M. Papenbrock
A5035654721- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Black Holes and Theoretical Physics
- Advanced Data Storage Technologies
- Quantum, superfluid, helium dynamics
- Particle Detector Development and Performance
- Advanced NMR Techniques and Applications
- Medical Imaging Techniques and Applications
- Atomic and Molecular Physics
- Neutrino Physics Research
- Computational Physics and Python Applications
- Muon and positron interactions and applications
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Data Quality and Management
- Isotope Analysis in Ecology
- Scientific Computing and Data Management
- Research Data Management Practices
- Nuclear Physics and Applications
- Geophysics and Gravity Measurements
- International Science and Diplomacy
Uppsala University
2016-2021
University of Münster
2008-2020
Institute of High Energy Physics
2018-2020
Forschungszentrum Jülich
2018
Joint Institute for Nuclear Research
2018
University of Minnesota
2018
Boğaziçi University
2017
University of Turin
2017
Tbilisi State University
2016
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
2015-2016
The existence of a new force beyond the Standard Model is compelling because it could explain several striking astrophysical observations which fail standard interpretations. We searched for light vector mediator this dark force, $\mathrm{U}$ boson, with KLOE detector at DA$\Phi$NE $\mathrm{e}^{+}\mathrm{e}^{-}$ collider. Using an integrated luminosity 1.54 fb$^{-1}$, we studied process $\mathrm{e}^{+}\mathrm{e}^{-} \to \mathrm{U}\gamma$, $\mathrm{U} \mathrm{e}^{+}\mathrm{e}^{-}$, using...
The recent interest in a light gauge boson the framework of an extra U(1) symmetry motivates searches mass range below 1 GeV. We present search for such particle, dark photon, e+e−→Uγ, U→π+π− based on 28 million e+e−→π+π−γ events collected at DAΦNE by KLOE experiment. π+ π− production initial-state radiation compensates loss sensitivity previous U→e+e−, μ+μ− due to small branching ratios ρ–ω resonance region. found no evidence signal and set limit 90% CL mixing strength between photon ε2, U...
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...
Using 1.6 fb−1 of e + − → ϕ ηγ data collected with the KLOE detector at DAΦNE, Dalitz plot distribution for η π 0 decay is studied world's largest sample ∼ 4.7 · 106 events. The density parametrized as a polynomial expansion up to cubic terms in normalized dimensionless variables X and Y . experiment sensitive all charge conjugation conserving expansion, including gX 2 term. statistical uncertainty parameters improved by factor two respect earlier measurements.
A measurement of the vector to pseudoscalar conversion decay $\phi \to \pi^0 e^+e^-$ with KLOE experiment is presented. sample $\sim 9500$ signal events was selected from a data set 1.7 fb$^{-1}$ $e^+e^-$ collisions at $\sqrt{s} \sim m_{\phi}$ collected DA$\Phi$NE collider. These were used obtain first transition form factor $| F_{\phi \pi^0}(q^2) |$ and new branching ratio decay: $\rm{BR}\,(\phi e^+e^-) = (\,1.35 \pm 0.05^{\,\,+0.05}_{\,\,-0.10}\,) \times 10 ^{-5}$. The result improves...
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.
We report on measurements of the differential cross section $d\ensuremath{\sigma}/d\mathrm{\ensuremath{\Omega}}$ and first measurement analyzing power ${A}_{y}$ in $\mathrm{\ensuremath{\Delta}}(1232)$ excitation energy region reaction $pp\ensuremath{\rightarrow}{{pp}}_{s}{\ensuremath{\pi}}^{0}$ where ${{pp}}_{s}$ is a $^{1}S_{0}$ proton pair. The experiment has been performed with ANKE spectrometer at COSY-J\"ulich. data reveal peak dependence forward section, minimum zero degrees its...
We have measured the running of effective QED coupling constant $\alpha(s)$ in time-like region $0.6<\sqrt s< 0.975$ GeV with KLOE detector at DA$\Phi$NE using Initial State Radiation process $e^+e^-\to\mu^+ \mu^-\gamma$. It represents first measurement this energy region. Our results show a more than 5$\sigma$ significance hadronic contribution to $\alpha(s)$, which is strongest direct evidence both time- and space-like regions achieved single measurement. By $e^+e^-\to\pi^+\pi^-$ cross...
The pp -> ppK+K- reaction was measured below the phi threshold at a beam energy of 2.568 GeV using COSY-ANKE magnetic spectrometer. By assuming that four-body phase space is distorted only by product two-body final state interactions, fits to variety one-dimensional distributions permit evaluation differential and total cross sections. shapes in Kp Kpp invariant masses are reproduced if K-p interaction even stronger than found higher energy. cusp effect K+K- distribution K0K0bar much more...
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 $s$-...
The paper describes the commissioning of experimental equipment and machine studies required for first spin-filtering experiment with protons at a beam kinetic energy 49.3 MeV in COSY. implementation low-$\ensuremath{\beta}$ insertion made it possible to achieve lifetimes ${\ensuremath{\tau}}_{b}=8000\text{ }\text{ }\mathrm{s}$ presence dense polarized hydrogen storage-cell target areal density...
The production of the Sigma+ hyperon through pp->K+nSigma+ reaction has been investigated at four energies close to threshold, 1.826, 1.920, 1.958, and 2.020 GeV. At low energies, correlated K+pi+ pairs can only originate from so that their measurement allows total cross section for be determined. results obtained are completely consistent with values extracted study K+-proton correlation spectra in same experiment. These spectra, as well inclusive K+ momentum distributions, also provide...
The PAX Collaboration has successfully performed a spin-filtering experiment with protons at the COSY-ring. measurement allowed determination of spin-dependent polarizing cross section, that compares well theoretical prediction from nucleon–nucleon potential. test confirms can be adopted as method to polarize stored beam and present interpretation mechanism in terms proton–proton interaction is correct. outcome utmost importance view possible application antiprotons.
The unpolarised differential cross section and the two deuteron tensor analysing powers A xx yy of $$\vec dp \to \{ pp\} _s n$$ charge-exchange reaction have been measured with ANKE spectrometer at COSY storage ring. Using beams energies 1.2, 1.6, 1.8, 2.27GeV, data were obtained for small momentum transfers to a {pp} s system low excitation energy. results three lower are consistent impulse approximation predictions based upon current knowledge neutron-proton amplitudes. However, where...
The proton analysing power in $\vec{p}p$ elastic scattering has been measured at small angles COSY-ANKE 796 MeV and five other beam energies between 1.6 2.4 GeV using a polarised beam. asymmetries obtained by detecting the fast ANKE forward detector or slow recoil silicon tracking telescope are completely consistent. Although results agree well with many published data MeV, also most recent partial wave solution this energy, higher lie above predictions of angles. An updated phase shift...
In order to establish links between p-wave pion production in nucleon-nucleon collisions and low energy three-nucleon scattering, an extensive programme of experiments on is currently underway at COSY-ANKE. The final proton pair detected very excitation energy, leading S-wave diproton, denoted here as {pp}_s. We now report measurements the differential cross section analysing power pol{p}p->{pp}_s pi^0$ reaction 353 MeV. Both observables can be described terms s- d-wave and, by using phase...
A value for the mass of eta meson has been determined at COSY-ANKE facility through measurement a set deuteron laboratory beam momenta and associated 3He center-of-mass in d+p -> 3He+X reaction. The was then identified by missing-mass peak production threshold determined. individual were fixed with relative precision 3 x 10^-5 values around GeV/c using polarized inducing an artificial depolarizing spin resonance, which occurs well-defined frequency. final-state two-body 3He+eta reaction...
In order to measure the mass of $\ensuremath{\eta}$ meson with high accuracy using $dp\ensuremath{\rightarrow}^{3}\mathrm{He}\ensuremath{\eta}$ reaction, momentum circulating deuteron beam in Cooler Synchrotron COSY Forschungszentrum J\"ulich has be determined unprecedented precision. This been achieved by studying spin dynamics polarized beam. By depolarizing through use an artificially induced resonance, it was possible evaluate its $p$ a precision...