Ion-extraction polarimetry for tensor polarized deuterium internal targets

An ion-extraction polarimeter has been developed for internal target experiments in storage rings. Here, we report on the application of such a device for a tensor polarized deuterium gas target internal to a medium-energy electron storage ring. Ions, produced by the stored electron beam, were extracted from a storage cell using electrostatic lenses and a spherical deflector, transported to a mass-analyzer, and subsequently to a 3H(d,n)α tensor polarization analyzer. The method allows determining the density-averaged nuclear polarization of the target gas, independent of spatial and temporal variations. We discuss in detail the systematic uncertainties (< 5%) associated with this technique.