Yu. Valdau
A5026591891- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- Nuclear physics research studies
- Atomic and Subatomic Physics Research
- High-Energy Particle Collisions Research
- Advanced NMR Techniques and Applications
- Particle Accelerators and Free-Electron Lasers
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Magnetic confinement fusion research
- Dark Matter and Cosmic Phenomena
- Particle accelerators and beam dynamics
- Radiation Detection and Scintillator Technologies
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Chemical Physics Studies
- Magnetic properties of thin films
- Advanced Data Storage Technologies
- Scientific Computing and Data Management
- Advanced Electron Microscopy Techniques and Applications
- Physics of Superconductivity and Magnetism
- Geophysical and Geoelectrical Methods
- Distributed and Parallel Computing Systems
- Research Data Management Practices
- Muon and positron interactions and applications
Forschungszentrum Jülich
2013-2024
Petersburg Nuclear Physics Institute
2009-2020
University of Bonn
2012-2016
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...
The pp→pK+Y0 reaction has been studied for hyperon masses m(Y0)⩽1540MeV/c2 at COSY-Jülich by using a 3.65 GeV/c circulating proton beam incident on an internal hydrogen target. Final states comprising two protons, one positively charged kaon and negatively pion have identified with the ANKE spectrometer. Such configurations are sensitive to production of ground state Λ Σ0 hyperons as well Σ0(1385) Λ(1405) resonances. Applying invariant- missing-mass techniques, overlapping excited could be...
A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, tune-defined as number of precessions per turn-is given by ν(s)=γG (γ Lorentz factor, G gyromagnetic anomaly). At 970 MeV/c, deuteron spins coherently precess at a frequency ≈120 kHz in Cooler Synchrotron COSY. The deduced from up-down asymmetry deuteron-carbon scattering. time interval 2.6 s, was determined with precision order 10^{-8}, 1×10^{-10} for continuous 100 s accelerator cycle. This...
The production of phi mesons in the collisions 2.83 GeV protons with C, Cu, Ag, and Au at forward angles has been measured via -> K+K- decay using COSY-ANKE magnetic spectrometer. meson cross section follows a target mass dependence A^0.56+/-0.02 momentum region 0.6-1.6 GeV/c. comparison data model calculations suggests that in-medium width is about an order magnitude larger than its free value.
Based on the notion that local dark-matter field of axions or axionlike particles (ALPs) in our Galaxy induces oscillating couplings to spins nucleons and nuclei (via electric dipole moment latter and/or paramagnetic axion-wind effect), we establish feasibility a new method search for ALPs storage rings. previous work allows us maintain in-plane polarization stored deuteron beam few hundred seconds, perform first proof-of-principle experiment at Cooler Synchrotron (COSY) scan momenta near...
This paper presents the successful application of a phase-lock feedback system to maintain resonance condition radio frequency (rf) spin rotator (specifically, an rf Wien filter) with respect 120 kHz precession in Cooler Synchrotron (COSY) storage ring. Real-time monitoring and filter signal allows relative phase between two be stabilized at arbitrary setpoint. The compensates for deviations by adjusting and/or as needed. With this method, variation demand standard deviation...
This paper describes a time-marking system that enables measurement of the in-plane (horizontal) polarization 0.97-GeV/c deuteron beam circulating in Cooler Synchrotron (COSY) at Forschungszentrum J\"ulich. The clock time each polarimeter event is used to unfold 120-kHz spin precession and assign events bins according direction horizontal polarization. After accumulation for one or more seconds, down-up scattering asymmetry can be calculated matched sinusoidal function whose magnitude...
The production of $\ensuremath{\varphi}$ mesons in proton collisions with C, Cu, Ag, and Au targets has been studied via the $\ensuremath{\varphi}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$ decay at an incident beam energy 2.83 GeV using ANKE detector system COSY. For first time, momentum dependence nuclear transparency ratio, in-medium width, differential cross section for $\ensuremath{\varphi}$-meson forward angles have determined these over range 0.6--1.6 GeV/$c$. There are...
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...
The proposed method exploits charged particles confined as a storage ring beam (proton, deuteron, possibly $^3$He) to search for an intrinsic electric dipole moment (EDM) aligned along the particle spin axis. Statistical sensitivities could approach 10$^{-29}$ e$\cdot$cm. challenge will be reduce systematic errors similar levels. adjusted preserve polarisation, initially parallel velocity, times in excess of 15 minutes. Large radial fields, acting through EDM, rotate polarisation from...
The quasifree $pn\ensuremath{\rightarrow}d\ensuremath{\phi}$ reaction has been studied at the Cooler Synchrotron COSY---J\"ulich, using internal proton beam incident on a deuterium cluster-jet target and detecting fast deuteron in coincidence with ${K}^{+}{K}^{\ensuremath{-}}$ decay of $\ensuremath{\phi}$ meson. energy dependence total differential cross sections are extracted for excess energies up to 80 MeV by determining Fermi momentum neutron an event-by-event basis. Though these...
Differential and total cross sections for the pp -> ppK+K- reaction have been measured at a proton beam energy of 2.83 GeV using COSY-ANKE magnetic spectrometer. Detailed model descriptions fitted to variety one-dimensional distributions permit separation phi section from that non-phi production. The differential spectra show higher partial waves represent majority an excess 76 MeV, whose dependence would then seem require some s-wave phi-p enhancement near threshold. data can be described...
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...
Measurements of the $\mathit{pd}\ensuremath{\rightarrow}{p}_{\text{sp}}{\mathit{dK}}^{+}{K}^{\ensuremath{-}}$ reaction, where ${p}_{\text{sp}}$ is a spectator proton, have been undertaken at Cooler Synchrotron COSY-J\"ulich by detecting fast deuteron in coincidence with ${K}^{+}{K}^{\ensuremath{-}}$ pair ANKE facility. Although proton beam energy was fixed, moving target neutron allowed values nonresonant quasifree $\mathit{pn}\ensuremath{\rightarrow}{\mathit{dK}}^{+}{K}^{\ensuremath{-}}$...
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 cross section for inclusive multipion production in the $pp\ensuremath{\rightarrow}ppX$ reaction was measured at COSY-ANKE four beam energies, 0.8, 1.1, 1.4, and 2.0 GeV, low excitation energy final $pp$ system, such that diproton quasiparticle is $^{1}S_{0}$ state. At three higher missing-mass ${M}_{X}$ spectra show a strong enhancement ${M}_{X}$, corresponding to an Abashian-Booth-Crowe effect moves steadily larger values as increased. Despite structure looking very different 0.8...