- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Black Holes and Theoretical Physics
- Radiation Detection and Scintillator Technologies
- Computational Physics and Python Applications
- Algorithms and Data Compression
- Atomic and Subatomic Physics Research
- Particle Accelerators and Free-Electron Lasers
- Noncommutative and Quantum Gravity Theories
- Markov Chains and Monte Carlo Methods
- Energy Efficiency and Management
- Nuclear Physics and Applications
- Distributed and Parallel Computing Systems
- Radioactive Decay and Measurement Techniques
- Radio Astronomy Observations and Technology
- Flexible and Reconfigurable Manufacturing Systems
- Stochastic processes and statistical mechanics
- Manufacturing Process and Optimization
- Radiation Therapy and Dosimetry
TU Dortmund University
2024-2025
University of Engineering & Management
2025
University of Chicago
2004-2013
Fermi National Accelerator Laboratory
1998-2012
European Organization for Nuclear Research
2012
University College London
2002-2004
FH Aachen
2002-2004
University of Liverpool
2001-2004
Manchester University
2004
University of Debrecen
2004
We report test beam studies of 11% the production ATLAS Tile Calorimeter modules. The modules were equipped with front-end electronics and all calibration systems planned for final detector. used muon, electron hadron beams ranging in energy from 3 to 350 GeV. Two independent showed that light yield calorimeter was ∼70pe/GeV, exceeding design goal by 40%. Electron provided a at electromagnetic scale. Over 200 cells variation response 2.4%. linearity also measured. Muon an intercalibration...
A search for single top quark production via flavour changing neutral currents (FCNC) was performed with data collected by the OPAL detector at e+e− collider LEP. Approximately 600 pb−1 of s=189–209 GeV were used to FCNC process e+e−→tc(u)→bWc(u). This analysis is sensitive leptonic and hadronic decay modes W boson. No evidence a observed. Upper limits 95% confidence level on cross-section as function centre-of-mass energy are derived. Limits anomalous coupling parameters κγ κZ determined...
We report here the first observation of directed flow ($v_1$) hypernuclei $^3_{\Lambda}$H and $^4_{\Lambda}$H in mid-central Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 3 GeV RHIC. These data are taken as part beam energy scan program carried out by STAR experiment. From 165 million good events 5-40% centrality, about 8400 5200 candidates reconstructed through two- three-body decay channels. observe that these exhibit significant flow. Comparing to light nuclei, it is found mid-rapidity $v_1$...
A search for the single production of doubly-charged Higgs bosons is performed using e+e− collision data collected by OPAL experiment at centre-of-mass energies between 189 GeV and 209 GeV. No evidence existence H±± observed. Upper limits are derived on hee, Yukawa coupling to like-signed electron pairs. 95% confidence level upper limit hee< 0.071 inferred M(H±±)<160 assuming that sum branching fractions all lepton flavour combinations 100%. Additionally, indirect constraints hee from Bhabha...
This letter describes a direct search for pair produced magnetic monopoles in e+e- collisions. The analysis is based on 62.7 pb^-1 of data collected with the OPAL detector at an average centre-of-mass energy sqrt(s)= 206.3GeV. monopole signal was assumed to be characterized by two back-to-back particles anomalously high ionization loss de/dx tracking chambers. No evidence production observed. Upper limits were obtained pair-production cross-section (sigma) mass range 45 GeV/c^2
Non-commutative QED would lead to deviations from the Standard Model depending on a new energy scale Lambda_NC and unique direction in space defined by two angles eta xi. Here this analysis is as angle between rotation axis of earth. The predictions such theory for process e+e- -> gamma are evaluated specific orientation OPAL detector compared measurements. Distributions polar azimuthal scattering used extract limits model parameter eta. At 95% confidence level found be larger than 141 GeV...
A study of W+W- events accomanied by hard photon radiation produced in e+e- collisions at LEP is presented. Events consistent with being two on-shell W bosons and an isolated are selected from 681 pb^-1 data recorded 180 GeV < sqrt(s) 209 GeV. For these data, 187 candidates energies greater than 2.5 The used to determine the W+ W- gamma cross section five values sqrt(s). results Standard Model expectation. These provide constraints on related O(alpha) systematic uncertainties measurement...
We present the first experimental results based on jet boost algorithm, a technique to select unbiased samples of gluon jets in ${e}^{+}{e}^{\ensuremath{-}}$ annihilations, i.e. free biases introduced by event selection or finding criteria. Our are derived from hadronic ${Z}^{0}$ decays observed with OPAL detector at LEP collider CERN. First, we test algorithm through studies HERWIG Monte Carlo events and find that it provides accurate measurements charged particle multiplicity distributions...
Hadronic final states with a hard isolated photon are studied using data taken at centre-of-mass energies around the mass of Z boson OPAL detector LEP. The strong coupling αs is extracted by comparing and QCD predictions for event shape observables average reduced ranging from 24 GeV to 78 GeV, energy dependence studied. Our results consistent running as predicted show that within uncertainties our analysis shapes in hadronic decays radiation can be described energies. Combining all values...
The inclusive branching ratio for the process b→τ−ν̄τX has been measured using hadronic Z decays collected by OPAL experiment at LEP in years 1992–2000. result is: BR(b→τ−ν̄τX)=(2.78±0.18±0.51)%. This measurement is consistent with Standard Model expectation and puts a constraint of tanβ/MH±<0.53 GeV−1 95% confidence level on Type II Two Higgs Doublet Models.
The hadronic structure function of the photon F2γ(x,Q2) is measured as a Bjorken x and virtuality Q2 using deep-inelastic scattering data taken by OPAL detector at LEP e+e− centre-of-mass energies from 183 to 209 GeV. Previous measurements dependence F2γ are extended an average 〈Q2〉=780 GeV2 in kinematic range 0.15<x<0.98. evolution studied for 12.1<〈Q2〉<780 three ranges x. As predicted QCD, show positive scaling violations with F2γ(Q2)/α=(0.08±0.02+0.05−0.03)+(0.13±0.01+0.01−0.01)lnQ2,...
We present a determination of the LEP beam energy using "radiative return" fermion-pair events recorded at centre-of-mass energies from 183 GeV to 209 GeV. find no evidence disagreement between OPAL data and Energy Workings Group's standard calibration. Including energy- averaged 11 MeV uncertainty in determination, we obtain is higher than that obtained calibration by 0+-34(stat.)+-27(syst.)MeV
We present the results of an upgrade to D0 muon system. Scintillating counters have been added existing central system provide rejection for cosmic ray muons and out-of-time background, additional fast timing information in upgraded Tevatron. Performance from 1994-1996 Tevatron run are presented.
Events with a final state consisting of two or more photons and large missing transverse energy have been observed in e+e- collisions at centre-of-mass energies the range 192 - 209 GeV using OPAL detector LEP. Cross-section measurements are performed within kinematic acceptance selection compared expectation from Standard Model process -> nu gamma gamma(gamma). No evidence for new physics contributions to this is observed. Upper limits on sigma (e+e- XX) BR^2(X Ygamma) derived case stable...