A. Täschner
A5055014816- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Quantum, superfluid, helium dynamics
- Advanced NMR Techniques and Applications
- Particle Detector Development and Performance
- Atomic and Molecular Physics
- Radiation Detection and Scintillator Technologies
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Dark Matter and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Advanced Chemical Physics Studies
- Superconducting Materials and Applications
- Advanced Optical Sensing Technologies
- Cold Atom Physics and Bose-Einstein Condensates
- Distributed and Parallel Computing Systems
- Microwave Imaging and Scattering Analysis
- Photonic Crystal and Fiber Optics
- Advanced Frequency and Time Standards
- Rocket and propulsion systems research
- Ion-surface interactions and analysis
- Gamma-ray bursts and supernovae
GSI Helmholtz Centre for Heavy Ion Research
2016-2021
University of Münster
2009-2020
Forschungszentrum Jülich
2004-2015
University of Sheffield
2014
University of Delhi
2014
University of Bern
2014
Heinrich Heine University Düsseldorf
2014
Johannes Gutenberg University Mainz
2014
Campbell Collaboration
2014
Max Planck Institute for Nuclear Physics
2007
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...
The differential and total cross sections for the dp→3Heη reaction have been measured in a high precision statistics COSY-ANKE experiment near threshold using continuous beam energy ramp up to an excess Q of 11.3 MeV with essentially 100% acceptance. kinematics allowed mean value be determined about 9 keV. Evidence is found effects higher partial waves Q≳4 MeV. very rapid rise section its maximum within 0.5 implies large η3He scattering length hence presence quasibound state extremely close...
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...
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...
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.
A high statistics measurement of the pp --> ppeta reaction at an excess energy Q = 15.5 MeV has been performed internal beam facility COSY-11. The stochastically cooled proton and used detection system allowed to determine momenta outgoing protons with a precision 4 MeV/c (sigma) in center-of-mass frame. determination four-momentum vectors both derive complete kinematical information ppeta-system. An unexpectedly large enhancement occupation density regions low proton-eta relative is...
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.
The deuteron tensor analysing power T20 of the d→p→He3η reaction has been measured at COSY-ANKE facility in small steps excess energy Q up to Q=11 MeV. Despite square production amplitude varying by over a factor five through this range, shows little dependence. This is evidence that final state interaction causing variation not influenced spin configuration entrance channel. weak angular dependence observed for provides useful insight into structure near threshold.
Exclusive and kinematically complete measurements of the double pionic fusion to ${}^{3}\mathrm{He}$ have been performed in energy region so-called ABC effect, which denotes a pronounced low-mass enhancement $\ensuremath{\pi}\ensuremath{\pi}$-invariant mass spectrum. The experiments were carried out with WASA detector setup at COSY (the cooler synchrotron Forschungszentrum J\"ulich). Similar observations basic $pn\ensuremath{\rightarrow}d{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ reaction...
The total cross section of the reaction pp→ppK+K− has been measured at excess energies Q=10MeV and 28 MeV with magnetic spectrometer COSY-11. new data show a significant enhancement compared to pure phase space expectations or calculations within one boson exchange model. In addition, we present invariant mass spectra two particle subsystems. While K+K− system is rather constant for different masses, there an in pK− towards lower masses which could least be partially connected influence...
Measurements of η meson production in proton-deuteron collisions have been performed using the COSY-11 facility at COSY (Jülich). Results on total and differential cross sections for pd→He3η reaction are presented five excess energies between Q=5.0 Q=40.6 MeV. The angular distributions show a transition from an almost isotropic emission close to threshold highly anisotropic distribution higher energies. reveal strong η−He3 final state interaction, corresponding scattering length...
The differential and total cross sections for the $\mathit{dp}\ensuremath{\rightarrow}^{3}\mathrm{He}\ensuremath{\eta}$ reaction have been measured at COSY--ANKE excess energies of 19.5, 39.4, 59.4 MeV over full angular range. results are in line with trends apparent from detailed near-threshold studies also largely agree those CELSIUS, though present data much better coverage near forward backward directions, thus allowing firmer conclusions to be drawn. While 19.5 can described terms $s$-...
Taking advantage of both the low-emittance proton-beam Cooler Synchrotron COSY and high momentum precision COSY-11 detector system, mass distribution eta' meson was measured with a resolution 0.33 MeV/c^2 (FWHM), improving experimental by almost an order magnitude respect to previous results. Based on sample more than 2300 reconstructed pp --> events total width determined be 0.226 +- 0.017(stat.) 0.014(syst.) MeV/c^2.
Dalitz plot distribution of the $\eta\to\pi^+\pi^-\pi^0$ decay is determined using a data sample $1.2\cdot 10^7$ $\eta$ mesons from $pd\to ^3\textrm{He}\eta$ reaction at 1 GeV collected by WASA detector COSY.
Measurements of the analyzing power for pp-->pp eta reaction have been performed at excess energies Q=10 and 36 MeV. The determined is essentially consistent with zero, implying dominance s wave both energies. angular dependence power, combined isospin total cross section meson production in nucleon-nucleon collisions, reveal that excitation nucleon to S11(1535) resonance predominantly due exchange pi between colliding nucleons.
The reaction pp->pppi0pi0 has been investigated at a beam energy of 1.4 GeV using the WASA-at-COSY facility. total cross section is found to be (324 +- 21_systematic 58_normalization) mub. In order study production mechanism, differential kinematical distributions have evaluated. indicate that both initial state protons are excited into intermediate Delta(1232) resonances, each decaying proton and single pion, thereby producing pion pair in final state. No significant contribution Roper...
Total cross sections for the quasifree $\mathit{pn}\ensuremath{\rightarrow}\mathit{pn}\ensuremath{\eta}$ reaction in range from kinematical threshold up to 20 MeV excess energy have been determined. At they exceed corresponding $\mathit{pp}\ensuremath{\rightarrow}\mathit{pp}\ensuremath{\eta}$ by a factor of about 3 contrast 6 established higher energies. To large extent, observed decrease ratio...
The WASA-at-COSY experiment has collected $3\ifmmode\times\else\texttimes\fi{}{10}^{7}$ events with $\ensuremath{\eta}$ mesons produced via the reaction $pd\ensuremath{\rightarrow}^{3}\mathrm{He}\phantom{\rule{0.16em}{0ex}}\ensuremath{\eta}$ at $\mathrm{T}=1.0\phantom{\rule{4pt}{0ex}}\mathrm{GeV}$. Using this data set, we evaluate branching ratios of decays $\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}$,...