$ scattering have been performed in the energy region narrow resonancelike structure ${d}^{*}$ with $I({J}^{P})=0({3}^{+})$, $M\ensuremath{\approx}2380\text{ }\text{ }\mathrm{MeV}$, $\mathrm{\ensuremath{\Gamma}}\ensuremath{\approx}70\text{ }\mathrm{MeV}$ observed recently double-pionic fusion channels...
Lasers are used for the first time to control production of antihydrogen (H ). Sequential, resonant charge exchange collisions involved in a method that is very different than only other so far-producing slow H during positron cooling antiprotons nested Penning trap. Two attractive features laser frequencies determine binding energy, and extremely cold should be possible principle-likely close what needed confinement trap, as precise spectroscopy.
Total and differential cross sections for the dp→He3η reaction have been measured near threshold He3 center-of-mass momenta in range from 17.1 MeV/c to 87.5 MeV/c. The data were taken during a slow ramping of COSY internal deuteron beam scattered on proton target detecting ejectiles with COSY-11 facility. forward–backward asymmetries deviate clearly zero above 50 indicating presence higher partial waves final state. Below fit state enhancement factor total results He3–η scattering length...
Slow antihydrogen ($\overline{\mathrm{H}}$) is produced within a Penning trap that located quadrupole Ioffe trap, the latter intended to ultimately confine extremely cold, ground-state $\overline{\mathrm{H}}$ atoms. Observed atoms in this configuration resolve debate about whether positrons and antiprotons can be brought together form divergent magnetic fields of trap. The number detected actually increases when 400 mK turned on.
For the first time a single trapped antiproton (p) is used to measure p magnetic moment μ(p). The μ(p)=μ(p)S/(ℏ/2) given in terms of its spin S and nuclear magneton (μ(N)) by μ(p)/μ(N)=-2.792 845±0.000 012. 4.4 parts per million (ppm) uncertainty 680 times smaller than previously realized. Comparing proton measured using same method trap electrodes gives μ(p)/μ(p)=-1.000 000±0.000 005 5 ppm, for μ(p)=μ(p)S/(ℏ/2), consistent with prediction CPT theorem.
Exclusive measurements of the quasifree $pn\ensuremath{\rightarrow}pp{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{\ensuremath{-}}$ reaction have been performed by means $pd$ collisions at ${T}_{p}$ $=$ 1.2 GeV using wide angle shower apparatus (WASA) detector setup cooler synchrotron COSY (Institut f\"ur Kernphysik, J\"ulich). Total and differential cross sections obtained covering energy region $\sqrt{s}$ (2.35--2.46) GeV, which includes ABC effect its associated resonance structure. No...
New data on quasifree polarized neutron-proton scattering in the region of recently observed ${d}^{*}$ resonance structure are obtained by exclusive and kinematically complete high-statistics measurements with WASA at COSY. This paper details determination beam polarization, checks character process, all ${A}_{y}$ angular distributions new partial-wave analysis, which includes producing a pole ${}^{3}{D}_{3}\ensuremath{-}{}^{3}{G}_{3}$ coupled partial waves...
Exclusive measurements of the quasi-free $np \to np\pi^0\pi^0$ reaction have been performed by means $dp$ collisions at $T_d$ = 2.27 GeV using WASA detector setup COSY. Total and differential cross sections obtained covering energy region $\sqrt s$ (2.35 - 2.46) GeV, which includes ABC effect its associated $d^*(2380)$ resonance. Adding $d^*$ resonance amplitude to that for conventional processes leads a reasonable description data. The observed in total section is agreement with predictions...
We observe a deuteron beam polarization lifetime near 1000 s in the horizontal plane of magnetic storage ring (COSY). This long spin coherence time is maintained through combination bunching, electron cooling, sextupole field corrections, and suppression collective effects current limits. record required for search an intrinsic electric dipole moment on at statistical sensitivity level approaching 10^{-29} e cm.
An exclusive measurement of the excitation function for dd->3Heppi- reaction was performed at Cooler Synchrotron COSY-Juelich with WASA-at-COSY detection system. The data were taken during a slow acceleration beam from 2.185 GeV/c to 2.400 crossing kinematic threshold eta meson production in dd->4He-eta 2.336 GeV/c. corresponding excess energy respect 4He-eta system varied -51.4MeV 22MeV. integrated luminosity experiment determined using dd->3Hen reaction. shape examined. No signal bound...
Taking advantage of both the high mass resolution COSY-11 detector and energy low-emittance proton beam cooler synchrotron COSY, we determine excitation function for pp→ppη(') reaction close to threshold. Combining these data with previous results, extract scattering length η(')-proton potential in free space be Re(a(pη(')))=0±0.43 fm Im(a(pη(')))=0.37(-0.16)(+0.40) fm.
The $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{pp}{\ensuremath{\eta}}^{\ensuremath{'}}(958)$ reaction has been measured at the cooler synchrotron COSY J\"ulich using internal beam and COSY-11 facility. total cross sections four different excess energies $Q\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.5,1.7,2.9$, $4.1\mathrm{MeV}$ have evaluated to be...
Adiabatic cooling is shown to be a simple and effective method cool many charged particles in trap very low temperatures. Up $3\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\overline{p}$ are cooled 3.5 K---${10}^{3}$ times more cold 3 lower temperature than previously reported. A second cools plasmas via the synchrotron radiation of embedded ${e}^{\ensuremath{-}}$ (with fewer $\overline{p}$) preparation for adiabatic cooling. No lost during either process---a significant advantage rare particles.
We report on a high-statistics measurement of the most basic double pionic fusion reaction $\vec{n}p \to d\pi^0\pi^0$ over energy region $d^*(2380)$ resonance by use polarized deuteron beam and observing in quasifree scattering mode. The measurements were performed with WASA detector setup at COSY. data reveal substantial analyzing powers confirm conclusions about $d^*$ obtained from unpolarized measurements. also previous under complementary kinematic conditions.
Threshold measurements of the associated strangeness production reactions pp→pK+Λ and pp→pK+Σ0 are presented. The most remarkable feature data is that at same excess energy total cross section for Σ0 appears to be about a factor 28+6−9 smaller than Λ particle. It concluded strong Σ0p final state interactions, in particular ΣN→Λp conversion reaction, likely cause depletion Σ signal. This hypothesis line with other experimental evidence literature.Received 4 November...