Measurement of inclusive spin structure functions of the deuteron

Abstract

We report the results of a new measurement of spin structure functions of the deuteron in the region of moderate momentum transfer $[{Q}^{2}=0.27--1.3(\mathrm{GeV}{/c)}^{2}]$ and final hadronic state mass in the nucleon resonance region $(W=1.08--2.0\mathrm{GeV}).$ We scattered a 2.5 GeV polarized continuous electron beam at Jefferson Lab off a dynamically polarized cryogenic solid state target ${(}^{15}{\mathrm{ND}}_{3})$ and detected the scattered electrons with the CEBAF large acceptance spectrometer. From our data, we extract the longitudinal double spin asymmetry ${A}_{||}$ and the spin structure function ${g}_{1}^{d}.$ Our data are generally in reasonable agreement with existing data from SLAC where they overlap, and they represent a substantial improvement in statistical precision. We compare our results with expectations for resonance asymmetries and extrapolated deep inelastic scaling results. Finally, we evaluate the first moment of the structure function ${g}_{1}^{d}$ and study its approach to both the deep inelastic limit at large ${Q}^{2}$ and to the Gerasimov-Drell-Hearn sum rule at the real photon limit ${(Q}^{2}\ensuremath{\rightarrow}0).$ We find that the first moment varies rapidly in the ${Q}^{2}$ range of our experiment and crosses zero at ${Q}^{2}$ between 0.5 and $0.8(\mathrm{GeV}{/c)}^{2},$ indicating the importance of the $\ensuremath{\Delta}$ resonance at these momentum transfers.