Search results for "nuclear physics"
showing 10 items of 5307 documents
Backward production of mesons associated with? ++(1232) in? + p interactions at 20 GeV/c
1991
We have analyzed backward meson production inπ + p reactions at 20GeV/c, which were measured in the CERN Ω spectrometer triggered by a fast proton (p f ), in experiment WA56. Production via baryon exchange of quasi-two-body final statesΔ ++ (1232)ρ 0 (770),Δ ++ (1232)f 2 (1270), andΔ ++ (1232)ρ 3 0 (1690) is clearly identified. The density matrix elements of meson resonances and ofΔ ++ (1232) are analyzed. We have observed also the reactionsπ + p→Δ ++ (1232)π 0 andπ + p→Δ ++ (1232)ω in thep f π + π 0 andp f π + π + π − π 0 final states.
Tau-spin correlations at the z-peak: aplanarities of the decay products
1991
8 páginas, 3 figuras, 1 tabla.-- CERN-TH-5932-90 ; FTUV-90-26.
Observation of meson central production in baryon exchange processes
1991
The central production of ρ0,f2 and ρ30 mesons is observed for the first time in processes which are originated by π+p reactions proceeding via baryon exchange mechanism. The data come from the CERN WA56 experiment designed to separate the baryon exchange reactions in π+p-collisions at 20 GeV/c. We report on the measured integral and differential cross sections and also give the density matrix elements of the meson resonances observed.
Quadrupole deformation of Xe-130 measured in a Coulomb-excitation experiment
2020
Physical review / C 102(5), 054304 (2020). doi:10.1103/PhysRevC.102.054304
Measurement of the inelastic proton-proton cross-section at √s = 7 TeV with the ATLAS detector
2011
The dependence of the rate of proton–proton interactions on the centre-of-mass collision energy, √s, is of fundamental importance for both hadron collider physics and particle astrophysics. The dependence cannot yet be calculated from first principles; therefore, experimental measurements are needed. Here we present the first measurement of the inelastic proton–proton interaction cross-section at a centre-of-mass energy, √s, of 7 TeV using the ATLAS detector at the Large Hadron Collider. Events are selected by requiring hits on scintillation counters mounted in the forward region of the detector. An inelastic cross-section of 60.3±2.1 mb is measured for ξ>5×10[superscript −6], where ξ is ca…
Levels of 188Re nucleus populated in thermal neutron capture reaction
2016
Abstract Levels of 188 Re populated in thermal neutron capture reaction with enriched 187 Re targets have been studied. Single γ -ray spectrum of 188 Re, measured with the high-resolution crystal diffraction spectrometer GAMS5, as well as γγ -coincidence experiments performed with high efficiency Ge detectors, allowed to develop model-independent level scheme of the doubly-odd 188 Re nucleus up to ∼ 1.5 MeV excitation energy. Analysis of the established 188 Re level scheme in terms of the quasiparticle-plus-rotor model indicates coexistence of axially-deformed and triaxial structures in the energy range above 400 keV.
Diffractive vector meson production in ultraperipheral heavy ion collisions from the Color Glass Condensate
2014
We compute cross sections for incoherent and coherent diffractive J/$\Psi$ and $\Psi(2S)$ production in ultraperipheral heavy ion collisions. The dipole models used in these calculations are obtained by fitting the HERA deep inelastic scattering data and compared with available electron-proton diffraction measurements. We obtain a reasonably good description of the available ALICE data. We find that the normalization of the ultraperipheral cross section has large model dependence, but the rapidity dependence is more tightly constrained.
Hard single diffraction in p̄p collisions at s=630 and 1800 GeV
2002
Using the D empty set detector, we have studied events produced in (p) over barp collisions that contain large forward regions with very little energy deposition ("rapidity gaps") and concurrent jet production at center-of-mass energies of roots = 630 and 1800 GeV. The fraction of events with forward or central jets associated with rapidity gaps is compared to predictions for hard diffraction. We also extract the momentum loss for scattered protons in such processes. (C) 2002 Elsevier Science B.V. All rights reserved.
First Measurement of Transverse-Spin-Dependent Azimuthal Asymmetries in the Drell-Yan Process
2017
The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/$c$, $\pi^{-}$ beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/$c^2$ and 8.5 GeV/$c^2$. The observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of Quantum Chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic sc…
Nuclear modification of forward Drell-Yan production at the LHC
2017
Forward Drell-Yan production at high energy can provide important constraints on gluon densities at small $x$, in the saturation regime. In this work we focus on the nuclear modification of this process, which could be measured at the LHC in the near future. For this we employ the color dipole approach, using the optical Glauber model to relate the dipole cross section of a nucleus to the one of a proton. Combining these results with our earlier results for forward $J/\psi$ production, we compute the ratio of the nuclear modification factors of these two processes. This observable was recently suggested as a way to distinguish between initial and final state effects in forward particle prod…