Data on inclusive electron scattering from A =4, 12, 27, 56, 197 nuclei at large momentum transfer are presented and analyzed in terms of y scaling. We find that the data do scale for y < 0 (x > 1 ), and we study the convergence of the scaling function with the momentum transfer Q 2 and A.PACS numbers: 25.30.Fj The nuclear response function measured by inclusive quasielastic electron-nucleus scattering is an important observable in the study of the wave function of the bound nuclear system and the properties of its constituents. In the impulse approximation (lA) it relates the inclusive cross sections to the free electron-nucleon cross sections aep and a en• and to the spectral function 1 p(k, E) which gives the probability to find a nucleon in the nucleus with momentum k and separation energy E. On general grounds, the inclusive cross section a(q, ro) depends on electron energy loss ro and momentum transfer q independently.Much of the information in a(q,ro) can only be extracted if the reaction mechanism of the scattering process is understood. Both nuclear properties and the reaction mechanism can be studied in detail if the inclusive cross section can be shown to scale, 2 i.e., depend on a single variable y (q, ro) rather than on ro and q separately. The scaling property yields information on the reaction mechanism, and in the limit q-oo the scaling function provides a direct measurement of the longitudinal-momentum distribution of the nucleon constituents.Since the prediction of the scaling behavior by West 2 and the demonstration of this behavior in light nuclei, 3 • 4 there has been considerable discussion of the properties of y scaling. This interest has been motivated by the importance of extracting nuclear momentum distributions from the experimental data and by the potential of this scaling law to tell us how the system we study at finite q differs (by the nature of the scale breaking) from the ideal one defined by the lA. Discussions have appeared in the literature on this convergence, 5 on different scaling variables, and on the importance of final-state interactions (FSI) in the determination of the momentum distributions. 6 For 3 He y scaling has been used 7 • 8 to set limits on the modification of the free-nucleon properties by the nuclear medium.Experimental data suitable for such an interpretation and the study of scaling previously have been limited to A .$ 3. Detailed analysis has been performed for 3 He only, the case where the occurrence of y scaling was first demonstrated. 3 In this Letter we present data for a range of A from 4 to 197. These data, taken at very large momentum transfer and comparatively small energy transfer, complement the more extensive data on deep-inelastic scattering at large ro, for which the value of the Bjorken variable x =Q 2 /2mro is less than 1.Scaling is a concept valid only in the limit of very large momentum transfer; the scale-breaking quantities are the nuclear binding energies and nucleon momenta. With the present experiment we cover a large enough r...

Precise data on the neutron magnetic form factor G mn have been obtained with measurements of the ratio of cross sections of D(e, e ′ n) and D(e, e ′ p) up to momentum transfers of Q 2 = 0.9 (GeV/c) 2 . Data with typical uncertainties of 1.5% are presented. These data allow for the first time to extract a precise value of the magnetic radius of the neutron.

No abstract

No abstract

No abstract