J. Nystrand
A5103866235- High-Energy Particle Collisions Research
- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Nuclear reactor physics and engineering
- Particle Detector Development and Performance
- Nuclear physics research studies
- Dark Matter and Cosmic Phenomena
- Radiation Detection and Scintillator Technologies
- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Cold Atom Physics and Bose-Einstein Condensates
- Pulsars and Gravitational Waves Research
- Nuclear Physics and Applications
- Stochastic processes and statistical mechanics
- Theoretical and Computational Physics
- Statistical Methods and Bayesian Inference
- Particle Accelerators and Free-Electron Lasers
- Cosmology and Gravitation Theories
- Superconducting Materials and Applications
- Ion-surface interactions and analysis
- Radiation Effects in Electronics
- Atomic and Subatomic Physics Research
- Gamma-ray bursts and supernovae
- Statistical Mechanics and Entropy
- Radioactive Decay and Measurement Techniques
University of Bergen
2016-2025
University of Pavol Jozef Šafárik
2022-2024
A. Alikhanyan National Laboratory
2014-2024
European Organization for Nuclear Research
1994-2023
University of Koblenz and Landau
2023
University of Kaiserslautern
2023
European Council
2023
Lund University
2008-2020
Pontifical Catholic University of Peru
2017
Abilene Christian University
2003-2014
ALICE is a general-purpose heavy-ion experiment designed to study the physics of strongly interacting matter and quark–gluon plasma in nucleus–nucleus collisions at LHC. It currently involves more than 900 physicists senior engineers, from both nuclear high-energy sectors, over 90 institutions about 30 countries.
Moving highly-charged ions carry strong electromagnetic fields that act as a field of photons. In collisions at large impact parameters, hadronic interactions are not possible, and the interact through photon-ion photon-photon known {\it ultra-peripheral collisions} (UPC). Hadron colliders like Relativistic Heavy Ion Collider (RHIC), Tevatron Large (LHC) produce photonuclear two-photon luminosities energies beyond accessible elsewhere; LHC will reach $\gamma p$ energy ten times...
Exclusive vector meson production reactions such as Au+Au$\ensuremath{\rightarrow}\mathrm{Au}+\mathrm{Au}+\mathrm{V},$ where $V=\ensuremath{\rho}, \ensuremath{\omega}, \ensuremath{\varphi}$, or $J/\ensuremath{\psi},$ can proceed through photon-Pomeron and photon-meson interactions. Photons from the electromagnetic field of one nucleus interact coherently with other nucleus. Photonuclear cross sections are scaled $\ensuremath{\gamma}p$ data convoluted photon spectrum to find exclusive rates....
Vector mesons are produced copiously in peripheral relativistic heavy-ion collisions. Virtual photons from one ion can fluctuate into quark-antiquark pairs and scatter the second ion, emerging as vector mesons. The emitter target indistinguishable, so emission two ions will interfere. have negative parity interference is destructive, reducing production of with small transverse momentum. short lived, decay before overlap. However, decay-product wave functions overlap interfere since they an...
Relativistic heavy ions are copious sources of virtual photons. The large photon flux gives rise to a substantial photonuclear interaction probability at impact parameters where no hadronic interactions can occur. Multiple in single collision possible. In this Letter, we use mutual Coulomb excitation both nuclei as tag for moderate-impact-parameter collisions. We calculate the cross section coherent vector-meson production accompanied by and show that median parameter is much smaller than...
We discuss the photoproduction of $\ensuremath{\Upsilon}$ and $J/\ensuremath{\psi}$ at high energy $\overline{p}p$, $pp$, heavy ion colliders. predict large rates in $\overline{p}p$ interactions Fermilab Tevatron $pp$ CERN Large Hadron Collider. The is also produced copiously Relativistic Heavy Ion These reactions can be used to study gluon distribution protons nuclei. show that different $CP$ symmetries initial states lead differences transverse momentum spectra mesons vs collisions.
Highly charged relativistic heavy ions have high cross sections for two-photon interactions. The photon flux is enough that interactions may be accompanied by additional photonuclear Except the shared impact parameter, these are independent. Additional like mutual Coulomb excitation of experimental interest, because neutrons from nuclear dissociation provide a simple, relatively unbiased trigger. We calculate sections, rapidity, mass, and transverse momentum $({p}_{T})$ distributions...
A search for the production of direct photons in S+Au collisions at 200AGeV has been carried out CERN-WA80 experiment. For central measured photon excess each pT, averaged over range 0.5≤pT≤2.5GeV/c, corresponded to 5.0% total inclusive yield with a statistical error σstat=0.8% and systematic σsyst=5.8%. Upper limits on invariant 90% C.L. are presented. Possible implications dynamics high-energy heavy-ion discussed.Received 16 November 1995DOI:https://doi.org/10.1103/PhysRevLett.76.3506©1996...
Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158A GeV. The invariant interferometric radii extracted for 100<K(T)<300 MeV/c and compared to from charged pion correlations. yield soft photons, K(T)<300 MeV/c, was the correlation strength theoretical calculations.
Event-by-event fluctuations in the multiplicities of charged particles and photons, total transverse energy 158AGeV Pb+Pb collisions are studied for a wide range centralities. For narrow centrality bins multiplicity distributions found to be near perfect Gaussians. The effect detector acceptance on has been demonstrated follow statistical considerations. dependence particle measured data agree reasonably well with those obtained from participant model. However, photons have lower compared...
Heavy quarks are copiously produced in ultra-peripheral heavy ion collisions. In the strong electromagnetic fields, c c-bar and b b-bar by photonuclear two-photon interactions; hadroproduction can occur grazing interactions. We present total cross sections, quark transverse momentum rapidity distributions, as well Q Q-bar invariant mass spectra from three production channels. consider AA pA collisions at Relativistic Ion Collider Large Hadron Collider. discuss techniques for separating...
Several hadronic observables have been studied in central $158A \mathrm{GeV}$ Pb+Pb collisions using data measured by the WA98 experiment at CERN: single ${\ensuremath{\pi}}^{\ensuremath{-}}$ and ${K}^{\ensuremath{-}}$ production, as well two- three-pion interferometry. The Wiedemann-Heinz hydrodynamical model has fitted to pion spectrum, giving an estimate of temperature transverse flow velocity. Bose-Einstein correlations between two identified analyzed a function ${k}_{T},$ different...
Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at sqrt[S{NN}]=17.4 GeV midrapidity (2.3 less than or approximately equal eta{lab} 3.0) over the range 0.7 p{T} 3.5 GeV/c. The are compared to pi{0} Pb+Pb sqrt[S{NN}]=17.3 same experiment. For a wide of centralities (N{part} 300), yield pi{0}'s with greater 2 GeV/c is larger consistent yields scaled number nucleon-nucleon (N{coll}), while for central N{part}greater 350, suppressed.
Cross sections are calculated for single and double photon exchange in ultraperipheral Pb$+$Pb collisions at the CERN Large Hadron Collider. The particle production is simulated with DPMJET event generator. cross found around midrapidity, making these processes an important background to hadronic nuclear interactions both trigger analysis levels.
An equation is presented, which allows us to calculate the dependence of multiplicity particles produced in nucleus - collisions, , on an experimentally measured value strongly correlated impact parameter b. The combines data from a wide range projectile masses ( 197) over large momentum region . possible meaning parameters discussed context simple geometrical model.
The mass, energy, and centrality dependence of rapidity density distributions relativistic, charged particles, produced in heavy-ion interactions the energy range 4A–200A GeV, are investigated. results indicate that show systematic variations, which used to predict for Au+Au Pb+Pb a model-independent way.Received 6 April 1992DOI:https://doi.org/10.1103/PhysRevLett.69.745©1992 American Physical Society