R. Joosten
A5063591531- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- Quantum, superfluid, helium dynamics
- Advanced NMR Techniques and Applications
- Dark Matter and Cosmic Phenomena
- Radiation Effects in Electronics
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Plasma Diagnostics and Applications
- Radiation Therapy and Dosimetry
- Magnetic confinement fusion research
- Boron Compounds in Chemistry
- Nuclear reactor physics and engineering
- Nuclear Issues and Defense
- Mass Spectrometry Techniques and Applications
- Random Matrices and Applications
- Astrophysics and Cosmic Phenomena
University of Bonn
2009-2024
Schiller International University
2024
A. Alikhanyan National Laboratory
2023
University of Aveiro
2020-2023
European Organization for Nuclear Research
2018-2020
University of Tübingen
2011
Lawrence Berkeley National Laboratory
1998-2000
University of California, Berkeley
1998
Max Planck Institute for Nuclear Physics
1995
We report the first search for dark sectors performed at NA64 experiment employing a high energy muon beam and missing energy-momentum technique. Muons from M2 beamline CERN Super Proton Synchrotron with momentum of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>160</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>GeV</a:mi><a:mo>/</a:mo><a:mi>c</a:mi></a:mrow></a:math> are directed to an active target. The signal signature consists single scattered...
Total and differential cross sections for the reaction p(gamma,eta)p have been measured photon energies in range from 750 MeV to 3 GeV. The low-energy data are dominated by S11 wave which has two poles energy region below 2 Eleven nucleon resonances observed their decay into peta. At medium we find evidence a new resonance N(2070)D15 with (M,Gamma)=(2068+/-22, 295+/-40) MeV. gamma above 1.5 GeV, strong peak forward direction develops, signaling exchange of vector mesons t channel.
Single π0 photoproduction has been studied with the CB-ELSA experiment at Bonn using tagged photon energies between 0.3 and 3.0 GeV. The experimental setup covers a very large solid angle of ∼98% 4π. Differential cross sections dσ/dΩ have measured. Complicated structures in angular distributions indicate variety different resonances being produced s channel intermediate state γp→N∗(Δ∗)→pπ0. A combined analysis including data presented this letter along other sets reveals contributions from...
We report on the first measurement of exclusive single-photon muoproduction proton by COMPASS using 160 GeV/c polarised μ+ and μ− beams CERN SPS impinging a liquid hydrogen target. determine dependence average measured cross sections for deeply virtual Compton scattering squared four-momentum transfer t from initial to final proton. The slope B t-dependence is fitted with single exponential function, which yields B=(4.3±0.6stat|sys−0.3+0.1)(GeV/c)−2. This result can be converted into...
We study the spin-exotic $J^{PC} = 1^{-+}$ amplitude in single-diffractive dissociation of 190 GeV$/c$ pions into $\pi^-\pi^-\pi^+$ using a hydrogen target and confirm $\pi_1(1600) \to \rho(770) \pi$ amplitude, which interferes with nonresonant $1^{-+}$ amplitude. demonstrate that conflicting conclusions from previous studies on these amplitudes can be attributed to different analysis models treatment dependence squared four-momentum transfer we thus reconcile their experimental findings....
Two-kaon production in proton-deuteron collisions has been studied at three energies close to threshold using a calibrated magnetic spectrograph measure the final $^{3}\mathrm{He}$ and vertex detector ${K}^{+}{K}^{\ensuremath{-}}$ pair. Differential total cross sections are presented for of \ensuremath{\phi}-mesons, decaying through $\ensuremath{\phi}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$, as well prompt production. The seems follow phase space both its differential...
We report on a measurement of hard exclusive $\pi^0$ muoproduction the proton by COMPASS using 160 GeV/$c$ polarised $\mu^+$ and $\mu^-$ beams CERN SPS impinging liquid hydrogen target. From average measured cross sections, virtual-photon section is determined as function squared four-momentum transfer between initial final in range $0.08\,(\text{GeV/}c)^2 < |t| 0.64\,(\text{GeV/}c)^2$. The kinematics are $\langle Q^2 \rangle =2.0\; {(\text{GeV}/c)^2}$, \nu = 12.8\; {\text{GeV}}$, x_{Bj}...
A search for dark sectors is performed using the unique M2 beam line at CERN Super Proton Synchrotron. New particles (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>X</a:mi></a:math>) could be produced in bremsstrahlung-like reaction of high-energy 160 GeV positively charged muons impinging on an active target, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>μ</c:mi><c:mi>N</c:mi><c:mo...
The production of vector mesons in deep inelastic scattering is an interesting yet scarsely explored channel to study the transverse spin structure nucleon and related phenomena. COMPASS collaboration has performed first measurement Collins Sivers asymmetries for inclusively produced $\rho^0$ mesons. analysis based on data set collected $2010$ using a $160\,\,\rm{GeV}/c$ $\mu^+$ beam impinging transversely polarized $\rm{NH}_3$ target. $\rho^{0}$ are selected from oppositely charged hadron...
Using a novel analysis technique, the gluon polarisation in nucleon is re-evaluated using longitudinal double-spin asymmetry measured cross section of semi-inclusive single-hadron muoproduction with photon virtuality $$Q^2>1~(\mathrm{GeV}/c)^2$$ . The data were obtained by COMPASS experiment at CERN 160 GeV/c polarised muon beam impinging on $$^6$$ LiD target. By analysing full range hadron transverse momentum $$p_\mathrm{T}$$ , different -dependences underlying processes are separated...
Backward \ensuremath{\omega}(782)-meson production in the pd${\ensuremath{\rightarrow}}^{3}$He\ensuremath{\omega} reaction has been measured from threshold up to an \ensuremath{\omega} center-of-mass momentum of 625 MeV/c. The averaged squared amplitude rises rapidly a maximum value about 70 nb/sr at 180 MeV/c, decreasing thereafter. This striking behavior, which is very similar that already observed for...
The K− over K+ multiplicity ratio is measured in deep-inelastic scattering, for the first time kaons carrying a large fraction z of virtual-photon energy. data were obtained by COMPASS collaboration using 160 GeV muon beam and an isoscalar 6LiD target. regime scattering ensured requiring Q2>1(GeV/c)2 photon virtuality W>5GeV/c2 invariant mass produced hadronic system. Kaons are identified momentum range from 12 GeV/c to 40 GeV/c, thereby restricting Bjorken-x 0.01<x<0.40. z-dependence...
A set of measurements azimuthal asymmetries in the production pairs identified hadrons deep-inelastic scattering muons on transversely polarised 6LiD (deuteron) and NH3 (proton) targets is presented. All available data collected years 2003–2004 2007/2010 with COMPASS spectrometer using a muon beam 160GeV/c at CERN SPS were analysed. The provide access to transversity distribution functions via fragmentation function that principle may be independently obtained from e+e− annihilation data....
New results are presented on a high-statistics measurement of Collins and Sivers asymmetries charged hadrons produced in deep inelastic scattering muons transversely polarized ^{6}LiD target. The data were taken 2022 with the COMPASS spectrometer using 160 GeV muon beam at CERN, statistically balancing existing proton targets. first from about two-thirds new have total uncertainties smaller by up to factor three compared previous deuteron measurements. Using all results, both transversity...
Meson photoproduction is a key tool for the experimental investigation of nucleon excitation spectrum. To disentangle specific couplings resonances, in addition to rather well measured pion and eta channels it mandatory obtain information on involving strange vector mesons higher mass pseudoscalar mesons, associated multi-particle final states with both charged neutral particles. In this respect, new BGO-OD experiment at ELSA accelerator University Bonn's Physikalisches Institut provides...
The cross section for the pd3Heπ+π− reaction has been measured in a kinematically complete experiment at c.m. excess energy of Q=70 MeV. striking and angular distributions are reproduced simple model calculation where it is assumed that dominated by p-wave π+π− pairs. This contrast to results inclusive measurements somewhat higher beam energies which show strong s-wave ABC enhancement low ππ masses.Received 24 December 1998DOI:https://doi.org/10.1103/PhysRevC.60.061002©1999 American Physical Society
The reaction pp -> K^+ + (Lambda p) has been measured at T_p = 1.953 GeV and \Theta 0 deg with a high missing mass resolution in order to study the Lambda p final state interaction. Narrow S -1 resonances predicted by bag model calculations are not visible spectrum. Small structures observed previous experiment confirmed. Upper limits for production cross section of narrow resonance deduced masses between 2058 2105 MeV/c^2.
A light-element radioactive ion-beam capability has been developed at the LBNL 88-Inch Cyclotron. The system is based on coupled-cyclotrons method and utilizes short-lived species, e.g., 11C, 14O, 13N produced by (p,n) (p,alpha) reactions Biomedical Isotope Facility In a first experiment, 197Au(11C,xn)208-xAt excitation functions have measured for energies ranging from Coulomb barrier up to 110 MeV using beam of 11C with intensities (1-2)x10(8) ions/sec target. results this experiment are...
Abstract We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive $$\rho ^0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>ρ</mml:mi> <mml:mn>0</mml:mn> </mml:msup> </mml:math> meson muoproduction at COMPASS using 160 GeV/ c polarised $$ \mu ^{+}$$ <mml:mi>μ</mml:mi> <mml:mo>+</mml:mo> and ^{-}$$ <mml:mo>-</mml:mo> beams impinging liquid hydrogen target. The covers the kinematic range 5.0 $$c^2$$ <mml:mi>c</mml:mi>...
Hadron leptoproduction in Semi-Inclusive measurements of Deep-Inelastic Scattering (SIDIS) on unpolarised nucleons allows one to get information the intrinsic transverse momentum quarks a nucleon and Boer-Mulders function through measurement azimuthal modulations cross section. These were recently measured by HERMES experiment at DESY proton deuteron targets, COMPASS using CERN SPS muon beam $^6$LiD target. In both cases, amplitudes $\cosϕ_h$ $\cos 2ϕ_h$ show strong kinematic dependences for...