Document Type


Publication Date




Publication Title

Physics Letters B




134875 (1-5)


Due to the lack of free neutron targets, studies of the structure of the neutron are typically made by scattering electrons from either ²H or ³He targets. In order to extract useful neutron information from a ³He target, one must understand how the neutron in a ³He system differs from a free neutron by taking into account nuclear effects such as final state interactions and meson exchange currents. The target single spin asymmetry A⁰ʸ is an ideal probe of such effects, as any deviation from zero indicates effects beyond plane wave impulse approximation. New measurements of the target single spin asymmetry A⁰ʸ at Q² of 0.46 and 0.96 GeV/c² were made at Jefferson Lab using the quasi-elastic ³He↑(e,e'n) reaction. Our measured asymmetry decreases rapidly, from 20% at Q²=0.46 GeV/c² to nearly zero at Q²=0.96 GeV/c², demonstrating the fall-off of the reaction mechanism effects as Q² increases. We also observed a small epsiv-dependent increase in A⁰ʸ compared to previous measurements, particularly at moderate Q². This indicates that upcoming high Q² measurements from the Jefferson Lab 12 GeV program can cleanly probe neutron structure from polarized ³He using plane wave impulse approximation.

Original Publication Citation

Long, E., Zhang, Y. W., Mihovilovic, M., Jin, G., Sulkosky, V., Kelleher, A., . . . Zhu, L. (2019). Measurement of the single-spin asymmetry A⁰ʸ in quasi-elastic ³He↑(e,e'n) scattering at < Q2 < 1.0 GeV/c2. Physics Letters B, 797, 134875. doi:10.1016/j.physletb.2019.134875