Ratios ofN15/C12and

P. Bosted¹,

R. Fersch²,

G. S. Adams³

et al.

Abstract

The (W, Q 2 ) dependence of the ratio of inclusive electron scattering cross sections for 15 N/ 12 C was determined in the kinematic ranges 0.8 < W < 2 GeV and 0.2 < Q 2 < 1 GeV 2 using 2.285 GeV electrons and the CLAS detector at Jefferson Lab. The ratios exhibit only slight resonance structure, in agreement with a simple phenomenological model and an extrapolation of deep-inelastic scattering ratios to low Q 2 . Ratios of 4 He/ 12 C using 1.6 to 2.5 GeV electrons were measured with very high statistical precision and were used to correct for He in the N and C targets. The (W, Q 2 ) dependence of the 4 He/ 12 C ratios is in good agreement with that of the phenomenological model and exhibit significant resonance structure centered at W = 0.94, 1.23, and 1.5 GeV.

Measurement of Inclusive Proton Double-Spin Asymmetries and Polarized Structure Functions

“…It was indicated that the minicup had not overflowed, so L = 1.80 cm was used in the analysis. 12 The possibility of H 2 O contamination was also investigated by a careful inspection of the elastic peak region of the count ratio [95]. No tangible evidence of an elastic peak resulting from free hydrogen was found, so we concluded that water vapor contamination was not an issue.…”

“…Specifically, a polynomial fit to the superscaling function of Ref. [94] was used, with binding energies per nucleon E s ranging from 15-20 MeV, and the effective Fermi width parameter K F used in Fermi smearing ranging from 180-260 MeV, depending on the nucleon species [95]. This function was fit to both longitudinal and transverse cross-sections in the quasi-elastic region, with values for the G E and G M form factors parametrized in Ref.…”

“…The fit equation employed a total of 15 free parameters F i and 15 Fermismearing parameters η i in the form [95] …”

“…[95]. Cross-sections for the free proton and deuteron (neutron) were calculated from a fit to the world data of F The last factor that needs to be employed in any A-dependent nuclear scattering model is the well-known nuclear EMC effect [97], which is, in effect, a deviation from the linear scaling of inelastic scattering cross-section magnitude as a function of A.…”

“…Two separate target inserts were used in EG1b (Section 2.4), one containing the main (NH 3 and it was determined that the rate difference corresponded to no more than a 2% error in the overall effective carbon target length, so the runs were kept, accounting for this systematic error [95].…”