Neutron News from Jefferson Lab

Understanding the spin structure of the nucleon in terms of quarks and gluons has been a challenging endeavor for more than 25 years. The quark's contribution to the spin of the nucleon is well established and amounts to about 30% of 1/2(h-bar). The study of gluon contributions and orbital angular momenta has been the main experimental (and theoretical) focus in recent years. New results of single-spin asymmetries in semi-inclusive deep-inelastic scattering will be presented. The Sivers- and Collins-Effects were investigated using asymmetries in pion electro-production off transversely polarized helium-3 targets.