Search results for "Deute"
showing 10 items of 549 documents
Quark effects, meson-exchange currents and background in the d(e,e'p)delta reaction
1994
[EN] We have studied in detail the cross section for the d(e, e'p)Delta reaction leading to the emission of a fast nucleon and a Delta at rest, which has been advocated as a tool to investigate quark effects in nuclei. We find that ordinary meson-exchange currents mechanisms dominate the quark-exchange effects in the region of excitation of the Delta and could be competitive at higher energies. Furthermore, at these higher energies, the small cross sections for the quark signal, together with the presence of a background about one order of magnitude bigger than the quark signal, make in any case the extraction of information about quark-exchange currents effects extraordinarily difficult.
Hadron azimuthal distributions and transverse spin asymmetries in DIS of leptons off transversely polarized targets from SMC
1999
Abstract Azimuthal distributions of hadrons (mainly π + and π − ) produced in DIS off transversely polarized targets (proton and deuteron) are studied for the first time in SMC. From these azimuthal distributions, transverse single-spin asymmetries are derived. According to Collins (‘Collins effect’), the azimuthal distribution of the leading hadron might exhibit an symmetry which originates from the transverse polarization of the final quark.
Transverse spin asymmetries in p ↑ p → π± + X and lp ↑ → l′ + π± + X
2000
Abstract While transverse spin effects have been studied in hadronic interactions since a few decades, investigations with leptonic probes have started very recently. Azimuthal distributions of hadrons (mainly π + and π − ) produced in DIS off transversely polarized targets (proton and deuteron) are studied for the first time in SMC. According to Collins (‘Collins effect’), the azimuthal distribution of the leading hadron might exhibit an asymmetry which originates from the transverse polarization of the final quark.
Measurement of Long-Range Angular Correlation and Quadrupole Anisotropy of Pions and (Anti)Protons in Centrald+AuCollisions atsNN=200GeV
2015
We present azimuthal angular correlations between charged hadrons and energy deposited in calorimeter towers in central d+Au and minimum bias p+p collisions at sqrt[s_{NN}]=200 GeV. The charged hadron is measured at midrapidity |η| 2.75 is observed in d+Au collisions. Using the event plane method applied to the Au-going energy distribution, we extract the anisotropy strength v_{2} for inclusive charged hadrons at midrapidity up to p_{T}=4.5 GeV/c. We also present the measurement of v_{2} for identified π^{±} and (anti)protons in central d+Au collisions, and observe a mass-ordering pattern similar to that seen in heavy-ion collisions. These results are compared with viscous hydrodynamic calc…
Precision measurement of structure function ratios for $^{6}$Li, $^{12}$C and $^{40}$Ca
1992
The structure function ratiosF2C/F2Li,F2Ca/F2Li andF2Ca/F2C were measured in deep inelastic muonnucleus scattering at an incident muon energy of 90 GeV, covering the kinematic range 0.0085<x<0.6 and 0.8<Q2<17GeV2. The sensitivity of the nuclear structure functions to the size and mean density of the target nucleus is discussed.
Measurement of Helicity-Dependent Photoabsorption Cross Sections on the Neutron from 815 to 1825 MeV
2005
Helicity-dependent total photoabsorption cross sections on the deuteron have been measured for the first time at ELSA (Bonn) in the photon energy range from 815 to 1825 MeV. Circularly polarized tagged photons impinging on a longitudinally polarized LiD target have been used together with a highly efficient 4pi detector system. The data around 1 GeV are not compatible with predictions from existing multipole analyses. From the measured energy range an experimental contribution to the GDH integral on the neutron of [33.9 +/- 5.5(stat) +/- 4.5(syst)] microb is extracted.
Laser spectroscopy of light muonic atoms and the nuclear charge radii
2021
The energy levels of hydrogen-like atomic systems are shifted slightly by the complex structure of the nucleus, in particular by the finite size of the nucleus. These energy shifts are vastly magnified in muonic atoms and ions, i.e. the hydrogen-like systems formed by a negative muon and a nucleus. By measuring the 2S-2P energy splitting in muonic hydrogen, muonic deuterium and muonic helium, we have been able to deduce the p, d, ^33He and ^44He nuclear charge radii to an unprecedented accuracy. These radii provide benchmarks for hadron and nuclear theories, lead to precision tests of bound-state QED in regular atoms and to a better determination of the Rydberg constant.
Role of pion exchange inηmeson photoproduction on the deuteron
2015
Incoherent $\ensuremath{\eta}$ photoproduction on the deuteron is studied, with the main emphasis on the role of final-state interactions. In addition to the previously studied mechanisms of $NN$ and $\ensuremath{\eta}N$ rescatterings, the role of an intermediate pion exchange is considered in detail, where first a pion is photoproduced on one nucleon and then rescatters into an $\ensuremath{\eta}$ meson on the other, the spectator nucleon. It is found that the role of this pion-mediated contribution is comparable in size to that of $\ensuremath{\eta}N$ rescattering. Results for total and semi-inclusive differential cross sections and associated polarization observables are presented. In pa…
Translational and rotational diffusion in supercooled orthoterphenyl close to the glass transition
1992
Self diffusion coefficients in supercooled orthoterphenyl (OTP) have been determined down toD t =3·10−14 m2s−1 using a1H-NMR technique applying static field gradients up to 53T m−1 In a range of more than two decades theD t values agree with those of photochromic tracer molecules of the same size determined by forced Rayleigh scattering down to the glass transition temperatureT g . A change of mechanism is found for translational diffusion atT c ≈1.2T g whereD t is proportional to the inverse shear viscosityη −1 atT>T c butD t ∼η ξ with ξ=0.75 atT<T c . Rotational correlation times determined by2H-NMR stimulated echo techniques in deuterated OTP remain proportinal toη −1 down toT g . Our re…
A three-body calculation of incoherent $\pi^0$ photoproduction on a deuteron
2019
Incoherent $\pi^0$ photoproduction on a deuteron in the $\Delta(1232)$ region is treated in a three-body scattering approach using separable two-body interactions. Results are presented for total and differential cross sections. It turns out that the role of higher order terms beyond the first order in the multiple scattering series is insignificant, and their inclusion cannot explain the existing discrepancy between theory and experiment.