Measurements of the electric and magnetic form factors of the neutron and their dependence on inelastic modeling

The charge and magnetic elastic form factors of the neutron, GEn(Q2) and GMn(Q2), have been measured in the four-momentum transfer range 1.75 < Q2 < 4.00 (GeV/c )2 using a Rosenbluth separation. These measurements constitute part of performed at the End Station A experiment NE11 which was facilities at the Stanford Linear Accelerator Center in the winter of 1989. The results show that GMn(Q2)/μn, GD(Q2) is consistent with unity, where μn, is the neutron anomalous magnetic moment, and GD(Q2) = (1.0 + Q2/0.71) -2, is the empirical dipole formula. The results for (GEn(Q2)/GD(Q2)) are consistent with zero within errors. The extraction of the neutron electromagnetic form factors from deuterium cross sections is a model dependent procedure because of the Fermi momentum of the bound nucleons. In addition to the smeared quasielastic cross section, there is an inelastic tail due to pion production which extends into the quasielastic region. This tail is significant and must be subtracted to measure the neutron form factors. An extensive study has been made on the effect of the modeling of this tail on the measured form factors using different Fermi smearing models, off-mass-shell corrections, and deuteron wave functions. The off-mass-shell-effects were the largest, but still smaller than the experimental error. Comparisons were made with many theoretical models. Measurements were also obtained of the Δ(1232) resonance transition form factors in the range 1.6 < Q2 < 6.75 (GeV/c)2