Outlook and Open Questions

Precise determination of the neutron electric form factor remains a high priority goal. Knowledge of it, as well as the magnetic form factor, are not only essential for confrontation with hadronic models but are needed for accurate interpretation of other experiments, most notably measurement of parity violation in elastic scattering from the proton. The most promising reactions for measuring appear to be quasi-elastic (e,en) from either polarized deuteron or, at higher , He targets or via measurement of the final state neutron polarization in d(,e). Clearly, CW beams are essential for the success of this coincidence program. Proposals at MIT/Bates and CEBAF are in place that promise precise data over the 0.2-2.0 (GeV/c) range of momentum transfers.

The apparent discrepancy between the isoscalar charge form factors in A=2 and A=3 must be resolved. In particular, a more precise determination of the deuteron monopole form factor, especially the location of the minimum is required. A new measurement of is proposed for CEBAF that should be of greater precision and extend the range of the data to 1.8 (GeV/c). From an experimental point of view, a polarization observable other than would be attractive as a way to bring in different classes of systematic effects. A promising choice is the vector polarization observable . Its experimental determination requires a polarized electron beam and a vector polarized deuterium target. It has the benefit of being obtained in a pure asymmetry measurement (with respect to the two helicity states of the beam) so that it should have rather small systematic errors. Such an experiment is also proposed for CEBAF.

Detailed elucidation of the relevant degrees of freedom (nucleons, mesons, 's) in electro-disintegration of the few-body systems necessitates full exploitation of polarization observables. At low , the combination of polarized deuterium and helium internal targets at MIT/Bates, along with a large acceptance detector (BLAST) would allow, e.g., the determination of spin-dependent momentum distributions in these systems. In addition, spin asymmetries in electro-pion production appear to be a powerful tool for addressing the isobar content of nuclear wavefunctions. Spin transfer reactions, i.e., d(,e) in non-quasifree kinematics are also expected to be quite sensitive to small components of the reaction mechanism. Such measurements, already underway at MIT/Bates and planned for CEBAF, demand polarized CW beams of significant intensity to overcome small cross sections and polarimeter efficiencies.