The deuteron: structure and form factors

A brief review of the history of the discovery of the deuteron in provided. The current status of both experiment and theory for the elastic electron scattering is then presented.Comment: 80 pages, 33 figures, submited to Advances in Nuclear Physic

The He-4(e, e ' p) cross section at high missing energies

The He-4(e, e' p) reaction has been studied in a kinematic regime in which short-range correlations are expected to have a strong impact on the reaction strength. The measured cross sections exhibit a bump-shaped structure at missing energies corresponding to quasi-free knockout of two nucleons. The results of microscopic calculations, that account for meson-exchange currents, intermediate Delta -excitation and final-state interactions, reproduce the data satisfactorily. The calculations indicate that at small proton emission angles the cross section is dominated by knockout of a correlated nucleon pair.

Relativistic effects in the electrodisintegration of deuterium

The structure function R(LT) and the cross-section asymmetry A(phi) with respect to the direction of the momentum transfer in the reaction H-2(e, e'p) have been measured at a four-momentum transfer squared of 0.2 (GeV/c)(2), for missing momenta between 160 and 220 MeV/c at an invariant mass of 1050 MeV. For a proper description of these data calculations that include a relativistic form of the nucleon current operator are favoured. The absolute 2H(e, e'p) cross-section data favour a covariant calculation over non-relativistic calculations with relativistic corrections

Deuteron electrodisintegration at high missing momenta

The reaction (2)H(e, e'p) has been studied at an invariant mass W of 1050 MeV, i.e. well below the Delta(1232) resonance, Cross sections have been obtained at values of Q(2), the four-momentum transfer squared, of 0.10, 0.20, and 0.28 (GeV/c)(2), covering a missing-momentum range from 150 to 700 MeV/c. The data are compared to the results of covariant calculations of Tjon, and the results of calculations based on a Schrodinger formalism due to Laget and the Mainz group, respectively. The data are well described by the calculations of the Mainz group, whereas they are underestimated by Tjon's calculations at high missing momenta. The calculations of Laget, on the other hand, overestimate the data at low missing momenta, but give a good account of the data at high missing momenta. More detailed considerations reveal that the Delta(1232) contributions are dominant at high missing momenta. However, the lacking Delta(1232) contribution in Tjon's calculations is not enough to explain the large discrepancy between his calculation and the present (2)H(e, e'p) data at high missing momentum. Probably the deuteron wave function employed in the covariant calculations has a D-state contribution that is too small

Deuteron electrodisintegration in the Delta-resonance region

The differential cross section and the transverse-transverse interference structure function for the reaction H-2(e,e'p)n have been determined at an np invariant mass of 2.16 GeV. The data, covering a 40 degrees range in the proton emission angle, indicate that Delta excitation and subsequent N Delta interaction is the dominant reaction mechanism. Calculations performed within an N Delta coupled-channel approach reproduce the cross section data, but underestimate the f(TT) results by 30 to 40 percent

Proton detection with large-acceptance scintillator detection systems in electron-scattering environments

Two highly segmented plastic-scintillator arrays have been developed for proton detection in electron scattering experiments. The detectors subtend solid angles of 225 and 550 msr and cover energy ranges of 50-225 and 25-165 MeV, respectively. The charge and arrival time of each photomultiplier signal are digitized by flash ADCs and temporarily stored in a dual-port memory. The readout parameters are computer controlled, tuned, and monitored. These detectors have been employed in (e, e'p) and (e, e'pp) experiments for proton emission angles greater than 30 degrees and for luminosities up to 10(36) nucleons cm(-2) s(-1). The singles counting rates in the scintillator elements of the first layers were about 0.5 x 10(6) particles s(-1) and the trigger rate 1 MHz. The measured resolution in the excitation energy and timing spectra are 2.7% and 0.7 ns, respectively. (C) 1999 Elsevier Science B.V. All rights reserved

Search for Nucleon-nucleon Correlations in the Proton Spectral-function of Pb-208

Cross sections for the reaction Pb-208 (e,e'p) have been measured with the continuous electron beam from the Amsterdam Pulse-Stretcher facility at NIKHEF-K. The spectral function has been extracted for protons with initial momenta of 300 to 500 MeV/c and binding energies up to 26 MeV. The data are compared to calculations with and without inclusion of nucleon-nucleon correlations. Mean-field predictions significantly underestimate the data and the discrepancy increases with binding energy. For transitions to the valence states the discrepancy is removed by introducing long-range correlations. Above the two-nucleon emission threshold long-range and short-range correlations reduce the discrepancy, but are insufficient to fully account for the measured strength

High resolution O-16(gamma*,pi(-)p) experiment

The reaction O-16(gamma*, pi(-)p) was studied with high energy resolution in the region of the Delta resonance at the AmPS facility of NIKHEF. Photoproduction cross sections were extracted for 1p(1/2) and 1p(3/2) neutrons in O-16 and the resulting pion and proton angular distributions are compared to model calculations by Lee, Wright, and Bennhold. The proton angular distributions are well described by the nonlocal version of the model and allow one to extract rms radii and spectroscopic factors for the 1p(1/2) and 1p(3/2) neutron shells. The same calculations are in fair agreement with the pion angular distributions. [S0556-2813(98)05812-9]