J.H. Koivuniemi
A5102873260- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Advanced NMR Techniques and Applications
- Superconducting Materials and Applications
- Particle Detector Development and Performance
- Physics of Superconductivity and Magnetism
- Particle Accelerators and Free-Electron Lasers
- Cold Atom Physics and Bose-Einstein Condensates
- Dark Matter and Cosmic Phenomena
- Particle accelerators and beam dynamics
- NMR spectroscopy and applications
- Spacecraft and Cryogenic Technologies
- Advanced MRI Techniques and Applications
- Geophysics and Gravity Measurements
- Astronomy and Astrophysical Research
- Muon and positron interactions and applications
- Radiation Detection and Scintillator Technologies
- Superconducting and THz Device Technology
- Magnetic Field Sensors Techniques
- Radio Frequency Integrated Circuit Design
- DNA and Biological Computing
- Bayesian Methods and Mixture Models
University of Illinois Urbana-Champaign
2016-2024
University of Aveiro
2019-2023
A. Alikhanyan National Laboratory
2023
Ruhr University Bochum
2013-2023
University of Miyazaki
2020-2023
LIP - Laboratory of Instrumentation and Experimental Particle Physics
2020-2023
Charles University
2016-2023
Yamagata University Hospital
2016-2023
Chubu University
2020-2023
University of Illinois System
2020-2023
First measurements of the Collins and Sivers asymmetries charged hadrons produced in deep-inelastic scattering muons on a transversely polarized 6-LiD target are presented. The data were taken 2002 with COMPASS spectrometer using muon beam CERN SPS at 160 GeV/c. asymmetry turns out to be compatible zero, as does measured within present statistical errors.
The COMPASS Collaboration at CERN has measured the transverse spin azimuthal asymmetry of charged hadrons produced in semi-inclusive deep inelastic scattering using a 160 GeV μ+ beam and transversely polarised NH3 target. Sivers proton been extracted Bjorken x range 0.003<x<0.7. new measurements have small statistical systematic uncertainties few percent confirm with considerably better accuracy previous measurement. is found to be compatible zero for negative positive hadrons, clear...
The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use CERN SPS 190 GeV/c π^{-} beam and a transversely polarized ammonia target. Three giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/c^{2} 8.5 GeV/c^{2}. Within experimental uncertainties, observed sign Sivers asymmetry found be consistent...
New results for the double spin asymmetry A1p and proton longitudinal structure function g1p are presented. They were obtained by COMPASS Collaboration using polarised 200 GeV muons scattered off a longitudinally NH3 target. The data collected in 2011 complement those recorded 2007 at 160 GeV, particular lower values of x. improve statistical precision g1p(x) about factor two region x≲0.02. A next-to-leading order QCD fit to g1 world is performed. It leads new determination quark...
Measurements of the Collins and Sivers asymmetries for charged pions neutral kaons produced in semi-inclusive deep-inelastic scattering high energy muons off transversely polarised protons are presented. The results were obtained using all available COMPASS proton data, which taken years 2007 2010. exhibit valence region a non-zero signal there hints also kaons. found to be positive compatible with zero otherwise.
A new state of rotating superfluid $^{3}\mathit{A}$ has been found. Instead quantized vortex lines, it consists a continuous sheet. The sheet as backbone topologically stable domain wall called soliton, to which the vorticity is bound. folds equidistant layers that fill uniformly container. can easily be created experimentally in spite its higher energy. Its identification deduced from nuclear magnetic resonance.
Four alternative but topologically different structures of vorticity exist in rotating ${}^{3}\mathrm{H}\mathrm{e}\ensuremath{-}A$. As a function magnetic field ( $H$) and rotation velocity $(\ensuremath{\Omega})$, we identify with NMR the type vortex which is nucleated during cooling from normal to superfluid phase. The measurements are compared calculated equilibrium phase diagram vortices $H\ensuremath{-}\ensuremath{\Omega}$ plane at temperatures $T\ensuremath{\lesssim}{T}_{c}$. Slow...
First measurements of azimuthal asymmetries in hadron-pair production deep-inelastic scattering muons on transversely polarised ^6LiD (deuteron) and NH_3 (proton) targets are presented. The data were taken the years 2002-2004 2007 with COMPASS spectrometer using a muon beam 160 GeV/c at CERN SPS. provide access to transversity distribution functions, without involving Collins effect as single hadron production. sizeable measured NH_ target indicate non-vanishing u-quark two-hadron...
The COMPASS collaboration at CERN has measured diffractive dissociation of 190 GeV/$c$ pions into the $\pi^-\pi^-\pi^+$ final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins $3\pi$ mass and four-momentum transfer isobar model so far largest PWA consisting 88 waves. narrow $J^{PC} = 1^{++}$ signal is observed $f_0(980)\,\pi$ channel. We present resonance-model study subset spin-density matrix selecting states with 2^{++}$ $4^{++}$ decaying...
We have performed the most comprehensive resonance-model fit of $\pi^-\pi^-\pi^+$ states using results our previously published partial-wave analysis (PWA) a large data set diffractive-dissociation events from reaction $\pi^- + p \to \pi^-\pi^-\pi^+ p_\text{recoil}$ with 190 GeV/$c$ pion beam. The PWA results, which were obtained in 100 bins three-pion mass, $0.5 < m_{3\pi} 2.5$ GeV/$c^2$, and simultaneously 11 reduced four-momentum transfer squared, $0.1 t' 1.0$ $($GeV$/c)^2$, are subjected...
Exclusive production of $\eta\pi^-$ and $\eta'\pi^-$ has been studied with a $191\,\textrm{GeV}/c$ $\pi^-$ beam impinging on hydrogen target at COMPASS (CERN). Partial-wave analyses reveal different odd/even angular momentum ($L$) characteristics in the inspected invariant mass range up to $3\,\textrm{GeV}/c^2$. A striking similarity between two systems is observed for $L=2,4,6$ intensities (scaled by kinematical factors) relative phases. The known resonances $a_2(1320)$ $a_4(2040)$ are line...
The COMPASS experiment at the CERN SPS has studied diffractive dissociation of negative pions into π−π−π+ final state using a 190 GeV/c pion beam hitting lead target. A partial wave analysis been performed on sample 420 000 events taken values squared 4-momentum transfer t′ between 0.1 and 1 GeV2/c2. well-known resonances a1(1260), a2(1320), π2(1670) are clearly observed. In addition, data show significant natural-parity exchange production resonance with spin-exotic quantum numbers JPC=1−+...
A semi-inclusive measurement of charged hadron multiplicities in deep inelastic muon scattering off an isoscalar target was performed using data collected by the COMPASS Collaboration at CERN. The following kinematic domain is covered data: photon virtuality ${Q}^{2}>1\text{ }\text{ }(\mathrm{GeV}/c{)}^{2}$, invariant mass hadronic system $W>5\text{ }\mathrm{GeV}/{c}^{2}$, Bjorken scaling variable range $0.003<x<0.4$, fraction virtual energy carried $0.2<z<0.8$, and square transverse...
The COMPASS collaboration has collected the currently largest data set on diffractively produced ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ final states using a negative pion beam of $190\text{ }\text{ }\mathrm{GeV}/c$ momentum impinging stationary proton target. This allows for systematic partial-wave analysis in 100 bins three-pion mass, $0.5<{m}_{3\ensuremath{\pi}}<2.5\text{ }\mathrm{GeV}/{c}^{2}$, and 11 reduced four-momentum...
Nucleation of vortices in units one quantum has been observed with c.w. NMR a rotating cylinder filled 3He-B. During acceleration new vortex is created each time the counterflow velocity at perimeter reaches critical value vc(T, p). The measured vc resembles calculated vcb(T, p) bulk superflow instability, but smaller by factor power law dependence on superfluid coherence length. This indicates that nucleation event takes place whenever flow exceeds vcb locally site and barrier vanishes.
We present a precise measurement of the deuteron longitudinal spin asymmetry A1d and spin-dependent structure function g1d at Q2<1(GeV/c)2 4×10−5<x<2.5×10−2 based on data collected by COMPASS experiment CERN during years 2002 2003. The statistical precision is tenfold better than that previous in this region. measured are found to be consistent with zero whole range x.
We present a determination of the gluon polarisation Δg/g in nucleon, based on longitudinal double-spin asymmetry DIS events with Q2>1(GeV/c)2 including pair large transverse-momentum hadrons final state. The data were obtained by COMPASS experiment at CERN using 160 GeV/c polarised muon beam scattering off LiD6 target. is evaluated Neural Network approach for three intervals momentum fraction xg covering range 0.04<xg<0.27. values leading order QCD do not show any significant dependence xg....
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...
Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented three-dimensional bins the Bjorken scaling variable x, relative virtual-photon energy y, and fraction z carried by produced hadron. data obtained COMPASS Collaboration 160 GeV muons off an isoscalar 6LiD target. They cover kinematic domain 1(GeV/c)2<Q2<60(GeV/c)2 photon virtuality, 0.004<x<0.4, 0.1<y<0.7, 0.20<z<0.85, W>5 GeV/c2 invariant mass hadronic system. from sum...