Extended Superscaling of Electron Scattering from Nuclei

An extended study of scaling of the first and second kinds for inclusive electron scattering from nuclei is presented. Emphasis is placed on the transverse response in the kinematic region lying above the quasielastic peak. In particular, for the region in which electroproduction of resonances is expected to be important, approximate scaling of the second kind is observed and the modest breaking of it is shown probably to be due to the role played by an inelastic version of the usual scaling variable.Comment: LaTeX, 36 pages including 5 color postscript figures and 4 postscript figure

Superscaling of Inclusive Electron Scattering from Nuclei

We investigate the degree to which the concept of superscaling, initially developed within the framework of the relativistic Fermi gas model, applies to inclusive electron scattering from nuclei. We find that data obtained from the low energy loss side of the quasielastic peak exhibit the superscaling property, i.e., the scaling functions f(\psi') are not only independent of momentum transfer (the usual type of scaling: scaling of the first kind), but coincide for A \geq 4 when plotted versus a dimensionless scaling variable \psi' (scaling of the second kind). We use this behavior to study as yet poorly understood properties of the inclusive response at large electron energy loss.Comment: 33 pages, 12 color EPS figures, LaTeX2e using BoxedEPSF macros; email to [email protected]

Bloom-Gilman duality of inelastic structure functions in nucleon and nuclei

The Bloom-Gilman local duality of the inelastic structure function of the proton, the deuteron and light complex nuclei is investigated using available experimental data in the squared four-momentum transfer range from 0.3 to 5 (GeV/c)**2. The results of our analysis suggest that the onset of the Bloom-Gilman local duality is anticipated in complex nuclei with respect to the case of the protonand the deuteron. A possible interpretation of this result in terms of a rescaling effect is discussed with particular emphasis to the possibility of reproducing the damping of the nucleon-resonance transitions observed in recent electroproduction data off nuclei.Comment: revised version, to appear in Physical Review

Q sup 2 and A dependence of. Delta. (1232) electroexcitation in nuclei

Inclusive electron scattering measurements from SLAC of {Delta} electroexcitation in nuclei are presented. Electrons with energies of 0.96, 1.1, 1.3 and 1.5 GeV were scattered from H, {sup 4}He, C, Fe and W at 37.5{degree} and detected with the End Station A 1.6 GeV/c spectrometer. Q{sup 2} at the {Delta} peak ranged from 0.2 to 0.5 (GeV/c{sup 2}). For all nuclear targets the {Delta} peak position shifts for higher invariant mass as Q{sup 2} increases and in all but one case is above that of the free nucleon. Cross sections have been fitted by the form {sigma} = cA{sup b}. For the {Delta} region b varies from 0.99 to 1.02 with uncertainties of {plus minus}0.01. For the dip region A dependence is observed that is consistent with the effects of Fermi broadening of the quasielastic and {Delta} peaks. Transverse form factors have been calculated and fitted by the function 1/(1 + Q{sup 2}/{Lambda}{sup 2}). The A and invariant mass dependences of {Lambda} are discussed. 22 refs., 6 figs., 1 tab

New measurements of 2^{2}H(γ⃗\vec \gamma,p)n and spin problems in coupled NΔ\Delta/NN interactions

New precision measurements of the 2H(γ→,p)n reaction taken with tagged polarized photons, and covering a wide angular range, are presented for incident energies between 113 and 315 MeV. In the region of the Δ resonance, the photodisintegration observables can potentially be used to probe the NΔ interaction. Coupled-channel calculations are in agreement with cross sections measured with linear polarization parallel to the reaction plane but fail to account for data taken with perpendicular kinematics

PHYSICS WITH POLARIZED PHOTONS

De nouveaux résultats préliminaires sur la photodesintégration du deuton réalisée avec LEGS sont présentés. Les activités expérimentales avec LADON sont rapidement passées en revue. Quelques indications sont données sur des activités possibles avec GRAAL.New preliminary results on the deuteron photodisintegration at LEGS are presented. The experimental activity at LADON is rapidly reviewed and some indication is given for the possible activity at GRAAL