Fig. 10 shows the kinematic range in and . The region below the dashed (solid) curve is what is accessible with 4 (6) GeV beam at JLab ( in both cases). Experiment E89-008 did not cover the full range for very large values, so the existing data for is limited to GeV. Previous SLAC measurements of inclusive electron scattering from nuclei [1] were limited to and . The same measured cross sections will then be examined as a function of the scaling variable and . Fig. 11 shows the kinematic range in and . Again, the dashed curve is what can be measured with 4 GeV beam, and the solid curve represents the coverage available with a 6 GeV beam. An addition to the measurement since the original proposal in 1994 is the inclusion of He and He cryogenic targets. The proposed data will significantly increase the coverage for He and He compared to earlier SLAC measurements [42,1].
The increase in beam energy to 6 GeV will have the greatest impact on the range for kinematic points with . This extended data is critical to studies of the transition from scattering from nucleons to scattering from quarks as described in the introduction. At larger values of , the increase is smaller, but is crucial for studies of the nature of the short range correlations. While the increase is not as large as for the lower values, it is enough to allow us to reach well into the scaling region ( GeV) out to extremely large values. The 4 GeV measurement only reached GeV for , and while the coverage for iron was much better for , the deuterium data in this region was quite limited. The increased range for large corresponds to a similar increase in for large negative values of allowing direct study of the approach to the scaling limit, as well as data in the scaling region for extremely large values of . This high (large negative ) region is very important in determining if the high momentum components are explained by two nucleon correlations or if large multinucleon correlations are required.
A beam energy of 6 GeV is sufficient to reach the scaling limit for the highest values of (), and energies above 6 GeV do not significantly improve the coverage for these very large values of . Higher beam energies would have the most improvement in kinematic coverage for . However, the higher values accessible in that region are not necessary for probing nucleon momentum distributions and short range correlations. One may be able to perform ``DIS'' experiments for at extremely high values (where the quasielastic and resonance contributions will disappear even for ). Such an experiment would require energies well above 6 GeV. Thus, we feel that 6 GeV is the most appropriate energy for the proposed measurement.