248 research outputs found
Measurement of kinematic and nuclear dependence of R = σ_L/σ_T in deep inelastic electron scattering
We report results on a precision measurement of the ratio R=σ_L/σ_T in deep inelastic electron-nucleon scattering in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤10 (GeV/c)^2. Our results show, for the first time, a clear falloff of R with increasing Q^2. Our R results are in agreement with QCD predictions only when corrections for target mass effects and some additional higher twist effects are included. At small x, the data on R favor structure functions with a large gluon contribution. We also report results on the differences R_A-R_D and the cross section ratio σ^A/σ^D between Fe and Au nuclei and the deuteron. Our results for R_A-R_D are consistent with zero for all x, Q^2 indicating that possible contributions to R from nuclear higher twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The ratios σ^A/σ^D from all recent experiments, at all x, Q^2 values, are now in agreement
Measurement of the Difference in R=σ_L/σ_T and of σ^A/σ^D in Deep-Inelastic e-D, e-Fe, and e-Au Scattering
We measured the differences in R=σ_L/σ_T and the cross-section ratio σA/σD in deep-inelastic electron scattering from D, Fe, and Au nuclei in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤5 (Gev/c)^2. Our results for R^A-R^D are consistent with zero for all x and Q^2, indicating that possible contributions to R from nuclear higher-twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The European Muon Collaboration effect is reconfirmed, and the low-x data from all recent experiments, at all Q^2, are now in agreement
Longitudinal and Transverse Response Functions in ^(56)Fe(e,e') at Momentum Transfer near 1 GeV/c
Inclusive electron-scattering cross sections have been measured for ^(56)Fe in the quasielastic region at electron energies between 0.9 and 4.3 GeV, at scattering angles of 15° and 85°. Longitudinal and transverse response functions at a q of 1.14 GeV/c have been extracted using a Rosenbluth separation. The experimental Coulomb sum has been obtained with aid of an extrapolation. The longitudinal response function, after correction for Coulomb distortion, is lower than quasifree-scattering-model predictions at the quasielastic peak and on the high-ω side
y scaling in electron-nucleus scattering
Data on inclusive electron scattering from A = 4, 12, 27, 56, 197 nuclei at large momentum transfer are presented and analyzed in terms of y scaling. We find that the data do scale for y 1), and we study the convergence of the scaling function with the momentum transfer Q^2 and A
Calculation of energy levels and transition amplitudes for barium and radium
The radium atom is a promising system for studying parity and time invariance
violating weak interactions. However, available experimental spectroscopic data
for radium is insufficient for designing an optimal experimental setup. We
calculate the energy levels and transition amplitudes for radium states of
significant interest. Forty states corresponding to all possible configurations
consisting of the , and single-electron states as well as the
states of the , and configurations have been calculated.
The energies of ten of these states corresponding to the , ,
, and configurations are not known from experiment. Calculations
for barium are used to control the accuracy.Comment: 12 pages, 4 table
Measurement of tensor analyzing powers in deuteron photodisintegration
New accurate measurement of tensor analyzing powers T20, T21 and T22 in
deuteron photodisintegration has been performed. Wide-aperture non-magnetic
detectors allowed to cover broad kinematic ranges in a single setup: photon
energy = 25 to 600 MeV, proton emission angle in CM = 24 to 48 deg. and 70 to
102 deg. New data provide a significant improvement of a few existing
measurements. The angular dependency of the tensor asymmetries in deuteron
photodisintegration is extracted for the first time.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let
Two-Body Photodisintegration of the Deuteron up to 2.8 GeV
Measurements were performed for the photodisintegration cross section of the deuteron for photon energies from 1.6 to 2.8 GeV and center-of-mass angles from 37° to 90°. The measured energy dependence of the cross section at θc.m. = 90° is in agreement with the constituent counting rules
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